Merge branch 'store_interface' of scossu/lsup_rdf into master

.gitignore

@@ -57,6 +57,9 @@ dkms.conf
 # Compiled binary files
 bin/*
 
+# Compiled documentation
+docs/html/
+
 # Valgrind data
 vgcore.*
 callgrind.out.*
@@ -102,7 +105,6 @@ venv.bak/
 
 ## LOCAL ##
 
-mdb_store/
 sandbox.c
 sandbox/
 

Doxyfile

@@ -0,0 +1,2665 @@
+# Doxyfile 1.9.3
+
+# This file describes the settings to be used by the documentation system
+# doxygen (www.doxygen.org) for a project.
+#
+# All text after a double hash (##) is considered a comment and is placed in
+# front of the TAG it is preceding.
+#
+# All text after a single hash (#) is considered a comment and will be ignored.
+# The format is:
+# TAG = value [value, ...]
+# For lists, items can also be appended using:
+# TAG += value [value, ...]
+# Values that contain spaces should be placed between quotes (\" \").
+
+#---------------------------------------------------------------------------
+# Project related configuration options
+#---------------------------------------------------------------------------
+
+# This tag specifies the encoding used for all characters in the configuration
+# file that follow. The default is UTF-8 which is also the encoding used for all
+# text before the first occurrence of this tag. Doxygen uses libiconv (or the
+# iconv built into libc) for the transcoding. See
+# https://www.gnu.org/software/libiconv/ for the list of possible encodings.
+# The default value is: UTF-8.
+
+DOXYFILE_ENCODING      = UTF-8
+
+# The PROJECT_NAME tag is a single word (or a sequence of words surrounded by
+# double-quotes, unless you are using Doxywizard) that should identify the
+# project for which the documentation is generated. This name is used in the
+# title of most generated pages and in a few other places.
+# The default value is: My Project.
+
+PROJECT_NAME           = LSUP_RDF
+
+# The PROJECT_NUMBER tag can be used to enter a project or revision number. This
+# could be handy for archiving the generated documentation or if some version
+# control system is used.
+
+PROJECT_NUMBER         = 1.0a2
+
+# Using the PROJECT_BRIEF tag one can provide an optional one line description
+# for a project that appears at the top of each page and should give viewer a
+# quick idea about the purpose of the project. Keep the description short.
+
+PROJECT_BRIEF          = "RDF library"
+
+# With the PROJECT_LOGO tag one can specify a logo or an icon that is included
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+# pixels and the maximum width should not exceed 200 pixels. Doxygen will copy
+# the logo to the output directory.
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+PROJECT_LOGO           =
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+# into which the generated documentation will be written. If a relative path is
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+
+OUTPUT_DIRECTORY       = docs
+
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+# option can be useful when feeding doxygen a huge amount of source files, where
+# putting all generated files in the same directory would otherwise causes
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+CREATE_SUBDIRS         = NO
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+ALLOW_UNICODE_NAMES    = YES
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+OUTPUT_LANGUAGE        = English
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+# documentation (similar to Javadoc). Set to NO to disable this.
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+BRIEF_MEMBER_DESC      = YES
+
+# If the REPEAT_BRIEF tag is set to YES, doxygen will prepend the brief
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+ALWAYS_DETAILED_SEC    = NO
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+# inherited members of a class in the documentation of that class as if those
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+
+INLINE_INHERITED_MEMB  = NO
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+FULL_PATH_NAMES        = YES
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+# YES.
+# The default value is: system dependent.
+
+CASE_SENSE_NAMES       = YES
+
+# If the HIDE_SCOPE_NAMES tag is set to NO then doxygen will show members with
+# their full class and namespace scopes in the documentation. If set to YES, the
+# scope will be hidden.
+# The default value is: NO.
+
+HIDE_SCOPE_NAMES       = YES
+
+# If the HIDE_COMPOUND_REFERENCE tag is set to NO (default) then doxygen will
+# append additional text to a page's title, such as Class Reference. If set to
+# YES the compound reference will be hidden.
+# The default value is: NO.
+
+HIDE_COMPOUND_REFERENCE= NO
+
+# If the SHOW_HEADERFILE tag is set to YES then the documentation for a class
+# will show which file needs to be included to use the class.
+# The default value is: YES.
+
+SHOW_HEADERFILE        = YES
+
+# If the SHOW_INCLUDE_FILES tag is set to YES then doxygen will put a list of
+# the files that are included by a file in the documentation of that file.
+# The default value is: YES.
+
+SHOW_INCLUDE_FILES     = YES
+
+# If the SHOW_GROUPED_MEMB_INC tag is set to YES then Doxygen will add for each
+# grouped member an include statement to the documentation, telling the reader
+# which file to include in order to use the member.
+# The default value is: NO.
+
+SHOW_GROUPED_MEMB_INC  = NO
+
+# If the FORCE_LOCAL_INCLUDES tag is set to YES then doxygen will list include
+# files with double quotes in the documentation rather than with sharp brackets.
+# The default value is: NO.
+
+FORCE_LOCAL_INCLUDES   = NO
+
+# If the INLINE_INFO tag is set to YES then a tag [inline] is inserted in the
+# documentation for inline members.
+# The default value is: YES.
+
+INLINE_INFO            = YES
+
+# If the SORT_MEMBER_DOCS tag is set to YES then doxygen will sort the
+# (detailed) documentation of file and class members alphabetically by member
+# name. If set to NO, the members will appear in declaration order.
+# The default value is: YES.
+
+SORT_MEMBER_DOCS       = YES
+
+# If the SORT_BRIEF_DOCS tag is set to YES then doxygen will sort the brief
+# descriptions of file, namespace and class members alphabetically by member
+# name. If set to NO, the members will appear in declaration order. Note that
+# this will also influence the order of the classes in the class list.
+# The default value is: NO.
+
+SORT_BRIEF_DOCS        = NO
+
+# If the SORT_MEMBERS_CTORS_1ST tag is set to YES then doxygen will sort the
+# (brief and detailed) documentation of class members so that constructors and
+# destructors are listed first. If set to NO the constructors will appear in the
+# respective orders defined by SORT_BRIEF_DOCS and SORT_MEMBER_DOCS.
+# Note: If SORT_BRIEF_DOCS is set to NO this option is ignored for sorting brief
+# member documentation.
+# Note: If SORT_MEMBER_DOCS is set to NO this option is ignored for sorting
+# detailed member documentation.
+# The default value is: NO.
+
+SORT_MEMBERS_CTORS_1ST = NO
+
+# If the SORT_GROUP_NAMES tag is set to YES then doxygen will sort the hierarchy
+# of group names into alphabetical order. If set to NO the group names will
+# appear in their defined order.
+# The default value is: NO.
+
+SORT_GROUP_NAMES       = NO
+
+# If the SORT_BY_SCOPE_NAME tag is set to YES, the class list will be sorted by
+# fully-qualified names, including namespaces. If set to NO, the class list will
+# be sorted only by class name, not including the namespace part.
+# Note: This option is not very useful if HIDE_SCOPE_NAMES is set to YES.
+# Note: This option applies only to the class list, not to the alphabetical
+# list.
+# The default value is: NO.
+
+SORT_BY_SCOPE_NAME     = NO
+
+# If the STRICT_PROTO_MATCHING option is enabled and doxygen fails to do proper
+# type resolution of all parameters of a function it will reject a match between
+# the prototype and the implementation of a member function even if there is
+# only one candidate or it is obvious which candidate to choose by doing a
+# simple string match. By disabling STRICT_PROTO_MATCHING doxygen will still
+# accept a match between prototype and implementation in such cases.
+# The default value is: NO.
+
+STRICT_PROTO_MATCHING  = NO
+
+# The GENERATE_TODOLIST tag can be used to enable (YES) or disable (NO) the todo
+# list. This list is created by putting \todo commands in the documentation.
+# The default value is: YES.
+
+GENERATE_TODOLIST      = YES
+
+# The GENERATE_TESTLIST tag can be used to enable (YES) or disable (NO) the test
+# list. This list is created by putting \test commands in the documentation.
+# The default value is: YES.
+
+GENERATE_TESTLIST      = YES
+
+# The GENERATE_BUGLIST tag can be used to enable (YES) or disable (NO) the bug
+# list. This list is created by putting \bug commands in the documentation.
+# The default value is: YES.
+
+GENERATE_BUGLIST       = YES
+
+# The GENERATE_DEPRECATEDLIST tag can be used to enable (YES) or disable (NO)
+# the deprecated list. This list is created by putting \deprecated commands in
+# the documentation.
+# The default value is: YES.
+
+GENERATE_DEPRECATEDLIST= YES
+
+# The ENABLED_SECTIONS tag can be used to enable conditional documentation
+# sections, marked by \if <section_label> ... \endif and \cond <section_label>
+# ... \endcond blocks.
+
+ENABLED_SECTIONS       =
+
+# The MAX_INITIALIZER_LINES tag determines the maximum number of lines that the
+# initial value of a variable or macro / define can have for it to appear in the
+# documentation. If the initializer consists of more lines than specified here
+# it will be hidden. Use a value of 0 to hide initializers completely. The
+# appearance of the value of individual variables and macros / defines can be
+# controlled using \showinitializer or \hideinitializer command in the
+# documentation regardless of this setting.
+# Minimum value: 0, maximum value: 10000, default value: 30.
+
+MAX_INITIALIZER_LINES  = 30
+
+# Set the SHOW_USED_FILES tag to NO to disable the list of files generated at
+# the bottom of the documentation of classes and structs. If set to YES, the
+# list will mention the files that were used to generate the documentation.
+# The default value is: YES.
+
+SHOW_USED_FILES        = YES
+
+# Set the SHOW_FILES tag to NO to disable the generation of the Files page. This
+# will remove the Files entry from the Quick Index and from the Folder Tree View
+# (if specified).
+# The default value is: YES.
+
+SHOW_FILES             = YES
+
+# Set the SHOW_NAMESPACES tag to NO to disable the generation of the Namespaces
+# page. This will remove the Namespaces entry from the Quick Index and from the
+# Folder Tree View (if specified).
+# The default value is: YES.
+
+SHOW_NAMESPACES        = YES
+
+# The FILE_VERSION_FILTER tag can be used to specify a program or script that
+# doxygen should invoke to get the current version for each file (typically from
+# the version control system). Doxygen will invoke the program by executing (via
+# popen()) the command command input-file, where command is the value of the
+# FILE_VERSION_FILTER tag, and input-file is the name of an input file provided
+# by doxygen. Whatever the program writes to standard output is used as the file
+# version. For an example see the documentation.
+
+FILE_VERSION_FILTER    =
+
+# The LAYOUT_FILE tag can be used to specify a layout file which will be parsed
+# by doxygen. The layout file controls the global structure of the generated
+# output files in an output format independent way. To create the layout file
+# that represents doxygen's defaults, run doxygen with the -l option. You can
+# optionally specify a file name after the option, if omitted DoxygenLayout.xml
+# will be used as the name of the layout file. See also section "Changing the
+# layout of pages" for information.
+#
+# Note that if you run doxygen from a directory containing a file called
+# DoxygenLayout.xml, doxygen will parse it automatically even if the LAYOUT_FILE
+# tag is left empty.
+
+LAYOUT_FILE            =
+
+# The CITE_BIB_FILES tag can be used to specify one or more bib files containing
+# the reference definitions. This must be a list of .bib files. The .bib
+# extension is automatically appended if omitted. This requires the bibtex tool
+# to be installed. See also https://en.wikipedia.org/wiki/BibTeX for more info.
+# For LaTeX the style of the bibliography can be controlled using
+# LATEX_BIB_STYLE. To use this feature you need bibtex and perl available in the
+# search path. See also \cite for info how to create references.
+
+CITE_BIB_FILES         =
+
+#---------------------------------------------------------------------------
+# Configuration options related to warning and progress messages
+#---------------------------------------------------------------------------
+
+# The QUIET tag can be used to turn on/off the messages that are generated to
+# standard output by doxygen. If QUIET is set to YES this implies that the
+# messages are off.
+# The default value is: NO.
+
+QUIET                  = NO
+
+# The WARNINGS tag can be used to turn on/off the warning messages that are
+# generated to standard error (stderr) by doxygen. If WARNINGS is set to YES
+# this implies that the warnings are on.
+#
+# Tip: Turn warnings on while writing the documentation.
+# The default value is: YES.
+
+WARNINGS               = YES
+
+# If the WARN_IF_UNDOCUMENTED tag is set to YES then doxygen will generate
+# warnings for undocumented members. If EXTRACT_ALL is set to YES then this flag
+# will automatically be disabled.
+# The default value is: YES.
+
+WARN_IF_UNDOCUMENTED   = YES
+
+# If the WARN_IF_DOC_ERROR tag is set to YES, doxygen will generate warnings for
+# potential errors in the documentation, such as documenting some parameters in
+# a documented function twice, or documenting parameters that don't exist or
+# using markup commands wrongly.
+# The default value is: YES.
+
+WARN_IF_DOC_ERROR      = YES
+
+# If WARN_IF_INCOMPLETE_DOC is set to YES, doxygen will warn about incomplete
+# function parameter documentation. If set to NO, doxygen will accept that some
+# parameters have no documentation without warning.
+# The default value is: YES.
+
+WARN_IF_INCOMPLETE_DOC = YES
+
+# This WARN_NO_PARAMDOC option can be enabled to get warnings for functions that
+# are documented, but have no documentation for their parameters or return
+# value. If set to NO, doxygen will only warn about wrong parameter
+# documentation, but not about the absence of documentation. If EXTRACT_ALL is
+# set to YES then this flag will automatically be disabled. See also
+# WARN_IF_INCOMPLETE_DOC
+# The default value is: NO.
+
+WARN_NO_PARAMDOC       = NO
+
+# If the WARN_AS_ERROR tag is set to YES then doxygen will immediately stop when
+# a warning is encountered. If the WARN_AS_ERROR tag is set to FAIL_ON_WARNINGS
+# then doxygen will continue running as if WARN_AS_ERROR tag is set to NO, but
+# at the end of the doxygen process doxygen will return with a non-zero status.
+# Possible values are: NO, YES and FAIL_ON_WARNINGS.
+# The default value is: NO.
+
+WARN_AS_ERROR          = NO
+
+# The WARN_FORMAT tag determines the format of the warning messages that doxygen
+# can produce. The string should contain the $file, $line, and $text tags, which
+# will be replaced by the file and line number from which the warning originated
+# and the warning text. Optionally the format may contain $version, which will
+# be replaced by the version of the file (if it could be obtained via
+# FILE_VERSION_FILTER)
+# The default value is: $file:$line: $text.
+
+WARN_FORMAT            = "$file:$line: $text"
+
+# The WARN_LOGFILE tag can be used to specify a file to which warning and error
+# messages should be written. If left blank the output is written to standard
+# error (stderr). In case the file specified cannot be opened for writing the
+# warning and error messages are written to standard error. When as file - is
+# specified the warning and error messages are written to standard output
+# (stdout).
+
+WARN_LOGFILE           =
+
+#---------------------------------------------------------------------------
+# Configuration options related to the input files
+#---------------------------------------------------------------------------
+
+# The INPUT tag is used to specify the files and/or directories that contain
+# documented source files. You may enter file names like myfile.cpp or
+# directories like /usr/src/myproject. Separate the files or directories with
+# spaces. See also FILE_PATTERNS and EXTENSION_MAPPING
+# Note: If this tag is empty the current directory is searched.
+
+INPUT                  = cpython \
+                         src \
+                         include
+
+# This tag can be used to specify the character encoding of the source files
+# that doxygen parses. Internally doxygen uses the UTF-8 encoding. Doxygen uses
+# libiconv (or the iconv built into libc) for the transcoding. See the libiconv
+# documentation (see:
+# https://www.gnu.org/software/libiconv/) for the list of possible encodings.
+# The default value is: UTF-8.
+
+INPUT_ENCODING         = UTF-8
+
+# If the value of the INPUT tag contains directories, you can use the
+# FILE_PATTERNS tag to specify one or more wildcard patterns (like *.cpp and
+# *.h) to filter out the source-files in the directories.
+#
+# Note that for custom extensions or not directly supported extensions you also
+# need to set EXTENSION_MAPPING for the extension otherwise the files are not
+# read by doxygen.
+#
+# Note the list of default checked file patterns might differ from the list of
+# default file extension mappings.
+#
+# If left blank the following patterns are tested:*.c, *.cc, *.cxx, *.cpp,
+# *.c++, *.java, *.ii, *.ixx, *.ipp, *.i++, *.inl, *.idl, *.ddl, *.odl, *.h,
+# *.hh, *.hxx, *.hpp, *.h++, *.l, *.cs, *.d, *.php, *.php4, *.php5, *.phtml,
+# *.inc, *.m, *.markdown, *.md, *.mm, *.dox (to be provided as doxygen C
+# comment), *.py, *.pyw, *.f90, *.f95, *.f03, *.f08, *.f18, *.f, *.for, *.vhd,
+# *.vhdl, *.ucf, *.qsf and *.ice.
+
+FILE_PATTERNS          = *.c \
+                         *.cc \
+                         *.cxx \
+                         *.cpp \
+                         *.c++ \
+                         *.h \
+                         *.hh \
+                         *.hxx \
+                         *.hpp \
+                         *.h++ \
+                         *.m \
+                         *.markdown \
+                         *.md \
+                         *.py \
+
+#                         *.java \
+#                         *.ii \
+#                         *.ixx \
+#                         *.ipp \
+#                         *.i++ \
+#                         *.inl \
+#                         *.idl \
+#                         *.ddl \
+#                         *.odl \
+#                         *.l \
+#                         *.cs \
+#                         *.d \
+#                         *.php \
+#                         *.php4 \
+#                         *.php5 \
+#                         *.phtml \
+#                         *.inc \
+#                         *.mm \
+#                         *.dox \
+#                         *.pyw \
+#                         *.f90 \
+#                         *.f95 \
+#                         *.f03 \
+#                         *.f08 \
+#                         *.f18 \
+#                         *.f \
+#                         *.for \
+#                         *.vhd \
+#                         *.vhdl \
+#                         *.ucf \
+#                         *.qsf \
+#                         *.ice
+
+# The RECURSIVE tag can be used to specify whether or not subdirectories should
+# be searched for input files as well.
+# The default value is: NO.
+
+RECURSIVE              = YES
+
+# The EXCLUDE tag can be used to specify files and/or directories that should be
+# excluded from the INPUT source files. This way you can easily exclude a
+# subdirectory from a directory tree whose root is specified with the INPUT tag.
+#
+# Note that relative paths are relative to the directory from which doxygen is
+# run.
+
+EXCLUDE                =
+
+# The EXCLUDE_SYMLINKS tag can be used to select whether or not files or
+# directories that are symbolic links (a Unix file system feature) are excluded
+# from the input.
+# The default value is: NO.
+
+EXCLUDE_SYMLINKS       = NO
+
+# If the value of the INPUT tag contains directories, you can use the
+# EXCLUDE_PATTERNS tag to specify one or more wildcard patterns to exclude
+# certain files from those directories.
+#
+# Note that the wildcards are matched against the file with absolute path, so to
+# exclude all test directories for example use the pattern */test/*
+
+EXCLUDE_PATTERNS       = *_dbg.*
+
+# The EXCLUDE_SYMBOLS tag can be used to specify one or more symbol names
+# (namespaces, classes, functions, etc.) that should be excluded from the
+# output. The symbol name can be a fully qualified name, a word, or if the
+# wildcard * is used, a substring. Examples: ANamespace, AClass,
+# ANamespace::AClass, ANamespace::*Test
+#
+# Note that the wildcards are matched against the file with absolute path, so to
+# exclude all test directories use the pattern */test/*
+
+EXCLUDE_SYMBOLS        =
+
+# The EXAMPLE_PATH tag can be used to specify one or more files or directories
+# that contain example code fragments that are included (see the \include
+# command).
+
+EXAMPLE_PATH           =
+
+# If the value of the EXAMPLE_PATH tag contains directories, you can use the
+# EXAMPLE_PATTERNS tag to specify one or more wildcard pattern (like *.cpp and
+# *.h) to filter out the source-files in the directories. If left blank all
+# files are included.
+
+EXAMPLE_PATTERNS       = *
+
+# If the EXAMPLE_RECURSIVE tag is set to YES then subdirectories will be
+# searched for input files to be used with the \include or \dontinclude commands
+# irrespective of the value of the RECURSIVE tag.
+# The default value is: NO.
+
+EXAMPLE_RECURSIVE      = NO
+
+# The IMAGE_PATH tag can be used to specify one or more files or directories
+# that contain images that are to be included in the documentation (see the
+# \image command).
+
+IMAGE_PATH             =
+
+# The INPUT_FILTER tag can be used to specify a program that doxygen should
+# invoke to filter for each input file. Doxygen will invoke the filter program
+# by executing (via popen()) the command:
+#
+# <filter> <input-file>
+#
+# where <filter> is the value of the INPUT_FILTER tag, and <input-file> is the
+# name of an input file. Doxygen will then use the output that the filter
+# program writes to standard output. If FILTER_PATTERNS is specified, this tag
+# will be ignored.
+#
+# Note that the filter must not add or remove lines; it is applied before the
+# code is scanned, but not when the output code is generated. If lines are added
+# or removed, the anchors will not be placed correctly.
+#
+# Note that for custom extensions or not directly supported extensions you also
+# need to set EXTENSION_MAPPING for the extension otherwise the files are not
+# properly processed by doxygen.
+
+INPUT_FILTER           =
+
+# The FILTER_PATTERNS tag can be used to specify filters on a per file pattern
+# basis. Doxygen will compare the file name with each pattern and apply the
+# filter if there is a match. The filters are a list of the form: pattern=filter
+# (like *.cpp=my_cpp_filter). See INPUT_FILTER for further information on how
+# filters are used. If the FILTER_PATTERNS tag is empty or if none of the
+# patterns match the file name, INPUT_FILTER is applied.
+#
+# Note that for custom extensions or not directly supported extensions you also
+# need to set EXTENSION_MAPPING for the extension otherwise the files are not
+# properly processed by doxygen.
+
+FILTER_PATTERNS        =
+
+# If the FILTER_SOURCE_FILES tag is set to YES, the input filter (if set using
+# INPUT_FILTER) will also be used to filter the input files that are used for
+# producing the source files to browse (i.e. when SOURCE_BROWSER is set to YES).
+# The default value is: NO.
+
+FILTER_SOURCE_FILES    = NO
+
+# The FILTER_SOURCE_PATTERNS tag can be used to specify source filters per file
+# pattern. A pattern will override the setting for FILTER_PATTERN (if any) and
+# it is also possible to disable source filtering for a specific pattern using
+# *.ext= (so without naming a filter).
+# This tag requires that the tag FILTER_SOURCE_FILES is set to YES.
+
+FILTER_SOURCE_PATTERNS =
+
+# If the USE_MDFILE_AS_MAINPAGE tag refers to the name of a markdown file that
+# is part of the input, its contents will be placed on the main page
+# (index.html). This can be useful if you have a project on for instance GitHub
+# and want to reuse the introduction page also for the doxygen output.
+
+USE_MDFILE_AS_MAINPAGE =
+
+#---------------------------------------------------------------------------
+# Configuration options related to source browsing
+#---------------------------------------------------------------------------
+
+# If the SOURCE_BROWSER tag is set to YES then a list of source files will be
+# generated. Documented entities will be cross-referenced with these sources.
+#
+# Note: To get rid of all source code in the generated output, make sure that
+# also VERBATIM_HEADERS is set to NO.
+# The default value is: NO.
+
+SOURCE_BROWSER         = YES
+
+# Setting the INLINE_SOURCES tag to YES will include the body of functions,
+# classes and enums directly into the documentation.
+# The default value is: NO.
+
+INLINE_SOURCES         = NO
+
+# Setting the STRIP_CODE_COMMENTS tag to YES will instruct doxygen to hide any
+# special comment blocks from generated source code fragments. Normal C, C++ and
+# Fortran comments will always remain visible.
+# The default value is: YES.
+
+STRIP_CODE_COMMENTS    = YES
+
+# If the REFERENCED_BY_RELATION tag is set to YES then for each documented
+# entity all documented functions referencing it will be listed.
+# The default value is: NO.
+
+REFERENCED_BY_RELATION = NO
+
+# If the REFERENCES_RELATION tag is set to YES then for each documented function
+# all documented entities called/used by that function will be listed.
+# The default value is: NO.
+
+REFERENCES_RELATION    = NO
+
+# If the REFERENCES_LINK_SOURCE tag is set to YES and SOURCE_BROWSER tag is set
+# to YES then the hyperlinks from functions in REFERENCES_RELATION and
+# REFERENCED_BY_RELATION lists will link to the source code. Otherwise they will
+# link to the documentation.
+# The default value is: YES.
+
+REFERENCES_LINK_SOURCE = YES
+
+# If SOURCE_TOOLTIPS is enabled (the default) then hovering a hyperlink in the
+# source code will show a tooltip with additional information such as prototype,
+# brief description and links to the definition and documentation. Since this
+# will make the HTML file larger and loading of large files a bit slower, you
+# can opt to disable this feature.
+# The default value is: YES.
+# This tag requires that the tag SOURCE_BROWSER is set to YES.
+
+SOURCE_TOOLTIPS        = YES
+
+# If the USE_HTAGS tag is set to YES then the references to source code will
+# point to the HTML generated by the htags(1) tool instead of doxygen built-in
+# source browser. The htags tool is part of GNU's global source tagging system
+# (see https://www.gnu.org/software/global/global.html). You will need version
+# 4.8.6 or higher.
+#
+# To use it do the following:
+# - Install the latest version of global
+# - Enable SOURCE_BROWSER and USE_HTAGS in the configuration file
+# - Make sure the INPUT points to the root of the source tree
+# - Run doxygen as normal
+#
+# Doxygen will invoke htags (and that will in turn invoke gtags), so these
+# tools must be available from the command line (i.e. in the search path).
+#
+# The result: instead of the source browser generated by doxygen, the links to
+# source code will now point to the output of htags.
+# The default value is: NO.
+# This tag requires that the tag SOURCE_BROWSER is set to YES.
+
+USE_HTAGS              = NO
+
+# If the VERBATIM_HEADERS tag is set the YES then doxygen will generate a
+# verbatim copy of the header file for each class for which an include is
+# specified. Set to NO to disable this.
+# See also: Section \class.
+# The default value is: YES.
+
+VERBATIM_HEADERS       = YES
+
+#---------------------------------------------------------------------------
+# Configuration options related to the alphabetical class index
+#---------------------------------------------------------------------------
+
+# If the ALPHABETICAL_INDEX tag is set to YES, an alphabetical index of all
+# compounds will be generated. Enable this if the project contains a lot of
+# classes, structs, unions or interfaces.
+# The default value is: YES.
+
+ALPHABETICAL_INDEX     = NO
+
+# In case all classes in a project start with a common prefix, all classes will
+# be put under the same header in the alphabetical index. The IGNORE_PREFIX tag
+# can be used to specify a prefix (or a list of prefixes) that should be ignored
+# while generating the index headers.
+# This tag requires that the tag ALPHABETICAL_INDEX is set to YES.
+
+IGNORE_PREFIX          =
+
+#---------------------------------------------------------------------------
+# Configuration options related to the HTML output
+#---------------------------------------------------------------------------
+
+# If the GENERATE_HTML tag is set to YES, doxygen will generate HTML output
+# The default value is: YES.
+
+GENERATE_HTML          = YES
+
+# The HTML_OUTPUT tag is used to specify where the HTML docs will be put. If a
+# relative path is entered the value of OUTPUT_DIRECTORY will be put in front of
+# it.
+# The default directory is: html.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+HTML_OUTPUT            = html
+
+# The HTML_FILE_EXTENSION tag can be used to specify the file extension for each
+# generated HTML page (for example: .htm, .php, .asp).
+# The default value is: .html.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+HTML_FILE_EXTENSION    = .html
+
+# The HTML_HEADER tag can be used to specify a user-defined HTML header file for
+# each generated HTML page. If the tag is left blank doxygen will generate a
+# standard header.
+#
+# To get valid HTML the header file that includes any scripts and style sheets
+# that doxygen needs, which is dependent on the configuration options used (e.g.
+# the setting GENERATE_TREEVIEW). It is highly recommended to start with a
+# default header using
+# doxygen -w html new_header.html new_footer.html new_stylesheet.css
+# YourConfigFile
+# and then modify the file new_header.html. See also section "Doxygen usage"
+# for information on how to generate the default header that doxygen normally
+# uses.
+# Note: The header is subject to change so you typically have to regenerate the
+# default header when upgrading to a newer version of doxygen. For a description
+# of the possible markers and block names see the documentation.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+HTML_HEADER            =
+
+# The HTML_FOOTER tag can be used to specify a user-defined HTML footer for each
+# generated HTML page. If the tag is left blank doxygen will generate a standard
+# footer. See HTML_HEADER for more information on how to generate a default
+# footer and what special commands can be used inside the footer. See also
+# section "Doxygen usage" for information on how to generate the default footer
+# that doxygen normally uses.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+HTML_FOOTER            =
+
+# The HTML_STYLESHEET tag can be used to specify a user-defined cascading style
+# sheet that is used by each HTML page. It can be used to fine-tune the look of
+# the HTML output. If left blank doxygen will generate a default style sheet.
+# See also section "Doxygen usage" for information on how to generate the style
+# sheet that doxygen normally uses.
+# Note: It is recommended to use HTML_EXTRA_STYLESHEET instead of this tag, as
+# it is more robust and this tag (HTML_STYLESHEET) will in the future become
+# obsolete.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+HTML_STYLESHEET        =
+
+# The HTML_EXTRA_STYLESHEET tag can be used to specify additional user-defined
+# cascading style sheets that are included after the standard style sheets
+# created by doxygen. Using this option one can overrule certain style aspects.
+# This is preferred over using HTML_STYLESHEET since it does not replace the
+# standard style sheet and is therefore more robust against future updates.
+# Doxygen will copy the style sheet files to the output directory.
+# Note: The order of the extra style sheet files is of importance (e.g. the last
+# style sheet in the list overrules the setting of the previous ones in the
+# list). For an example see the documentation.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+HTML_EXTRA_STYLESHEET  =
+
+# The HTML_EXTRA_FILES tag can be used to specify one or more extra images or
+# other source files which should be copied to the HTML output directory. Note
+# that these files will be copied to the base HTML output directory. Use the
+# $relpath^ marker in the HTML_HEADER and/or HTML_FOOTER files to load these
+# files. In the HTML_STYLESHEET file, use the file name only. Also note that the
+# files will be copied as-is; there are no commands or markers available.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+HTML_EXTRA_FILES       =
+
+# The HTML_COLORSTYLE_HUE tag controls the color of the HTML output. Doxygen
+# will adjust the colors in the style sheet and background images according to
+# this color. Hue is specified as an angle on a color-wheel, see
+# https://en.wikipedia.org/wiki/Hue for more information. For instance the value
+# 0 represents red, 60 is yellow, 120 is green, 180 is cyan, 240 is blue, 300
+# purple, and 360 is red again.
+# Minimum value: 0, maximum value: 359, default value: 220.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+HTML_COLORSTYLE_HUE    = 220
+
+# The HTML_COLORSTYLE_SAT tag controls the purity (or saturation) of the colors
+# in the HTML output. For a value of 0 the output will use gray-scales only. A
+# value of 255 will produce the most vivid colors.
+# Minimum value: 0, maximum value: 255, default value: 100.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+HTML_COLORSTYLE_SAT    = 100
+
+# The HTML_COLORSTYLE_GAMMA tag controls the gamma correction applied to the
+# luminance component of the colors in the HTML output. Values below 100
+# gradually make the output lighter, whereas values above 100 make the output
+# darker. The value divided by 100 is the actual gamma applied, so 80 represents
+# a gamma of 0.8, The value 220 represents a gamma of 2.2, and 100 does not
+# change the gamma.
+# Minimum value: 40, maximum value: 240, default value: 80.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+HTML_COLORSTYLE_GAMMA  = 80
+
+# If the HTML_TIMESTAMP tag is set to YES then the footer of each generated HTML
+# page will contain the date and time when the page was generated. Setting this
+# to YES can help to show when doxygen was last run and thus if the
+# documentation is up to date.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+HTML_TIMESTAMP         = NO
+
+# If the HTML_DYNAMIC_MENUS tag is set to YES then the generated HTML
+# documentation will contain a main index with vertical navigation menus that
+# are dynamically created via JavaScript. If disabled, the navigation index will
+# consists of multiple levels of tabs that are statically embedded in every HTML
+# page. Disable this option to support browsers that do not have JavaScript,
+# like the Qt help browser.
+# The default value is: YES.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+HTML_DYNAMIC_MENUS     = YES
+
+# If the HTML_DYNAMIC_SECTIONS tag is set to YES then the generated HTML
+# documentation will contain sections that can be hidden and shown after the
+# page has loaded.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+HTML_DYNAMIC_SECTIONS  = NO
+
+# With HTML_INDEX_NUM_ENTRIES one can control the preferred number of entries
+# shown in the various tree structured indices initially; the user can expand
+# and collapse entries dynamically later on. Doxygen will expand the tree to
+# such a level that at most the specified number of entries are visible (unless
+# a fully collapsed tree already exceeds this amount). So setting the number of
+# entries 1 will produce a full collapsed tree by default. 0 is a special value
+# representing an infinite number of entries and will result in a full expanded
+# tree by default.
+# Minimum value: 0, maximum value: 9999, default value: 100.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+HTML_INDEX_NUM_ENTRIES = 100
+
+# If the GENERATE_DOCSET tag is set to YES, additional index files will be
+# generated that can be used as input for Apple's Xcode 3 integrated development
+# environment (see:
+# https://developer.apple.com/xcode/), introduced with OSX 10.5 (Leopard). To
+# create a documentation set, doxygen will generate a Makefile in the HTML
+# output directory. Running make will produce the docset in that directory and
+# running make install will install the docset in
+# ~/Library/Developer/Shared/Documentation/DocSets so that Xcode will find it at
+# startup. See https://developer.apple.com/library/archive/featuredarticles/Doxy
+# genXcode/_index.html for more information.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+GENERATE_DOCSET        = NO
+
+# This tag determines the name of the docset feed. A documentation feed provides
+# an umbrella under which multiple documentation sets from a single provider
+# (such as a company or product suite) can be grouped.
+# The default value is: Doxygen generated docs.
+# This tag requires that the tag GENERATE_DOCSET is set to YES.
+
+DOCSET_FEEDNAME        = "Doxygen generated docs"
+
+# This tag determines the URL of the docset feed. A documentation feed provides
+# an umbrella under which multiple documentation sets from a single provider
+# (such as a company or product suite) can be grouped.
+# This tag requires that the tag GENERATE_DOCSET is set to YES.
+
+DOCSET_FEEDURL         =
+
+# This tag specifies a string that should uniquely identify the documentation
+# set bundle. This should be a reverse domain-name style string, e.g.
+# com.mycompany.MyDocSet. Doxygen will append .docset to the name.
+# The default value is: org.doxygen.Project.
+# This tag requires that the tag GENERATE_DOCSET is set to YES.
+
+DOCSET_BUNDLE_ID       = org.doxygen.Project
+
+# The DOCSET_PUBLISHER_ID tag specifies a string that should uniquely identify
+# the documentation publisher. This should be a reverse domain-name style
+# string, e.g. com.mycompany.MyDocSet.documentation.
+# The default value is: org.doxygen.Publisher.
+# This tag requires that the tag GENERATE_DOCSET is set to YES.
+
+DOCSET_PUBLISHER_ID    = org.doxygen.Publisher
+
+# The DOCSET_PUBLISHER_NAME tag identifies the documentation publisher.
+# The default value is: Publisher.
+# This tag requires that the tag GENERATE_DOCSET is set to YES.
+
+DOCSET_PUBLISHER_NAME  = Publisher
+
+# If the GENERATE_HTMLHELP tag is set to YES then doxygen generates three
+# additional HTML index files: index.hhp, index.hhc, and index.hhk. The
+# index.hhp is a project file that can be read by Microsoft's HTML Help Workshop
+# on Windows. In the beginning of 2021 Microsoft took the original page, with
+# a.o. the download links, offline the HTML help workshop was already many years
+# in maintenance mode). You can download the HTML help workshop from the web
+# archives at Installation executable (see:
+# http://web.archive.org/web/20160201063255/http://download.microsoft.com/downlo
+# ad/0/A/9/0A939EF6-E31C-430F-A3DF-DFAE7960D564/htmlhelp.exe).
+#
+# The HTML Help Workshop contains a compiler that can convert all HTML output
+# generated by doxygen into a single compiled HTML file (.chm). Compiled HTML
+# files are now used as the Windows 98 help format, and will replace the old
+# Windows help format (.hlp) on all Windows platforms in the future. Compressed
+# HTML files also contain an index, a table of contents, and you can search for
+# words in the documentation. The HTML workshop also contains a viewer for
+# compressed HTML files.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+GENERATE_HTMLHELP      = NO
+
+# The CHM_FILE tag can be used to specify the file name of the resulting .chm
+# file. You can add a path in front of the file if the result should not be
+# written to the html output directory.
+# This tag requires that the tag GENERATE_HTMLHELP is set to YES.
+
+CHM_FILE               =
+
+# The HHC_LOCATION tag can be used to specify the location (absolute path
+# including file name) of the HTML help compiler (hhc.exe). If non-empty,
+# doxygen will try to run the HTML help compiler on the generated index.hhp.
+# The file has to be specified with full path.
+# This tag requires that the tag GENERATE_HTMLHELP is set to YES.
+
+HHC_LOCATION           =
+
+# The GENERATE_CHI flag controls if a separate .chi index file is generated
+# (YES) or that it should be included in the main .chm file (NO).
+# The default value is: NO.
+# This tag requires that the tag GENERATE_HTMLHELP is set to YES.
+
+GENERATE_CHI           = NO
+
+# The CHM_INDEX_ENCODING is used to encode HtmlHelp index (hhk), content (hhc)
+# and project file content.
+# This tag requires that the tag GENERATE_HTMLHELP is set to YES.
+
+CHM_INDEX_ENCODING     =
+
+# The BINARY_TOC flag controls whether a binary table of contents is generated
+# (YES) or a normal table of contents (NO) in the .chm file. Furthermore it
+# enables the Previous and Next buttons.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_HTMLHELP is set to YES.
+
+BINARY_TOC             = NO
+
+# The TOC_EXPAND flag can be set to YES to add extra items for group members to
+# the table of contents of the HTML help documentation and to the tree view.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_HTMLHELP is set to YES.
+
+TOC_EXPAND             = NO
+
+# If the GENERATE_QHP tag is set to YES and both QHP_NAMESPACE and
+# QHP_VIRTUAL_FOLDER are set, an additional index file will be generated that
+# can be used as input for Qt's qhelpgenerator to generate a Qt Compressed Help
+# (.qch) of the generated HTML documentation.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+GENERATE_QHP           = NO
+
+# If the QHG_LOCATION tag is specified, the QCH_FILE tag can be used to specify
+# the file name of the resulting .qch file. The path specified is relative to
+# the HTML output folder.
+# This tag requires that the tag GENERATE_QHP is set to YES.
+
+QCH_FILE               =
+
+# The QHP_NAMESPACE tag specifies the namespace to use when generating Qt Help
+# Project output. For more information please see Qt Help Project / Namespace
+# (see:
+# https://doc.qt.io/archives/qt-4.8/qthelpproject.html#namespace).
+# The default value is: org.doxygen.Project.
+# This tag requires that the tag GENERATE_QHP is set to YES.
+
+QHP_NAMESPACE          = org.doxygen.Project
+
+# The QHP_VIRTUAL_FOLDER tag specifies the namespace to use when generating Qt
+# Help Project output. For more information please see Qt Help Project / Virtual
+# Folders (see:
+# https://doc.qt.io/archives/qt-4.8/qthelpproject.html#virtual-folders).
+# The default value is: doc.
+# This tag requires that the tag GENERATE_QHP is set to YES.
+
+QHP_VIRTUAL_FOLDER     = doc
+
+# If the QHP_CUST_FILTER_NAME tag is set, it specifies the name of a custom
+# filter to add. For more information please see Qt Help Project / Custom
+# Filters (see:
+# https://doc.qt.io/archives/qt-4.8/qthelpproject.html#custom-filters).
+# This tag requires that the tag GENERATE_QHP is set to YES.
+
+QHP_CUST_FILTER_NAME   =
+
+# The QHP_CUST_FILTER_ATTRS tag specifies the list of the attributes of the
+# custom filter to add. For more information please see Qt Help Project / Custom
+# Filters (see:
+# https://doc.qt.io/archives/qt-4.8/qthelpproject.html#custom-filters).
+# This tag requires that the tag GENERATE_QHP is set to YES.
+
+QHP_CUST_FILTER_ATTRS  =
+
+# The QHP_SECT_FILTER_ATTRS tag specifies the list of the attributes this
+# project's filter section matches. Qt Help Project / Filter Attributes (see:
+# https://doc.qt.io/archives/qt-4.8/qthelpproject.html#filter-attributes).
+# This tag requires that the tag GENERATE_QHP is set to YES.
+
+QHP_SECT_FILTER_ATTRS  =
+
+# The QHG_LOCATION tag can be used to specify the location (absolute path
+# including file name) of Qt's qhelpgenerator. If non-empty doxygen will try to
+# run qhelpgenerator on the generated .qhp file.
+# This tag requires that the tag GENERATE_QHP is set to YES.
+
+QHG_LOCATION           =
+
+# If the GENERATE_ECLIPSEHELP tag is set to YES, additional index files will be
+# generated, together with the HTML files, they form an Eclipse help plugin. To
+# install this plugin and make it available under the help contents menu in
+# Eclipse, the contents of the directory containing the HTML and XML files needs
+# to be copied into the plugins directory of eclipse. The name of the directory
+# within the plugins directory should be the same as the ECLIPSE_DOC_ID value.
+# After copying Eclipse needs to be restarted before the help appears.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+GENERATE_ECLIPSEHELP   = NO
+
+# A unique identifier for the Eclipse help plugin. When installing the plugin
+# the directory name containing the HTML and XML files should also have this
+# name. Each documentation set should have its own identifier.
+# The default value is: org.doxygen.Project.
+# This tag requires that the tag GENERATE_ECLIPSEHELP is set to YES.
+
+ECLIPSE_DOC_ID         = org.doxygen.Project
+
+# If you want full control over the layout of the generated HTML pages it might
+# be necessary to disable the index and replace it with your own. The
+# DISABLE_INDEX tag can be used to turn on/off the condensed index (tabs) at top
+# of each HTML page. A value of NO enables the index and the value YES disables
+# it. Since the tabs in the index contain the same information as the navigation
+# tree, you can set this option to YES if you also set GENERATE_TREEVIEW to YES.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+DISABLE_INDEX          = YES
+
+# The GENERATE_TREEVIEW tag is used to specify whether a tree-like index
+# structure should be generated to display hierarchical information. If the tag
+# value is set to YES, a side panel will be generated containing a tree-like
+# index structure (just like the one that is generated for HTML Help). For this
+# to work a browser that supports JavaScript, DHTML, CSS and frames is required
+# (i.e. any modern browser). Windows users are probably better off using the
+# HTML help feature. Via custom style sheets (see HTML_EXTRA_STYLESHEET) one can
+# further fine tune the look of the index (see "Fine-tuning the output"). As an
+# example, the default style sheet generated by doxygen has an example that
+# shows how to put an image at the root of the tree instead of the PROJECT_NAME.
+# Since the tree basically has the same information as the tab index, you could
+# consider setting DISABLE_INDEX to YES when enabling this option.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+GENERATE_TREEVIEW      = YES
+
+# When both GENERATE_TREEVIEW and DISABLE_INDEX are set to YES, then the
+# FULL_SIDEBAR option determines if the side bar is limited to only the treeview
+# area (value NO) or if it should extend to the full height of the window (value
+# YES). Setting this to YES gives a layout similar to
+# https://docs.readthedocs.io with more room for contents, but less room for the
+# project logo, title, and description. If either GENERATE_TREEVIEW or
+# DISABLE_INDEX is set to NO, this option has no effect.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+FULL_SIDEBAR           = NO
+
+# The ENUM_VALUES_PER_LINE tag can be used to set the number of enum values that
+# doxygen will group on one line in the generated HTML documentation.
+#
+# Note that a value of 0 will completely suppress the enum values from appearing
+# in the overview section.
+# Minimum value: 0, maximum value: 20, default value: 4.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+ENUM_VALUES_PER_LINE   = 4
+
+# If the treeview is enabled (see GENERATE_TREEVIEW) then this tag can be used
+# to set the initial width (in pixels) of the frame in which the tree is shown.
+# Minimum value: 0, maximum value: 1500, default value: 250.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+TREEVIEW_WIDTH         = 250
+
+# If the EXT_LINKS_IN_WINDOW option is set to YES, doxygen will open links to
+# external symbols imported via tag files in a separate window.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+EXT_LINKS_IN_WINDOW    = NO
+
+# If the OBFUSCATE_EMAILS tag is set to YES, doxygen will obfuscate email
+# addresses.
+# The default value is: YES.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+OBFUSCATE_EMAILS       = YES
+
+# If the HTML_FORMULA_FORMAT option is set to svg, doxygen will use the pdf2svg
+# tool (see https://github.com/dawbarton/pdf2svg) or inkscape (see
+# https://inkscape.org) to generate formulas as SVG images instead of PNGs for
+# the HTML output. These images will generally look nicer at scaled resolutions.
+# Possible values are: png (the default) and svg (looks nicer but requires the
+# pdf2svg or inkscape tool).
+# The default value is: png.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+HTML_FORMULA_FORMAT    = png
+
+# Use this tag to change the font size of LaTeX formulas included as images in
+# the HTML documentation. When you change the font size after a successful
+# doxygen run you need to manually remove any form_*.png images from the HTML
+# output directory to force them to be regenerated.
+# Minimum value: 8, maximum value: 50, default value: 10.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+FORMULA_FONTSIZE       = 10
+
+# Use the FORMULA_TRANSPARENT tag to determine whether or not the images
+# generated for formulas are transparent PNGs. Transparent PNGs are not
+# supported properly for IE 6.0, but are supported on all modern browsers.
+#
+# Note that when changing this option you need to delete any form_*.png files in
+# the HTML output directory before the changes have effect.
+# The default value is: YES.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+FORMULA_TRANSPARENT    = YES
+
+# The FORMULA_MACROFILE can contain LaTeX \newcommand and \renewcommand commands
+# to create new LaTeX commands to be used in formulas as building blocks. See
+# the section "Including formulas" for details.
+
+FORMULA_MACROFILE      =
+
+# Enable the USE_MATHJAX option to render LaTeX formulas using MathJax (see
+# https://www.mathjax.org) which uses client side JavaScript for the rendering
+# instead of using pre-rendered bitmaps. Use this if you do not have LaTeX
+# installed or if you want to formulas look prettier in the HTML output. When
+# enabled you may also need to install MathJax separately and configure the path
+# to it using the MATHJAX_RELPATH option.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+USE_MATHJAX            = NO
+
+# With MATHJAX_VERSION it is possible to specify the MathJax version to be used.
+# Note that the different versions of MathJax have different requirements with
+# regards to the different settings, so it is possible that also other MathJax
+# settings have to be changed when switching between the different MathJax
+# versions.
+# Possible values are: MathJax_2 and MathJax_3.
+# The default value is: MathJax_2.
+# This tag requires that the tag USE_MATHJAX is set to YES.
+
+MATHJAX_VERSION        = MathJax_2
+
+# When MathJax is enabled you can set the default output format to be used for
+# the MathJax output. For more details about the output format see MathJax
+# version 2 (see:
+# http://docs.mathjax.org/en/v2.7-latest/output.html) and MathJax version 3
+# (see:
+# http://docs.mathjax.org/en/latest/web/components/output.html).
+# Possible values are: HTML-CSS (which is slower, but has the best
+# compatibility. This is the name for Mathjax version 2, for MathJax version 3
+# this will be translated into chtml), NativeMML (i.e. MathML. Only supported
+# for NathJax 2. For MathJax version 3 chtml will be used instead.), chtml (This
+# is the name for Mathjax version 3, for MathJax version 2 this will be
+# translated into HTML-CSS) and SVG.
+# The default value is: HTML-CSS.
+# This tag requires that the tag USE_MATHJAX is set to YES.
+
+MATHJAX_FORMAT         = HTML-CSS
+
+# When MathJax is enabled you need to specify the location relative to the HTML
+# output directory using the MATHJAX_RELPATH option. The destination directory
+# should contain the MathJax.js script. For instance, if the mathjax directory
+# is located at the same level as the HTML output directory, then
+# MATHJAX_RELPATH should be ../mathjax. The default value points to the MathJax
+# Content Delivery Network so you can quickly see the result without installing
+# MathJax. However, it is strongly recommended to install a local copy of
+# MathJax from https://www.mathjax.org before deployment. The default value is:
+# - in case of MathJax version 2: https://cdn.jsdelivr.net/npm/mathjax@2
+# - in case of MathJax version 3: https://cdn.jsdelivr.net/npm/mathjax@3
+# This tag requires that the tag USE_MATHJAX is set to YES.
+
+MATHJAX_RELPATH        =
+
+# The MATHJAX_EXTENSIONS tag can be used to specify one or more MathJax
+# extension names that should be enabled during MathJax rendering. For example
+# for MathJax version 2 (see
+# https://docs.mathjax.org/en/v2.7-latest/tex.html#tex-and-latex-extensions):
+# MATHJAX_EXTENSIONS = TeX/AMSmath TeX/AMSsymbols
+# For example for MathJax version 3 (see
+# http://docs.mathjax.org/en/latest/input/tex/extensions/index.html):
+# MATHJAX_EXTENSIONS = ams
+# This tag requires that the tag USE_MATHJAX is set to YES.
+
+MATHJAX_EXTENSIONS     =
+
+# The MATHJAX_CODEFILE tag can be used to specify a file with javascript pieces
+# of code that will be used on startup of the MathJax code. See the MathJax site
+# (see:
+# http://docs.mathjax.org/en/v2.7-latest/output.html) for more details. For an
+# example see the documentation.
+# This tag requires that the tag USE_MATHJAX is set to YES.
+
+MATHJAX_CODEFILE       =
+
+# When the SEARCHENGINE tag is enabled doxygen will generate a search box for
+# the HTML output. The underlying search engine uses javascript and DHTML and
+# should work on any modern browser. Note that when using HTML help
+# (GENERATE_HTMLHELP), Qt help (GENERATE_QHP), or docsets (GENERATE_DOCSET)
+# there is already a search function so this one should typically be disabled.
+# For large projects the javascript based search engine can be slow, then
+# enabling SERVER_BASED_SEARCH may provide a better solution. It is possible to
+# search using the keyboard; to jump to the search box use <access key> + S
+# (what the <access key> is depends on the OS and browser, but it is typically
+# <CTRL>, <ALT>/<option>, or both). Inside the search box use the <cursor down
+# key> to jump into the search results window, the results can be navigated
+# using the <cursor keys>. Press <Enter> to select an item or <escape> to cancel
+# the search. The filter options can be selected when the cursor is inside the
+# search box by pressing <Shift>+<cursor down>. Also here use the <cursor keys>
+# to select a filter and <Enter> or <escape> to activate or cancel the filter
+# option.
+# The default value is: YES.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+SEARCHENGINE           = YES
+
+# When the SERVER_BASED_SEARCH tag is enabled the search engine will be
+# implemented using a web server instead of a web client using JavaScript. There
+# are two flavors of web server based searching depending on the EXTERNAL_SEARCH
+# setting. When disabled, doxygen will generate a PHP script for searching and
+# an index file used by the script. When EXTERNAL_SEARCH is enabled the indexing
+# and searching needs to be provided by external tools. See the section
+# "External Indexing and Searching" for details.
+# The default value is: NO.
+# This tag requires that the tag SEARCHENGINE is set to YES.
+
+SERVER_BASED_SEARCH    = NO
+
+# When EXTERNAL_SEARCH tag is enabled doxygen will no longer generate the PHP
+# script for searching. Instead the search results are written to an XML file
+# which needs to be processed by an external indexer. Doxygen will invoke an
+# external search engine pointed to by the SEARCHENGINE_URL option to obtain the
+# search results.
+#
+# Doxygen ships with an example indexer (doxyindexer) and search engine
+# (doxysearch.cgi) which are based on the open source search engine library
+# Xapian (see:
+# https://xapian.org/).
+#
+# See the section "External Indexing and Searching" for details.
+# The default value is: NO.
+# This tag requires that the tag SEARCHENGINE is set to YES.
+
+EXTERNAL_SEARCH        = NO
+
+# The SEARCHENGINE_URL should point to a search engine hosted by a web server
+# which will return the search results when EXTERNAL_SEARCH is enabled.
+#
+# Doxygen ships with an example indexer (doxyindexer) and search engine
+# (doxysearch.cgi) which are based on the open source search engine library
+# Xapian (see:
+# https://xapian.org/). See the section "External Indexing and Searching" for
+# details.
+# This tag requires that the tag SEARCHENGINE is set to YES.
+
+SEARCHENGINE_URL       =
+
+# When SERVER_BASED_SEARCH and EXTERNAL_SEARCH are both enabled the unindexed
+# search data is written to a file for indexing by an external tool. With the
+# SEARCHDATA_FILE tag the name of this file can be specified.
+# The default file is: searchdata.xml.
+# This tag requires that the tag SEARCHENGINE is set to YES.
+
+SEARCHDATA_FILE        = searchdata.xml
+
+# When SERVER_BASED_SEARCH and EXTERNAL_SEARCH are both enabled the
+# EXTERNAL_SEARCH_ID tag can be used as an identifier for the project. This is
+# useful in combination with EXTRA_SEARCH_MAPPINGS to search through multiple
+# projects and redirect the results back to the right project.
+# This tag requires that the tag SEARCHENGINE is set to YES.
+
+EXTERNAL_SEARCH_ID     =
+
+# The EXTRA_SEARCH_MAPPINGS tag can be used to enable searching through doxygen
+# projects other than the one defined by this configuration file, but that are
+# all added to the same external search index. Each project needs to have a
+# unique id set via EXTERNAL_SEARCH_ID. The search mapping then maps the id of
+# to a relative location where the documentation can be found. The format is:
+# EXTRA_SEARCH_MAPPINGS = tagname1=loc1 tagname2=loc2 ...
+# This tag requires that the tag SEARCHENGINE is set to YES.
+
+EXTRA_SEARCH_MAPPINGS  =
+
+#---------------------------------------------------------------------------
+# Configuration options related to the LaTeX output
+#---------------------------------------------------------------------------
+
+# If the GENERATE_LATEX tag is set to YES, doxygen will generate LaTeX output.
+# The default value is: YES.
+
+GENERATE_LATEX         = NO
+
+# The LATEX_OUTPUT tag is used to specify where the LaTeX docs will be put. If a
+# relative path is entered the value of OUTPUT_DIRECTORY will be put in front of
+# it.
+# The default directory is: latex.
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+LATEX_OUTPUT           = latex
+
+# The LATEX_CMD_NAME tag can be used to specify the LaTeX command name to be
+# invoked.
+#
+# Note that when not enabling USE_PDFLATEX the default is latex when enabling
+# USE_PDFLATEX the default is pdflatex and when in the later case latex is
+# chosen this is overwritten by pdflatex. For specific output languages the
+# default can have been set differently, this depends on the implementation of
+# the output language.
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+LATEX_CMD_NAME         =
+
+# The MAKEINDEX_CMD_NAME tag can be used to specify the command name to generate
+# index for LaTeX.
+# Note: This tag is used in the Makefile / make.bat.
+# See also: LATEX_MAKEINDEX_CMD for the part in the generated output file
+# (.tex).
+# The default file is: makeindex.
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+MAKEINDEX_CMD_NAME     = makeindex
+
+# The LATEX_MAKEINDEX_CMD tag can be used to specify the command name to
+# generate index for LaTeX. In case there is no backslash (\) as first character
+# it will be automatically added in the LaTeX code.
+# Note: This tag is used in the generated output file (.tex).
+# See also: MAKEINDEX_CMD_NAME for the part in the Makefile / make.bat.
+# The default value is: makeindex.
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+LATEX_MAKEINDEX_CMD    = makeindex
+
+# If the COMPACT_LATEX tag is set to YES, doxygen generates more compact LaTeX
+# documents. This may be useful for small projects and may help to save some
+# trees in general.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+COMPACT_LATEX          = NO
+
+# The PAPER_TYPE tag can be used to set the paper type that is used by the
+# printer.
+# Possible values are: a4 (210 x 297 mm), letter (8.5 x 11 inches), legal (8.5 x
+# 14 inches) and executive (7.25 x 10.5 inches).
+# The default value is: a4.
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+PAPER_TYPE             = a4
+
+# The EXTRA_PACKAGES tag can be used to specify one or more LaTeX package names
+# that should be included in the LaTeX output. The package can be specified just
+# by its name or with the correct syntax as to be used with the LaTeX
+# \usepackage command. To get the times font for instance you can specify :
+# EXTRA_PACKAGES=times or EXTRA_PACKAGES={times}
+# To use the option intlimits with the amsmath package you can specify:
+# EXTRA_PACKAGES=[intlimits]{amsmath}
+# If left blank no extra packages will be included.
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+EXTRA_PACKAGES         =
+
+# The LATEX_HEADER tag can be used to specify a user-defined LaTeX header for
+# the generated LaTeX document. The header should contain everything until the
+# first chapter. If it is left blank doxygen will generate a standard header. It
+# is highly recommended to start with a default header using
+# doxygen -w latex new_header.tex new_footer.tex new_stylesheet.sty
+# and then modify the file new_header.tex. See also section "Doxygen usage" for
+# information on how to generate the default header that doxygen normally uses.
+#
+# Note: Only use a user-defined header if you know what you are doing!
+# Note: The header is subject to change so you typically have to regenerate the
+# default header when upgrading to a newer version of doxygen. The following
+# commands have a special meaning inside the header (and footer): For a
+# description of the possible markers and block names see the documentation.
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+LATEX_HEADER           =
+
+# The LATEX_FOOTER tag can be used to specify a user-defined LaTeX footer for
+# the generated LaTeX document. The footer should contain everything after the
+# last chapter. If it is left blank doxygen will generate a standard footer. See
+# LATEX_HEADER for more information on how to generate a default footer and what
+# special commands can be used inside the footer. See also section "Doxygen
+# usage" for information on how to generate the default footer that doxygen
+# normally uses. Note: Only use a user-defined footer if you know what you are
+# doing!
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+LATEX_FOOTER           =
+
+# The LATEX_EXTRA_STYLESHEET tag can be used to specify additional user-defined
+# LaTeX style sheets that are included after the standard style sheets created
+# by doxygen. Using this option one can overrule certain style aspects. Doxygen
+# will copy the style sheet files to the output directory.
+# Note: The order of the extra style sheet files is of importance (e.g. the last
+# style sheet in the list overrules the setting of the previous ones in the
+# list).
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+LATEX_EXTRA_STYLESHEET =
+
+# The LATEX_EXTRA_FILES tag can be used to specify one or more extra images or
+# other source files which should be copied to the LATEX_OUTPUT output
+# directory. Note that the files will be copied as-is; there are no commands or
+# markers available.
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+LATEX_EXTRA_FILES      =
+
+# If the PDF_HYPERLINKS tag is set to YES, the LaTeX that is generated is
+# prepared for conversion to PDF (using ps2pdf or pdflatex). The PDF file will
+# contain links (just like the HTML output) instead of page references. This
+# makes the output suitable for online browsing using a PDF viewer.
+# The default value is: YES.
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+PDF_HYPERLINKS         = YES
+
+# If the USE_PDFLATEX tag is set to YES, doxygen will use the engine as
+# specified with LATEX_CMD_NAME to generate the PDF file directly from the LaTeX
+# files. Set this option to YES, to get a higher quality PDF documentation.
+#
+# See also section LATEX_CMD_NAME for selecting the engine.
+# The default value is: YES.
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+USE_PDFLATEX           = YES
+
+# If the LATEX_BATCHMODE tag is set to YES, doxygen will add the \batchmode
+# command to the generated LaTeX files. This will instruct LaTeX to keep running
+# if errors occur, instead of asking the user for help.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+LATEX_BATCHMODE        = NO
+
+# If the LATEX_HIDE_INDICES tag is set to YES then doxygen will not include the
+# index chapters (such as File Index, Compound Index, etc.) in the output.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+LATEX_HIDE_INDICES     = NO
+
+# The LATEX_BIB_STYLE tag can be used to specify the style to use for the
+# bibliography, e.g. plainnat, or ieeetr. See
+# https://en.wikipedia.org/wiki/BibTeX and \cite for more info.
+# The default value is: plain.
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+LATEX_BIB_STYLE        = plain
+
+# If the LATEX_TIMESTAMP tag is set to YES then the footer of each generated
+# page will contain the date and time when the page was generated. Setting this
+# to NO can help when comparing the output of multiple runs.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+LATEX_TIMESTAMP        = NO
+
+# The LATEX_EMOJI_DIRECTORY tag is used to specify the (relative or absolute)
+# path from which the emoji images will be read. If a relative path is entered,
+# it will be relative to the LATEX_OUTPUT directory. If left blank the
+# LATEX_OUTPUT directory will be used.
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+LATEX_EMOJI_DIRECTORY  =
+
+#---------------------------------------------------------------------------
+# Configuration options related to the RTF output
+#---------------------------------------------------------------------------
+
+# If the GENERATE_RTF tag is set to YES, doxygen will generate RTF output. The
+# RTF output is optimized for Word 97 and may not look too pretty with other RTF
+# readers/editors.
+# The default value is: NO.
+
+GENERATE_RTF           = NO
+
+# The RTF_OUTPUT tag is used to specify where the RTF docs will be put. If a
+# relative path is entered the value of OUTPUT_DIRECTORY will be put in front of
+# it.
+# The default directory is: rtf.
+# This tag requires that the tag GENERATE_RTF is set to YES.
+
+RTF_OUTPUT             = rtf
+
+# If the COMPACT_RTF tag is set to YES, doxygen generates more compact RTF
+# documents. This may be useful for small projects and may help to save some
+# trees in general.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_RTF is set to YES.
+
+COMPACT_RTF            = NO
+
+# If the RTF_HYPERLINKS tag is set to YES, the RTF that is generated will
+# contain hyperlink fields. The RTF file will contain links (just like the HTML
+# output) instead of page references. This makes the output suitable for online
+# browsing using Word or some other Word compatible readers that support those
+# fields.
+#
+# Note: WordPad (write) and others do not support links.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_RTF is set to YES.
+
+RTF_HYPERLINKS         = NO
+
+# Load stylesheet definitions from file. Syntax is similar to doxygen's
+# configuration file, i.e. a series of assignments. You only have to provide
+# replacements, missing definitions are set to their default value.
+#
+# See also section "Doxygen usage" for information on how to generate the
+# default style sheet that doxygen normally uses.
+# This tag requires that the tag GENERATE_RTF is set to YES.
+
+RTF_STYLESHEET_FILE    =
+
+# Set optional variables used in the generation of an RTF document. Syntax is
+# similar to doxygen's configuration file. A template extensions file can be
+# generated using doxygen -e rtf extensionFile.
+# This tag requires that the tag GENERATE_RTF is set to YES.
+
+RTF_EXTENSIONS_FILE    =
+
+#---------------------------------------------------------------------------
+# Configuration options related to the man page output
+#---------------------------------------------------------------------------
+
+# If the GENERATE_MAN tag is set to YES, doxygen will generate man pages for
+# classes and files.
+# The default value is: NO.
+
+GENERATE_MAN           = NO
+
+# The MAN_OUTPUT tag is used to specify where the man pages will be put. If a
+# relative path is entered the value of OUTPUT_DIRECTORY will be put in front of
+# it. A directory man3 will be created inside the directory specified by
+# MAN_OUTPUT.
+# The default directory is: man.
+# This tag requires that the tag GENERATE_MAN is set to YES.
+
+MAN_OUTPUT             = man
+
+# The MAN_EXTENSION tag determines the extension that is added to the generated
+# man pages. In case the manual section does not start with a number, the number
+# 3 is prepended. The dot (.) at the beginning of the MAN_EXTENSION tag is
+# optional.
+# The default value is: .3.
+# This tag requires that the tag GENERATE_MAN is set to YES.
+
+MAN_EXTENSION          = .3
+
+# The MAN_SUBDIR tag determines the name of the directory created within
+# MAN_OUTPUT in which the man pages are placed. If defaults to man followed by
+# MAN_EXTENSION with the initial . removed.
+# This tag requires that the tag GENERATE_MAN is set to YES.
+
+MAN_SUBDIR             =
+
+# If the MAN_LINKS tag is set to YES and doxygen generates man output, then it
+# will generate one additional man file for each entity documented in the real
+# man page(s). These additional files only source the real man page, but without
+# them the man command would be unable to find the correct page.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_MAN is set to YES.
+
+MAN_LINKS              = NO
+
+#---------------------------------------------------------------------------
+# Configuration options related to the XML output
+#---------------------------------------------------------------------------
+
+# If the GENERATE_XML tag is set to YES, doxygen will generate an XML file that
+# captures the structure of the code including all documentation.
+# The default value is: NO.
+
+GENERATE_XML           = NO
+
+# The XML_OUTPUT tag is used to specify where the XML pages will be put. If a
+# relative path is entered the value of OUTPUT_DIRECTORY will be put in front of
+# it.
+# The default directory is: xml.
+# This tag requires that the tag GENERATE_XML is set to YES.
+
+XML_OUTPUT             = xml
+
+# If the XML_PROGRAMLISTING tag is set to YES, doxygen will dump the program
+# listings (including syntax highlighting and cross-referencing information) to
+# the XML output. Note that enabling this will significantly increase the size
+# of the XML output.
+# The default value is: YES.
+# This tag requires that the tag GENERATE_XML is set to YES.
+
+XML_PROGRAMLISTING     = YES
+
+# If the XML_NS_MEMB_FILE_SCOPE tag is set to YES, doxygen will include
+# namespace members in file scope as well, matching the HTML output.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_XML is set to YES.
+
+XML_NS_MEMB_FILE_SCOPE = NO
+
+#---------------------------------------------------------------------------
+# Configuration options related to the DOCBOOK output
+#---------------------------------------------------------------------------
+
+# If the GENERATE_DOCBOOK tag is set to YES, doxygen will generate Docbook files
+# that can be used to generate PDF.
+# The default value is: NO.
+
+GENERATE_DOCBOOK       = NO
+
+# The DOCBOOK_OUTPUT tag is used to specify where the Docbook pages will be put.
+# If a relative path is entered the value of OUTPUT_DIRECTORY will be put in
+# front of it.
+# The default directory is: docbook.
+# This tag requires that the tag GENERATE_DOCBOOK is set to YES.
+
+DOCBOOK_OUTPUT         = docbook
+
+#---------------------------------------------------------------------------
+# Configuration options for the AutoGen Definitions output
+#---------------------------------------------------------------------------
+
+# If the GENERATE_AUTOGEN_DEF tag is set to YES, doxygen will generate an
+# AutoGen Definitions (see http://autogen.sourceforge.net/) file that captures
+# the structure of the code including all documentation. Note that this feature
+# is still experimental and incomplete at the moment.
+# The default value is: NO.
+
+GENERATE_AUTOGEN_DEF   = NO
+
+#---------------------------------------------------------------------------
+# Configuration options related to Sqlite3 output
+#---------------------------------------------------------------------------
+
+#---------------------------------------------------------------------------
+# Configuration options related to the Perl module output
+#---------------------------------------------------------------------------
+
+# If the GENERATE_PERLMOD tag is set to YES, doxygen will generate a Perl module
+# file that captures the structure of the code including all documentation.
+#
+# Note that this feature is still experimental and incomplete at the moment.
+# The default value is: NO.
+
+GENERATE_PERLMOD       = NO
+
+# If the PERLMOD_LATEX tag is set to YES, doxygen will generate the necessary
+# Makefile rules, Perl scripts and LaTeX code to be able to generate PDF and DVI
+# output from the Perl module output.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_PERLMOD is set to YES.
+
+PERLMOD_LATEX          = NO
+
+# If the PERLMOD_PRETTY tag is set to YES, the Perl module output will be nicely
+# formatted so it can be parsed by a human reader. This is useful if you want to
+# understand what is going on. On the other hand, if this tag is set to NO, the
+# size of the Perl module output will be much smaller and Perl will parse it
+# just the same.
+# The default value is: YES.
+# This tag requires that the tag GENERATE_PERLMOD is set to YES.
+
+PERLMOD_PRETTY         = YES
+
+# The names of the make variables in the generated doxyrules.make file are
+# prefixed with the string contained in PERLMOD_MAKEVAR_PREFIX. This is useful
+# so different doxyrules.make files included by the same Makefile don't
+# overwrite each other's variables.
+# This tag requires that the tag GENERATE_PERLMOD is set to YES.
+
+PERLMOD_MAKEVAR_PREFIX =
+
+#---------------------------------------------------------------------------
+# Configuration options related to the preprocessor
+#---------------------------------------------------------------------------
+
+# If the ENABLE_PREPROCESSING tag is set to YES, doxygen will evaluate all
+# C-preprocessor directives found in the sources and include files.
+# The default value is: YES.
+
+ENABLE_PREPROCESSING   = NO
+
+# If the MACRO_EXPANSION tag is set to YES, doxygen will expand all macro names
+# in the source code. If set to NO, only conditional compilation will be
+# performed. Macro expansion can be done in a controlled way by setting
+# EXPAND_ONLY_PREDEF to YES.
+# The default value is: NO.
+# This tag requires that the tag ENABLE_PREPROCESSING is set to YES.
+
+MACRO_EXPANSION        = NO
+
+# If the EXPAND_ONLY_PREDEF and MACRO_EXPANSION tags are both set to YES then
+# the macro expansion is limited to the macros specified with the PREDEFINED and
+# EXPAND_AS_DEFINED tags.
+# The default value is: NO.
+# This tag requires that the tag ENABLE_PREPROCESSING is set to YES.
+
+EXPAND_ONLY_PREDEF     = NO
+
+# If the SEARCH_INCLUDES tag is set to YES, the include files in the
+# INCLUDE_PATH will be searched if a #include is found.
+# The default value is: YES.
+# This tag requires that the tag ENABLE_PREPROCESSING is set to YES.
+
+SEARCH_INCLUDES        = YES
+
+# The INCLUDE_PATH tag can be used to specify one or more directories that
+# contain include files that are not input files but should be processed by the
+# preprocessor.
+# This tag requires that the tag SEARCH_INCLUDES is set to YES.
+
+INCLUDE_PATH           =
+
+# You can use the INCLUDE_FILE_PATTERNS tag to specify one or more wildcard
+# patterns (like *.h and *.hpp) to filter out the header-files in the
+# directories. If left blank, the patterns specified with FILE_PATTERNS will be
+# used.
+# This tag requires that the tag ENABLE_PREPROCESSING is set to YES.
+
+INCLUDE_FILE_PATTERNS  =
+
+# The PREDEFINED tag can be used to specify one or more macro names that are
+# defined before the preprocessor is started (similar to the -D option of e.g.
+# gcc). The argument of the tag is a list of macros of the form: name or
+# name=definition (no spaces). If the definition and the "=" are omitted, "=1"
+# is assumed. To prevent a macro definition from being undefined via #undef or
+# recursively expanded use the := operator instead of the = operator.
+# This tag requires that the tag ENABLE_PREPROCESSING is set to YES.
+
+PREDEFINED             =
+
+# If the MACRO_EXPANSION and EXPAND_ONLY_PREDEF tags are set to YES then this
+# tag can be used to specify a list of macro names that should be expanded. The
+# macro definition that is found in the sources will be used. Use the PREDEFINED
+# tag if you want to use a different macro definition that overrules the
+# definition found in the source code.
+# This tag requires that the tag ENABLE_PREPROCESSING is set to YES.
+
+EXPAND_AS_DEFINED      =
+
+# If the SKIP_FUNCTION_MACROS tag is set to YES then doxygen's preprocessor will
+# remove all references to function-like macros that are alone on a line, have
+# an all uppercase name, and do not end with a semicolon. Such function macros
+# are typically used for boiler-plate code, and will confuse the parser if not
+# removed.
+# The default value is: YES.
+# This tag requires that the tag ENABLE_PREPROCESSING is set to YES.
+
+SKIP_FUNCTION_MACROS   = YES
+
+#---------------------------------------------------------------------------
+# Configuration options related to external references
+#---------------------------------------------------------------------------
+
+# The TAGFILES tag can be used to specify one or more tag files. For each tag
+# file the location of the external documentation should be added. The format of
+# a tag file without this location is as follows:
+# TAGFILES = file1 file2 ...
+# Adding location for the tag files is done as follows:
+# TAGFILES = file1=loc1 "file2 = loc2" ...
+# where loc1 and loc2 can be relative or absolute paths or URLs. See the
+# section "Linking to external documentation" for more information about the use
+# of tag files.
+# Note: Each tag file must have a unique name (where the name does NOT include
+# the path). If a tag file is not located in the directory in which doxygen is
+# run, you must also specify the path to the tagfile here.
+
+TAGFILES               =
+
+# When a file name is specified after GENERATE_TAGFILE, doxygen will create a
+# tag file that is based on the input files it reads. See section "Linking to
+# external documentation" for more information about the usage of tag files.
+
+GENERATE_TAGFILE       =
+
+# If the ALLEXTERNALS tag is set to YES, all external class will be listed in
+# the class index. If set to NO, only the inherited external classes will be
+# listed.
+# The default value is: NO.
+
+ALLEXTERNALS           = NO
+
+# If the EXTERNAL_GROUPS tag is set to YES, all external groups will be listed
+# in the modules index. If set to NO, only the current project's groups will be
+# listed.
+# The default value is: YES.
+
+EXTERNAL_GROUPS        = YES
+
+# If the EXTERNAL_PAGES tag is set to YES, all external pages will be listed in
+# the related pages index. If set to NO, only the current project's pages will
+# be listed.
+# The default value is: YES.
+
+EXTERNAL_PAGES         = YES
+
+#---------------------------------------------------------------------------
+# Configuration options related to the dot tool
+#---------------------------------------------------------------------------
+
+# You can include diagrams made with dia in doxygen documentation. Doxygen will
+# then run dia to produce the diagram and insert it in the documentation. The
+# DIA_PATH tag allows you to specify the directory where the dia binary resides.
+# If left empty dia is assumed to be found in the default search path.
+
+DIA_PATH               =
+
+# If set to YES the inheritance and collaboration graphs will hide inheritance
+# and usage relations if the target is undocumented or is not a class.
+# The default value is: YES.
+
+HIDE_UNDOC_RELATIONS   = YES
+
+# If you set the HAVE_DOT tag to YES then doxygen will assume the dot tool is
+# available from the path. This tool is part of Graphviz (see:
+# http://www.graphviz.org/), a graph visualization toolkit from AT&T and Lucent
+# Bell Labs. The other options in this section have no effect if this option is
+# set to NO
+# The default value is: NO.
+
+HAVE_DOT               = YES
+
+# The DOT_NUM_THREADS specifies the number of dot invocations doxygen is allowed
+# to run in parallel. When set to 0 doxygen will base this on the number of
+# processors available in the system. You can set it explicitly to a value
+# larger than 0 to get control over the balance between CPU load and processing
+# speed.
+# Minimum value: 0, maximum value: 32, default value: 0.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+DOT_NUM_THREADS        = 0
+
+# When you want a differently looking font in the dot files that doxygen
+# generates you can specify the font name using DOT_FONTNAME. You need to make
+# sure dot is able to find the font, which can be done by putting it in a
+# standard location or by setting the DOTFONTPATH environment variable or by
+# setting DOT_FONTPATH to the directory containing the font.
+# The default value is: Helvetica.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+DOT_FONTNAME           = Helvetica
+
+# The DOT_FONTSIZE tag can be used to set the size (in points) of the font of
+# dot graphs.
+# Minimum value: 4, maximum value: 24, default value: 10.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+DOT_FONTSIZE           = 10
+
+# By default doxygen will tell dot to use the default font as specified with
+# DOT_FONTNAME. If you specify a different font using DOT_FONTNAME you can set
+# the path where dot can find it using this tag.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+DOT_FONTPATH           =
+
+# If the CLASS_GRAPH tag is set to YES (or GRAPH) then doxygen will generate a
+# graph for each documented class showing the direct and indirect inheritance
+# relations. In case HAVE_DOT is set as well dot will be used to draw the graph,
+# otherwise the built-in generator will be used. If the CLASS_GRAPH tag is set
+# to TEXT the direct and indirect inheritance relations will be shown as texts /
+# links.
+# Possible values are: NO, YES, TEXT and GRAPH.
+# The default value is: YES.
+
+CLASS_GRAPH            = NO
+
+# If the COLLABORATION_GRAPH tag is set to YES then doxygen will generate a
+# graph for each documented class showing the direct and indirect implementation
+# dependencies (inheritance, containment, and class references variables) of the
+# class with other documented classes.
+# The default value is: YES.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+COLLABORATION_GRAPH    = YES
+
+# If the GROUP_GRAPHS tag is set to YES then doxygen will generate a graph for
+# groups, showing the direct groups dependencies.
+# The default value is: YES.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+GROUP_GRAPHS           = YES
+
+# If the UML_LOOK tag is set to YES, doxygen will generate inheritance and
+# collaboration diagrams in a style similar to the OMG's Unified Modeling
+# Language.
+# The default value is: NO.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+UML_LOOK               = NO
+
+# If the UML_LOOK tag is enabled, the fields and methods are shown inside the
+# class node. If there are many fields or methods and many nodes the graph may
+# become too big to be useful. The UML_LIMIT_NUM_FIELDS threshold limits the
+# number of items for each type to make the size more manageable. Set this to 0
+# for no limit. Note that the threshold may be exceeded by 50% before the limit
+# is enforced. So when you set the threshold to 10, up to 15 fields may appear,
+# but if the number exceeds 15, the total amount of fields shown is limited to
+# 10.
+# Minimum value: 0, maximum value: 100, default value: 10.
+# This tag requires that the tag UML_LOOK is set to YES.
+
+UML_LIMIT_NUM_FIELDS   = 10
+
+# If the DOT_UML_DETAILS tag is set to NO, doxygen will show attributes and
+# methods without types and arguments in the UML graphs. If the DOT_UML_DETAILS
+# tag is set to YES, doxygen will add type and arguments for attributes and
+# methods in the UML graphs. If the DOT_UML_DETAILS tag is set to NONE, doxygen
+# will not generate fields with class member information in the UML graphs. The
+# class diagrams will look similar to the default class diagrams but using UML
+# notation for the relationships.
+# Possible values are: NO, YES and NONE.
+# The default value is: NO.
+# This tag requires that the tag UML_LOOK is set to YES.
+
+DOT_UML_DETAILS        = NO
+
+# The DOT_WRAP_THRESHOLD tag can be used to set the maximum number of characters
+# to display on a single line. If the actual line length exceeds this threshold
+# significantly it will wrapped across multiple lines. Some heuristics are apply
+# to avoid ugly line breaks.
+# Minimum value: 0, maximum value: 1000, default value: 17.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+DOT_WRAP_THRESHOLD     = 17
+
+# If the TEMPLATE_RELATIONS tag is set to YES then the inheritance and
+# collaboration graphs will show the relations between templates and their
+# instances.
+# The default value is: NO.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+TEMPLATE_RELATIONS     = NO
+
+# If the INCLUDE_GRAPH, ENABLE_PREPROCESSING and SEARCH_INCLUDES tags are set to
+# YES then doxygen will generate a graph for each documented file showing the
+# direct and indirect include dependencies of the file with other documented
+# files.
+# The default value is: YES.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+INCLUDE_GRAPH          = YES
+
+# If the INCLUDED_BY_GRAPH, ENABLE_PREPROCESSING and SEARCH_INCLUDES tags are
+# set to YES then doxygen will generate a graph for each documented file showing
+# the direct and indirect include dependencies of the file with other documented
+# files.
+# The default value is: YES.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+INCLUDED_BY_GRAPH      = YES
+
+# If the CALL_GRAPH tag is set to YES then doxygen will generate a call
+# dependency graph for every global function or class method.
+#
+# Note that enabling this option will significantly increase the time of a run.
+# So in most cases it will be better to enable call graphs for selected
+# functions only using the \callgraph command. Disabling a call graph can be
+# accomplished by means of the command \hidecallgraph.
+# The default value is: NO.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+CALL_GRAPH             = NO
+
+# If the CALLER_GRAPH tag is set to YES then doxygen will generate a caller
+# dependency graph for every global function or class method.
+#
+# Note that enabling this option will significantly increase the time of a run.
+# So in most cases it will be better to enable caller graphs for selected
+# functions only using the \callergraph command. Disabling a caller graph can be
+# accomplished by means of the command \hidecallergraph.
+# The default value is: NO.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+CALLER_GRAPH           = NO
+
+# If the GRAPHICAL_HIERARCHY tag is set to YES then doxygen will graphical
+# hierarchy of all classes instead of a textual one.
+# The default value is: YES.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+GRAPHICAL_HIERARCHY    = YES
+
+# If the DIRECTORY_GRAPH tag is set to YES then doxygen will show the
+# dependencies a directory has on other directories in a graphical way. The
+# dependency relations are determined by the #include relations between the
+# files in the directories.
+# The default value is: YES.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+DIRECTORY_GRAPH        = YES
+
+# The DIR_GRAPH_MAX_DEPTH tag can be used to limit the maximum number of levels
+# of child directories generated in directory dependency graphs by dot.
+# Minimum value: 1, maximum value: 25, default value: 1.
+# This tag requires that the tag DIRECTORY_GRAPH is set to YES.
+
+DIR_GRAPH_MAX_DEPTH    = 1
+
+# The DOT_IMAGE_FORMAT tag can be used to set the image format of the images
+# generated by dot. For an explanation of the image formats see the section
+# output formats in the documentation of the dot tool (Graphviz (see:
+# http://www.graphviz.org/)).
+# Note: If you choose svg you need to set HTML_FILE_EXTENSION to xhtml in order
+# to make the SVG files visible in IE 9+ (other browsers do not have this
+# requirement).
+# Possible values are: png, jpg, gif, svg, png:gd, png:gd:gd, png:cairo,
+# png:cairo:gd, png:cairo:cairo, png:cairo:gdiplus, png:gdiplus and
+# png:gdiplus:gdiplus.
+# The default value is: png.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+DOT_IMAGE_FORMAT       = png
+
+# If DOT_IMAGE_FORMAT is set to svg, then this option can be set to YES to
+# enable generation of interactive SVG images that allow zooming and panning.
+#
+# Note that this requires a modern browser other than Internet Explorer. Tested
+# and working are Firefox, Chrome, Safari, and Opera.
+# Note: For IE 9+ you need to set HTML_FILE_EXTENSION to xhtml in order to make
+# the SVG files visible. Older versions of IE do not have SVG support.
+# The default value is: NO.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+INTERACTIVE_SVG        = NO
+
+# The DOT_PATH tag can be used to specify the path where the dot tool can be
+# found. If left blank, it is assumed the dot tool can be found in the path.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+DOT_PATH               =
+
+# The DOTFILE_DIRS tag can be used to specify one or more directories that
+# contain dot files that are included in the documentation (see the \dotfile
+# command).
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+DOTFILE_DIRS           =
+
+# The MSCFILE_DIRS tag can be used to specify one or more directories that
+# contain msc files that are included in the documentation (see the \mscfile
+# command).
+
+MSCFILE_DIRS           =
+
+# The DIAFILE_DIRS tag can be used to specify one or more directories that
+# contain dia files that are included in the documentation (see the \diafile
+# command).
+
+DIAFILE_DIRS           =
+
+# When using plantuml, the PLANTUML_JAR_PATH tag should be used to specify the
+# path where java can find the plantuml.jar file or to the filename of jar file
+# to be used. If left blank, it is assumed PlantUML is not used or called during
+# a preprocessing step. Doxygen will generate a warning when it encounters a
+# \startuml command in this case and will not generate output for the diagram.
+
+PLANTUML_JAR_PATH      =
+
+# When using plantuml, the PLANTUML_CFG_FILE tag can be used to specify a
+# configuration file for plantuml.
+
+PLANTUML_CFG_FILE      =
+
+# When using plantuml, the specified paths are searched for files specified by
+# the !include statement in a plantuml block.
+
+PLANTUML_INCLUDE_PATH  =
+
+# The DOT_GRAPH_MAX_NODES tag can be used to set the maximum number of nodes
+# that will be shown in the graph. If the number of nodes in a graph becomes
+# larger than this value, doxygen will truncate the graph, which is visualized
+# by representing a node as a red box. Note that doxygen if the number of direct
+# children of the root node in a graph is already larger than
+# DOT_GRAPH_MAX_NODES then the graph will not be shown at all. Also note that
+# the size of a graph can be further restricted by MAX_DOT_GRAPH_DEPTH.
+# Minimum value: 0, maximum value: 10000, default value: 50.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+DOT_GRAPH_MAX_NODES    = 50
+
+# The MAX_DOT_GRAPH_DEPTH tag can be used to set the maximum depth of the graphs
+# generated by dot. A depth value of 3 means that only nodes reachable from the
+# root by following a path via at most 3 edges will be shown. Nodes that lay
+# further from the root node will be omitted. Note that setting this option to 1
+# or 2 may greatly reduce the computation time needed for large code bases. Also
+# note that the size of a graph can be further restricted by
+# DOT_GRAPH_MAX_NODES. Using a depth of 0 means no depth restriction.
+# Minimum value: 0, maximum value: 1000, default value: 0.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+MAX_DOT_GRAPH_DEPTH    = 0
+
+# Set the DOT_TRANSPARENT tag to YES to generate images with a transparent
+# background. This is disabled by default, because dot on Windows does not seem
+# to support this out of the box.
+#
+# Warning: Depending on the platform used, enabling this option may lead to
+# badly anti-aliased labels on the edges of a graph (i.e. they become hard to
+# read).
+# The default value is: NO.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+DOT_TRANSPARENT        = NO
+
+# Set the DOT_MULTI_TARGETS tag to YES to allow dot to generate multiple output
+# files in one run (i.e. multiple -o and -T options on the command line). This
+# makes dot run faster, but since only newer versions of dot (>1.8.10) support
+# this, this feature is disabled by default.
+# The default value is: NO.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+DOT_MULTI_TARGETS      = NO
+
+# If the GENERATE_LEGEND tag is set to YES doxygen will generate a legend page
+# explaining the meaning of the various boxes and arrows in the dot generated
+# graphs.
+# Note: This tag requires that UML_LOOK isn't set, i.e. the doxygen internal
+# graphical representation for inheritance and collaboration diagrams is used.
+# The default value is: YES.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+GENERATE_LEGEND        = YES
+
+# If the DOT_CLEANUP tag is set to YES, doxygen will remove the intermediate
+# files that are used to generate the various graphs.
+#
+# Note: This setting is not only used for dot files but also for msc temporary
+# files.
+# The default value is: YES.
+
+DOT_CLEANUP            = YES

TODO.md

@@ -22,6 +22,7 @@
     - *D* Subclass term types
 - *D* Namespaced IRIs
 - *D* Relative IRIs
+- D Flexible store interface
 - *P* Transaction control
 - *P* Turtle serialization / deserialization
 - *P* Full UTF-8 support

cpython/py_graph.h

@@ -155,7 +155,25 @@ Graph_init (GraphObject *self, PyObject *args, PyObject *kwargs)
 
     } else uri = LSUP_iriref_new (NULL, NULL);
 
-    self->ob_struct = LSUP_graph_new (uri, (LSUP_store_type) store_type);
+    // Set up the store if a function for that is defined.
+    const LSUP_StoreInt *sif = LSUP_store_int (store_type);
+    if (UNLIKELY (!sif)) {
+            PyErr_SetString (
+                    PyExc_TypeError,
+                    "No interface defined for given store type.");
+            return -1;
+    }
+    if (sif->setup_fn) {
+        if (sif->setup_fn(NULL, false) < LSUP_OK) {
+            PyErr_SetString (
+                    PyExc_IOError, "Error initializing back end store.");
+            return -1;
+        }
+    }
+
+    // TODO Make store ID, nsm and initial size accessible.
+    self->ob_struct = LSUP_graph_new (
+            uri, (LSUP_StoreType) store_type, NULL, NULL, 0);
     if (!self->ob_struct) {
         PyErr_SetString (PyExc_ValueError, "Could not create graph.");
         return -1;
@@ -210,21 +228,20 @@ static PyGetSetDef Graph_getsetters[] = {
 };
 
 
-static PyObject *
-Graph_copy (PyTypeObject *cls, PyObject *src)
+static int
+Graph_copy_contents (GraphObject *self, GraphObject *dest)
 {
-    if (! PyObject_TypeCheck (src, cls)) return NULL;
-
-    GraphObject *res = (GraphObject *) cls->tp_alloc(cls, 0);
-    if (!res) return NULL;
-
-    res->ob_struct = LSUP_graph_copy (((GraphObject *) src)->ob_struct);
+    if (LSUP_graph_copy_contents (self->ob_struct, dest->ob_struct) < LSUP_OK)
+    {
+        PyErr_SetString (PyExc_ValueError, "Error copying graph contents.");
+        return -1;
+    }
 
-    Py_INCREF(res);
-    return (PyObject *) res;
+    return 0;
 };
 
 
+#if 0
 static PyObject *
 Graph_store (PyObject *self)
 {
@@ -232,7 +249,15 @@ Graph_store (PyObject *self)
             Py_TYPE (self), 0);
     if (!dest_obj) return PyErr_NoMemory();
 
-    LSUP_rc rc = LSUP_graph_store (
+    // TODO Make store ID, nsm and initial size accessible.
+    LSUP_Graph *dest = LSUP_graph_new (
+            uri, LSUP_STORE_HTABLE, NULL, NULL, 0);
+    if (!dest) {
+        PyErr_SetString (PyExc_ValueError, "Could not create graph.");
+        return -1;
+    }
+
+    LSUP_rc rc = LSUP_GraphStore (
             ((GraphObject *) self)->ob_struct, &((dest_obj)->ob_struct), NULL);
     if (rc != LSUP_OK) {
         log_error (LSUP_strerror (rc));
@@ -243,6 +268,7 @@ Graph_store (PyObject *self)
     Py_INCREF (dest_obj);
     return (PyObject *)dest_obj;
 }
+#endif
 
 
 static PyObject *
@@ -394,9 +420,20 @@ Graph_bool_op (
     GraphObject *res = (GraphObject *) cls->tp_alloc (cls, 0);
     if (!res) return NULL;
 
-    res->ob_struct = LSUP_graph_bool_op (
+    LSUP_Graph *dest = LSUP_graph_new (
+            NULL, LSUP_STORE_HTABLE, NULL, NULL, 0);
+    if (!dest) {
+        PyErr_SetString (PyExc_Exception, "Could not create destination graph.");
+        return NULL;
+    }
+
+    LSUP_rc rc = LSUP_graph_bool_op (
             op, ((GraphObject *) gr1)->ob_struct,
-            ((GraphObject *) gr2)->ob_struct);
+            ((GraphObject *) gr2)->ob_struct, res->ob_struct);
+    if (rc < LSUP_OK) {
+        PyErr_SetString (PyExc_Exception, "Error performing boolean operation.");
+        return NULL;
+    }
 
     Py_INCREF(res);
     return (PyObject *) res;
@@ -546,8 +583,8 @@ Graph_encode (PyObject *self, PyObject *args)
 
 static PyMethodDef Graph_methods[] = {
     {
-        "copy", (PyCFunction) Graph_copy, METH_CLASS | METH_VARARGS,
-        "Copy a graph."
+        "copy", (PyCFunction) Graph_copy_contents, METH_CLASS | METH_VARARGS,
+        "Copy the contents of a graph into another."
     },
     {
         "from_rdf", (PyCFunction) Graph_new_from_rdf,
@@ -561,10 +598,12 @@ static PyMethodDef Graph_methods[] = {
         "Create a set of graphs from a store SPO lookup."
     },
     */
+    /*
     {
         "store", (PyCFunction) Graph_store, METH_NOARGS,
         "Store a graph into the permanent back end."
     },
+    */
     {"add", (PyCFunction) Graph_add, METH_O, "Add triples to a graph."},
     {
         "remove", (PyCFunction) Graph_remove, METH_VARARGS,

cpython/py_lsup_rdf.c

@@ -181,7 +181,8 @@ PyInit_graph()
     if (!m) return NULL;
 
 #define ENTRY(a, b) \
-    if (PyModule_AddIntConstant (m, "STORE_" #a, b) < 0) return NULL;
+    if (PyModule_AddIntConstant (m, "STORE_" #a, LSUP_STORE_##a) < 0) \
+        return NULL;
     BACKEND_TBL
 #undef ENTRY
 

docs/dev/deps.dot

@@ -5,46 +5,44 @@ digraph "source tree" {
     fontsize="16";
     fontname="Helvetica";
 	clusterrank="local";
-	"codec_nt" -> "codec_base"
+	"py_term" -> "py_namespace"
 	"namespace" -> "core"
-	"buffer" -> "core"
-	"py_graph" -> "codec_nt"
-	"store_htable" -> "hashmap"
-	"core" -> "lmdb"
-	"graph" -> "environment"
-	"core" -> "xxhash"
-	"environment" -> "hashmap"
-	"graph" -> "store_htable"
-	"core" -> "log"
-	"codec_nt" -> "nt_parser"
 	"py_lsup_rdf" -> "py_namespace"
-	"graph" -> "term"
+	"store_htable" -> "store_base"
 	"store_mdb" -> "buffer"
-	"py_term" -> "py_namespace"
-	"environment" -> "store_mdb"
-	"store_mdb" -> "store"
-	"environment" -> "term"
-	"term" -> "hashmap"
-	"store_mdb" -> "namespace"
-	"graph" -> "store_mdb"
-	"term" -> "buffer"
-	"py_triple" -> "py_term"
-	"nt_parser" -> "nt_grammar"
-	"store_htable" -> "buffer"
-	"term" -> "namespace"
-	"lsup_rdf" -> "codec_nt"
-	"profile" -> "lsup_rdf"
-	"store_mdb" -> "lmdb"
-	"term" -> "tpl"
+	"py_term" -> "term"
+	"graph" -> "environment"
 	"py_graph" -> "py_triple"
-	"store_htable" -> "store"
+	"store_mdb" -> "lmdb"
+	"store_base" -> "environment"
+	"core" -> "lmdb"
+	"store_htable" -> "buffer"
+	"store_htable" -> "hashmap"
+	"py_triple" -> "py_term"
 	"py_namespace" -> "namespace"
-	"namespace" -> "hashmap"
-	"py_term" -> "term"
-	"store_mdb" -> "bootstrap"
-	"py_graph" -> "graph"
+	"term" -> "tpl"
 	"nt_parser" -> "graph"
+	"environment" -> "bootstrap"
+	"codec_nt" -> "codec_base"
+	"py_graph" -> "codec_nt"
+	"nt_grammar" -> "graph"
+	"graph" -> "store"
+	"environment" -> "term"
+	"store" -> "store_htable"
+	"graph" -> "term"
+	"codec_nt" -> "nt_parser"
+	"namespace" -> "hashmap"
 	"py_lsup_rdf" -> "py_graph"
+	"lsup_rdf" -> "codec_nt"
+	"core" -> "log"
+	"buffer" -> "core"
+	"term" -> "buffer"
+	"py_graph" -> "graph"
+	"store_mdb" -> "store_base"
+	"profile" -> "lsup_rdf"
+	"core" -> "xxhash"
+	"term" -> "namespace"
 	"codec_base" -> "graph"
-	"nt_grammar" -> "graph"
+	"store" -> "store_mdb"
+	"nt_parser" -> "nt_grammar"
 }

include/buffer.h

@@ -3,8 +3,10 @@
 
 #include "core.h"
 
-// "NULL" key, a value that is never user-provided. Used to mark special
-// values (e.g. deleted records).
+/** @brief "NULL" key, a value that is never user-provided.
+ *
+ * Used to mark special values (e.g. deleted records).
+ */
 #define NULL_KEY 0
 
 /** @brief General-purpose data buffer.
@@ -66,7 +68,7 @@ LSUP_buffer_init (LSUP_Buffer *buf, const size_t size, const void *data);
  *
  * To change the buffer size and/or data later call #LSUP_buffer_init.
  *
- * To copy a buffer just do buf2 = LSUP_buffer_new (buf1->size, buf1->addr);
+ * To copy a buffer just do buf2 = LSUP_buffer_new (buf1->addr, buf1->size);
  *
  * @param size[in] Length of the data.
  *
@@ -77,7 +79,7 @@ LSUP_buffer_init (LSUP_Buffer *buf, const size_t size, const void *data);
  *  on error.
  */
 inline LSUP_Buffer *
-LSUP_buffer_new (const size_t size, const void *data)
+LSUP_buffer_new (const void *data, const size_t size)
 {
     LSUP_Buffer *buf;
     CALLOC_GUARD (buf, NULL);
@@ -94,7 +96,7 @@ LSUP_buffer_new (const size_t size, const void *data)
 
 /** @brief Dummy buffer to be used with #LSUP_buffer_init.
  */
-#define BUF_DUMMY LSUP_buffer_new (0, NULL)
+#define BUF_DUMMY LSUP_buffer_new (NULL, 0)
 
 
 /** @brief Free the content of a buffer.
@@ -249,6 +251,6 @@ LSUP_btriple_hash (const LSUP_BufferTriple *strp)
 }
 
 
-#define STRP_DUMMY LSUP_btriple_new (NULL, NULL, NULL)
+#define BTRP_DUMMY LSUP_btriple_new (NULL, NULL, NULL)
 
 #endif

include/core.h

@@ -3,7 +3,6 @@
 
 #include <ctype.h>
 #include <dirent.h>
-#include <errno.h>
 #include <inttypes.h>
 #include <limits.h>
 #include <stdbool.h>
@@ -34,6 +33,8 @@
 #define LIKELY(x)       __builtin_expect(!!(x), true)
 #define UNLIKELY(x)     __builtin_expect(!!(x), false)
 
+#define LSUP_NS "urn:lsup:" /// Default LS namespace.
+
 // TODO Cross-platform ramdisk path.
 #define TMPDIR "/tmp"
 
@@ -175,10 +176,6 @@ extern char *warning_msg[], *error_msg[];
 
 extern char *LSUP_root_path;
 
-/** @brief Whether the environment is already initialized.
- */
-extern bool LSUP_env_is_init;
-
 
 typedef XXH32_hash_t LSUP_Hash32;
 typedef XXH64_hash_t LSUP_Hash64;
@@ -204,9 +201,12 @@ typedef char uuid_str_t[UUIDSTR_SIZE];
 
 /** @brief Make recursive directories.
  *
- * from https://gist.github.com/JonathonReinhart/8c0d90191c38af2dcadb102c4e202950
+ * Modified from
+ * https://gist.github.com/JonathonReinhart/8c0d90191c38af2dcadb102c4e202950
  */
-LSUP_rc mkdir_p(const char *path, mode_t mode);
+LSUP_rc
+mkdir_p (const char *path, mode_t mode);
+
 
 /** @brief Remove a directory recursively, as in Unix "rm -r".
  *
@@ -222,12 +222,13 @@ const char *
 LSUP_strerror (LSUP_rc rc);
 
 
-/**
- * Encode a code point using UTF-8
+/** @brief Encode a code point using UTF-8.
+ *
+ * https://gist.github.com/MightyPork/52eda3e5677b4b03524e40c9f0ab1da5
  *
  * @author Ondřej Hruška <ondra@ondrovo.com>
+ *
  * @license MIT
- * https://gist.github.com/MightyPork/52eda3e5677b4b03524e40c9f0ab1da5
  *
  * @param out - output buffer (min 5 characters), will be 0-terminated
  * @param utf - code point 0-0x10FFFF
@@ -277,23 +278,66 @@ inline int utf8_encode(const uint32_t utf, unsigned char *out)
 }
 
 
-// Error handling via goto.
-#define CHECK(exp, rc, marker) (rc) = (exp); if ((rc) != LSUP_OK) goto marker
+/** @brief Log an error or warning for return codes that are not LSUP_OK.
+ *
+ * Note that, if used outside of the other macros below, care must be taken
+ * to pass it an actual return code rather than an expression, otherwise the
+ * expression will be evaluated multiple times.
+ */
+#define LOG_RC(rc) do {                                             \
+    if ((rc) < 0) log_error (LSUP_strerror (rc));                   \
+    else if ((rc) > 0) log_warn (LSUP_strerror (rc));               \
+} while (0);
+
+/// Error handling via goto.
+#define CHECK(exp, marker) do {                                     \
+    LSUP_rc _rc = (exp);                                            \
+    LOG_RC(_rc);                                                    \
+    if (UNLIKELY (_rc != LSUP_OK)) goto marker;                     \
+} while (0);
 
-// Jump if rc is negative (skip warnings).
-#define PCHECK(exp, rc, marker) (rc) = (exp); if ((rc) < LSUP_OK) goto marker
+/// Jump if rc is negative (skip warnings).
+#define PCHECK(exp, marker) do {                                    \
+    LSUP_rc _rc = (exp);                                            \
+    LOG_RC(_rc);                                                    \
+    if (UNLIKELY (_rc < LSUP_OK)) goto marker;                      \
+} while (0);
 
-// Return rc if it is of LSUP_rc type and is negative (=error)
-#define RCCK(exp) LSUP_rc _rc = (exp); if (UNLIKELY (_rc < 0)) return _rc
+/// Return rc if it is of LSUP_rc type and nonzero.
+#define RCCK(exp) do {                                              \
+    LSUP_rc _rc = (exp);                                            \
+    LOG_RC(_rc);                                                    \
+    if (UNLIKELY (_rc != LSUP_OK)) return _rc;                       \
+} while (0);
 
-// Return NULL if it is of LSUP_rc type and is negative (=error)
-#define RCNL(exp) if (UNLIKELY ((exp) < 0)) return NULL
+/// Return rc if it is of LSUP_rc type and negative (=error)
+#define PRCCK(exp) do {                                              \
+    LSUP_rc _rc = (exp);                                            \
+    LOG_RC(_rc);                                                    \
+    if (UNLIKELY (_rc < LSUP_OK)) return _rc;                       \
+} while (0);
 
+/// Return NULL if RC is nonzero.
+#define RCNL(exp) do {                                              \
+    LSUP_rc _rc = (exp);                                            \
+    LOG_RC(_rc);                                                    \
+    if (UNLIKELY (_rc != LSUP_OK)) return NULL;                      \
+} while (0);
+
+/// Return NULL if RC is negative (=error)
+#define PRCNL(exp) do {                                              \
+    LSUP_rc _rc = (exp);                                            \
+    LOG_RC(_rc);                                                    \
+    if (UNLIKELY (_rc < LSUP_OK)) return NULL;                      \
+} while (0);
+
+/// Allocate one pointer with malloc and return rc if it fails.
 #define MALLOC_GUARD(var, rc) do {                                  \
     (var) = malloc (sizeof *(var));                                 \
     if (UNLIKELY (var == NULL)) return (rc);                        \
 } while (0);
 
+/// Allocate one pointer with calloc and return rc if it fails.
 #define CALLOC_GUARD(var, rc) do {                                  \
     (var) = calloc (1, sizeof *(var));                              \
     if (UNLIKELY (var == NULL)) return (rc);                        \
@@ -306,4 +350,4 @@ inline int utf8_encode(const uint32_t utf, unsigned char *out)
 #define CALLOC_GUARD_NL(var) CALLOC_GUARD((var), NULL)              \
 */
 
-#endif
+#endif  /* _LSUP_CORE_H */

include/data/bootstrap.h

@@ -1,13 +1,13 @@
 #ifndef LSUP_INIT_DATA_H
 #define LSUP_INIT_DATA_H
 
-
 /** @brief Initial namespace map.
  */
 const char *init_nsmap[][2] = {
     {"dc",       "http://purl.org/dc/elements/1.1/"},
     {"dcterms",  "http://purl.org/dc/terms/"},
     {"foaf",     "http://xmlns.com/foaf/0.1/"},
+    {"lsup",     LSUP_NS},
     {"rdf",      "http://www.w3.org/1999/02/22-rdf-syntax-ns#"},
     {"rdfs",     "http://www.w3.org/2000/01/rdf-schema#"},
     {"xsd",      "http://www.w3.org/2001/XMLSchema#"},

include/environment.h

@@ -1,46 +1,31 @@
 /** @file environment.h
  *
  * @brief Handle LSUP environment initialization and teardown.
+ *
+ * #LSUP_init() should be called before performing any other interaction with
+ * this library.
+ *
+ * #LSUP_done() is called automatically on program exit (`atexit`).
  */
 
 #ifndef _LSUP_ENVIRONMENT_H
 #define _LSUP_ENVIRONMENT_H
 
-#include "store_mdb.h"
 
+#include "term.h"
 
-/*
- * Data types.
- */
 
-/** @brief Environment structure containing "global" LSUP variables.
+/** @brief Whether the environment is already initialized.
  *
- * Multiple environments may be opened within one program. One environment,
- * the default one, must always be opened before performing any operation with
- * the library.
+ * @TODO Check if the default NS was inserted; this would be slower but more
+ * accurate.
  */
-typedef struct env_t {
-    LSUP_Buffer *       default_ctx;            // Default context URI.
-    LSUP_MDBStore *     mdb_store;              // MDB permanent store handle.
-    LSUP_MDBStore *     mdb_store_ramdisk;      // MDB RAM disk store handle.
-    LSUP_NSMap *        nsm;                    // Namespace prefix map.
-} LSUP_Env;
+#define LSUP_IS_INIT (LSUP_term_cache != NULL)
 
 
-/** @brief Environment variable that gets passed around.
- */
-extern LSUP_Env *LSUP_default_env;
-
-
-/** @brief Initialize default context and MDB environments.
- *
- * The ramdisk data will persist after the application is shut down, but they
- * will be wiped clean the next time this function is called.
- */
-LSUP_Env *
-LSUP_env_new (
-        const char *default_ctx, const char *mdb_path,
-        const LSUP_NSMap *nsmap);
+extern LSUP_NSMap *LSUP_default_nsm; /// Default namespace prefix map.
+extern LSUP_Term *LSUP_default_ctx; /// Default context.
+extern LSUP_Buffer *LSUP_default_ctx_buf; /// Serialized default context.
 
 
 /** @brief Initialize the default environment.
@@ -56,26 +41,24 @@ LSUP_env_new (
 LSUP_rc
 LSUP_init (void);
 
-
-/** @brief Close an environment.
- *
- * This only needs to be done for non-default environments. The environment
- * handle is not freed.
- */
-void
-LSUP_env_free (LSUP_Env *env);
-
-/** @brief Close the defailt environment.
+/** @brief Close the default environment.
  *
  * This is called by atexit(). If called before then, subsequent calls have
  * no effect.
  */
-void LSUP_done (void);
+void
+LSUP_done (void);
 
+
+/** TODO
+ */
 LSUP_rc
-LSUP_env_push_id (LSUP_Env *env, const uint32_t key, const char *data);
+LSUP_env_put_id (const uint32_t key, const char *data);
 
+
+/** TODO
+ */
 const char *
-LSUP_env_get_id (LSUP_Env *env, const uint32_t key);
+LSUP_env_get_id (const uint32_t key);
 
 #endif /* _LSUP_ENVIRONMENT_H */

include/graph.h

@@ -1,29 +1,14 @@
 #ifndef _LSUP_GRAPH_H
 #define _LSUP_GRAPH_H
 
+#include "store.h"
 #include "environment.h"
 #include "term.h"
 
-/*
- * Define backend types and checks.
- */
-
-#define BACKEND_TBL                                              \
-    ENTRY(  MEM,       0)/* Memory backend, hash map. */         \
-    ENTRY(  MDB,       1)/* LMDB back end on persistent disk. */ \
-    ENTRY(  MDB_TMP,   2)/* LMDB back end on RAM disk. */        \
-
-
-typedef enum LSUP_store_type {
-#define ENTRY(a, b) LSUP_STORE_##a = b,
-    BACKEND_TBL
-#undef ENTRY
-} LSUP_store_type;
-
 
 /** @brief Graph object.
  */
-typedef struct Graph LSUP_Graph;
+typedef struct graph_t LSUP_Graph;
 
 /** @brief Graph iterator.
  *
@@ -31,89 +16,49 @@ typedef struct Graph LSUP_Graph;
  * over lookup results with #LSUP_graph_iter_next. It must be freed with
  * #LSUP_graph_iter_free when done.
  */
-typedef struct GraphIterator LSUP_GraphIterator;
+typedef struct graph_iter_t LSUP_GraphIterator;
 
 
 /** @brief Create an empty graph.
  *
- * The new graph has zero capacity and a random URN. To change either one, use
- * #LSUP_graph_resize and #LSUP_graph_set_uri, respectively.
+ * @param[in] uri URI of the new graph. If NULL, a UUID4 URN is generated.
  *
- * The graph is assigned a default (volatile) namespace map if it's in memory,
- * hence all graphs share the same namespace map by default. To change this,
- * use #LSUP_graph_set_namespace(). MDB graphs use a persistent namespace map
- * that is common to all the graphs in the same store. This cannot be changed.
+ * @param store_type[in] Type of store backing the graph. One of the values of
+ *  #LSUP_StoreType.
  *
- * @param store_type[in] Type of store for the graph. One of the values of
- *  #LSUP_store_type.
+ * @param[in] store_id Identifier for the back end store. This may be
+ *  interpreted differently by each store implementation. For the MDB store,
+ *  this is the file path where the store is located. It is ignored by volatile
+ *  stores (with LSUP_STORE_PERM feature flag set to false). If a store
+ *  does not exist for the given identifier, a new one is initialized. If this
+ *  parameter is NULL, the default store for the selected type is used.
  *
- * @return LSUP_OK if the graph was created, or < 0 if an error occurred.
- */
-LSUP_Graph *
-LSUP_graph_new_env (
-        const LSUP_Env *env, LSUP_Term *uri, const LSUP_store_type store_type);
-
-
-/** @brief Create an empty graph with the default environment.
+ * @param[in] nsm Namespace map to use for an in-memory graph. This is ignored
+ *  by graphs backed by permanent stores, which handle their own namespace map.
+ *  If this is NULL, the graph is assigned a global namespace map that lives
+ *  until #LSUP_done() is called.
  *
- * This is likely to be used more often than #LSUP_graph_new_env().
- */
-#define LSUP_graph_new(uri, type) \
-    LSUP_graph_new_env (LSUP_default_env, uri, type)
-
-
-/** @brief Shortcut for #LSUP_graph_new_lookup_env() on default MDB store.
- */
-#define LSUP_graph_new_lookup(s, p, o) \
-    LSUP_graph_new_lookup_env (LSUP_default_env, (s), (p), (o))
-
-
-/** @brief copy a graph into a new one.
- *
- * The new graph is compacted to the minimum required size.
- *
- * src[in] Graph to be copied.
- *
- * @param uri URI of the destination graph. If NULL, a UUID4 URN is generated.
- *
- * @param gr[out] Pointer to a pointer to the destination graph. It must be
- *  freed with #LSUP_graph_free when done.
- *
- * @return LSUP_OK if the graph was copied, or < 0 if an error occurred.
+ * @return New graph, or NULL on error. Must be freed with #LSUP_graph_free().
  */
 LSUP_Graph *
-LSUP_graph_copy (const LSUP_Graph *src);
+LSUP_graph_new (
+        LSUP_Term *uri, const LSUP_StoreType store_type, const char *store_id,
+        LSUP_NSMap *nsm, size_t size);
 
 
-/** @brief Copy the contents of a graph into a permanent store.
- *
- * It is possible to store a memory graph, a RAMdisk MDB graph, or a
- * permanently stored graph into another environment.
- *
- * The namespace map associated with the graph is stored into the destination
- * as well, except for existing namespaces and prefixes.
+/** @brief Copy triples from a source graph into a destination one.
  *
- * @param[in] src Graph to store.
- *
- * @param[out] dest Pointer to graph handle for the new stored graph. The new
- *  graph will have the same URI as the source. It may be NULL.
- *
- * @param[in] env Environment to copy to. If NULL, it is set to the deafult
- *  LSUP store. This makes it possible to copy MDB graphs across different
- *  environments. If the source is a MDB graph and the environment is the same
- *  as the source, no change occurs.
- *
- * @return LSUP_OK on success; LSUP_NOACTION if the graph is already stored in
- *  the same enviroment; <0 on error.
+ * The destination graph is not initialized here, so the copy is cumulative.
  */
 LSUP_rc
-LSUP_graph_store (
-        const LSUP_Graph *src, LSUP_Graph **dest_p, const LSUP_Env *env);
+LSUP_graph_copy_contents (const LSUP_Graph *src, LSUP_Graph *dest);
 
 
 /** Perform a boolean operation between two graphs.
  *
- * This method yields a new graph as the result of the operation.
+ * This method populates an initialized graph with the result of the operation
+ * between two other graphs. The resulting graph may be of any store type and
+ * may be the result of graphs of different store types.
  *
  * @param op[in] Operation to perform. One of #LSUP_bool_op.
  *
@@ -121,12 +66,16 @@ LSUP_graph_store (
  *
  * @param gr2[in] Second operand.
  *
- * @param res[out] Result graph. It must be freed with #LSUP_graph_free when
- *  done.
+ * @param res[out] Result graph. The handle should be initialized via
+ *  #LSUP_graph_new() or equivalent. Any preexisting contents are not removed.
+ *  If an unrecoverable error occurs, this graph is freed.
+ *
+ * @return LSUP_OK on success; <0 on error.
  */
-LSUP_Graph *
+LSUP_rc
 LSUP_graph_bool_op(
-        const LSUP_bool_op op, const LSUP_Graph *gr1, const LSUP_Graph *gr2);
+        const LSUP_bool_op op, const LSUP_Graph *gr1, const LSUP_Graph *gr2,
+        LSUP_Graph *res);
 
 
 /** @brief Free a graph.

include/namespace.h

@@ -9,10 +9,6 @@
  */
 #define PFX_LEN 8
 
-/** @brief Default namespace. Only available upon environment initialization.
- */
-#define LSUP_DEF_NSM LSUP_default_env->nsm
-
 
 /** @brief Namespace map structure.
  *

include/store.h

@@ -1,29 +1,70 @@
 /** @file store.h
  *
- * @brief Common back end store definitions.
+ * @brief Generic store dependency.
  *
- * New store implementations should include this header.
+ * This code allows to use the store interface with any supported back end
+ * without any knowledge of the back end implementations. Code using the store
+ * interface need only include this file.
+ *
+ * New store implementations should be added to this file as `#include`s as
+ * well as entries in the `BACKEND_TBL` macro.
  */
 
-
 #ifndef _LSUP_STORE_H
 #define _LSUP_STORE_H
 
+/*
+ * Add new back end headers here.
+ */
+#include "store_htable.h"
+#include "store_mdb.h"
+
 
 /*
- * Store feature flags.
+ * Define backend types.
+ *
+ * Add new store implementations to this table.
+ */
+#define BACKEND_TBL                                                           \
+/*          #enum pfx   #store if       */\
+    ENTRY(  HTABLE,     htstore_int  )  \
+    ENTRY(  MDB,        mdbstore_int ) \
+
+
+/** @brief Store types. All prefixed with `LSUP_STORE_`.
+ */
+typedef enum {
+#define ENTRY(a, b) \
+    LSUP_STORE_##a,
+BACKEND_TBL
+#undef ENTRY
+} LSUP_StoreType;
+
+
+/** @brief Return store interface for a specific type.
+ */
+const LSUP_StoreInt *LSUP_store_int (LSUP_StoreType type);
+
+
+/** @brief Store structure.
+ *
+ * Code using the store interface should create an instance of this structure
+ * with pointers to the store interface of their choice, and to an opaque
+ * structure to hold the store state.
+ *
+ * Iterator state handles generated by lookup and add functions are kept
+ * outside of this structure, but manipulated by the interface specified in
+ * here.
  *
- * NOTE: LSUP_STORE_PERM need only be set by an implementation based on whether
- * its path is on a default temporary dir (e.g. LSUP_MDB_RAMDISK_PATH). If this
- * flag is not set, it means the data will be cleared before the next execution
- * of the program. However, its being set does not guarantee the persistence of
- * the medium (i.e. a "permanent" store may have been created ad hoc on a
- * tempfs).
+ * @sa #LSUP_graph_new()
  */
-#define LSUP_STORE_PERM     1<<0    /// Store is on a permanent location.
-#define LSUP_STORE_CTX      1<<1    /// Store supports contexts (quads).
-#define LSUP_STORE_IDX      1<<2    /// Store is fully SPO(C)-indexed.
-#define LSUP_STORE_TXN      1<<3    /// Supports manual transaction handling.
-#define LSUP_STORE_NET      1<<4    /// Store is over a network protocol.
+typedef struct store_it {
+    LSUP_StoreType                  type;   ///< Store type.
+    char *                          id;     /**< Store ID. NOTE: This is
+                                             *   NULL for volatile stores.
+                                             */
+    const LSUP_StoreInt *           sif;    ///< Store interface.
+    void *                          data;   ///< Store back end data.
+} LSUP_Store;
 
-#endif  /* _LSUP_STORE_H */
+#endif  /* LSUP_STORE_H */

include/store_base.h

@@ -0,0 +1,438 @@
+/** @file store.h
+ *
+ * @brief Common store back end interfaces.
+ *
+ * Code using the store interface should include NOT this header, but rahter
+ * `store.h`.
+ *
+ * This header is included by all back end implementations, which are in
+ * their turn included by `store.h`.
+ *
+ * The basic interfaces for store and store iterator implementations are
+ * defined here. New store implementations should include this header and
+ * implement three basic elements:
+ *
+ * - A structure representing the store back end. This structure will be
+ *   opaque to all downstream code and its layout is entirely up to the
+ *   implementer.
+ *
+ * - A structure representing a store iterator state, also opaque.
+ *
+ * - The LSUP_StoreInt interface with all the functions defined in the
+ *   interface necessary to interact with the store.
+ *
+ * See the `store_htable.{c,h}` and `store_mdb.{c,h}` files for examples of
+ * fully functioning implementations.
+ *
+ * The #LSUP_StoreInt structure defines a store interface for raw buffer
+ * triples. Nothing in the store functions' signatures should hint at RDF
+ * triples—they should accept and produce exclusively raw byte buffers
+ * (#LSUP_Buffer). A store interface may have any of the `LSUP_STORE_*` faeture
+ * flags which should be reflected in the way its members are implemented.
+ */
+
+
+#ifndef _LSUP_STORE_BASE_H
+#define _LSUP_STORE_BASE_H
+
+#include "environment.h"
+
+/*
+ * Store feature flags.
+ *
+ * NOTE: LSUP_STORE_PERM need only be set by an implementation based on whether
+ * its path is on a default temporary dir (e.g. LSUP_MDB_RAMDISK_PATH). If this
+ * flag is not set, it means the data will be cleared before the next execution
+ * of the program. However, its being set does not guarantee the persistence of
+ * the medium (i.e. a "permanent" store may have been created ad hoc on a
+ * tempfs).
+ */
+typedef enum {
+    LSUP_STORE_PERM     = 1<<0,   ///< Store is on a permanent support.
+    LSUP_STORE_CTX      = 1<<1,   ///< Store supports contexts (quads).
+    LSUP_STORE_IDX      = 1<<2,   ///< Store is fully SPO(C)-indexed.
+    LSUP_STORE_TXN      = 1<<3,   ///< Supports transaction handling.
+    LSUP_STORE_COW      = 1<<4,   ///< Copy on write. @sa #iter_next_fn_t()
+    //LSUP_STORE_NET      = 1<<5,   ///< Store is over a network protocol.
+} LSUP_StoreFeature;
+
+
+/*
+ * Store function types.
+ */
+
+/** @brief Prototype: create any environment necessary for the store to work.
+ *
+ * This function should be idempotent on separate calls to the same `id`,
+ * unless the `clear` option is set to `true`.
+ *
+ * @param[in,out] id Identifier to use for the store. This should be
+ * a URI that uniquely identifies a back end for the implementation using it,
+ * e.g. a SQL connection string, file path for an embedded store, the URL of a
+ * REST API endpoint, etc. It may also be NULL, in which case it will be set to
+ * the default identifier set by the implementation. It can be retrieved from
+ * an existing store via #store_id_fn_t .
+ *
+ * @param[in] clear Whether to remove an existing environment with the same ID.
+ */
+typedef LSUP_rc (*store_setup_fn_t)(const char *id, bool clear);
+
+
+/** @brief Prototype: create a new store.
+ *
+ * @param[in] id Identifier for the new store. How this is interpreted, and
+ * whether it is even used, depends on the implementation, which should
+ * provide documentation on how to pass and interpret this parameter.
+ *
+ * @param[in] size Initial size for the store. It may be 0. Only meaningful
+ *  for stores that may preallocate memory, such as #HTStore.
+ *
+ * @return New store handle.
+ */
+typedef void * (*store_new_fn_t)(const char *id, size_t size);
+
+
+/** @brief Prototype: free store handle.
+ *
+ * @param[in] store Store handle.
+ *
+ */
+typedef void (*store_free_fn_t)(void *store);
+
+
+/** @brief Prototype: get the store ID.
+ *
+ * @param store[in] Store handle.
+ *
+ * @return store ID string. This is a copy and should be freed after use.
+ */
+typedef char * (*store_id_fn_t)(const void *store);
+
+
+/** @brief Prototype: get store size.
+ *
+ * @param store[in] The store to calculate size of.
+ *
+ * @return Number of stored SPO triples (across all contexts if supported).
+ */
+typedef size_t (*store_size_fn_t)(const void *store);
+
+
+/** @brief Print stats about a store.
+ *
+ * TODO
+ *
+ * @param store[in] The store to get stats for.
+ */
+/* TODO
+typedef LSUP_rc (*store_stat_fn_t)(void *store, void *stat);
+*/
+
+
+/** @brief Initialize bulk triple load.
+ *
+ * This is the first step of a bulk load. It is best used when the data at hand
+ * need to be pre-processed, which can be done in the same loop as the next
+ * step to keep memory usage low.
+ *
+ * @param store[in] The store to add to.
+ *
+ * @param sc[in] Context as a serialized term. If this is NULL, and the
+ *  default context is not NULL, triples will be added to the default context
+ *  for the store, If the default context for the store is NULL, regardless of
+ *  the value of sc, triples will be added with no context. Only meaningful
+ *  for stores with the LSUP_STORE_CTX feature.
+ *
+ * @return Iterator handle to be passed to the following load steps.
+ */
+typedef void * (*store_add_init_fn_t)(void *store, const LSUP_Buffer * sc);
+
+
+/** @brief Add one triple into the store.
+ *
+ * This must be called after #add_init_fn, using the iterator
+ * yielded by that function. It may be called multiple times and must be
+ * followed by #add_done_fn or #add_abort_fn (if supported).
+ *
+ * @param it[in] Iterator obtained by #LSUP_mdbstore_add_init.
+ *  The following members are of interest:
+ *  it->i stores the total number of records inserted.
+ *
+ * @param sspo[in] Serialized triple to be added.
+ *
+ * @return LSUP_OK if the triple was inserted; LSUP_NOACTION if the triple
+ *  already existed; LSUP_DB_ERR if an MDB error occurred.
+ */
+typedef LSUP_rc (*store_add_iter_fn_t)(
+        void *it, const LSUP_BufferTriple * sspo);
+
+
+/** @brief Abort an add loop and free iterator.
+ *
+ * Usually called on an irrecoverable error from #add_iter_fn. None of the
+ * successful inserts in the same loop is retained.
+ *
+ * @param it[in] Iterator obtained by #LSUP_mdbstore_add_init.
+ */
+typedef void (*store_add_abort_fn_t)(void *it);
+
+
+/** @brief Finalize an add loop and free iterator.
+ *
+ * This must be called after #add_iter_fn.
+ *
+ * @param it[in] Iterator obtained by #LSUP_mdbstore_add_init.
+ */
+typedef LSUP_rc (*store_add_done_fn_t)(void *it);
+
+
+/** @brief Add a single term to the store.
+ *
+ * @param[in] store Store handle.
+ *
+ * @param[in] sterm Serialized term to store.
+ */
+typedef LSUP_rc (*store_add_term_fn_t)(void *store, const LSUP_Buffer *sterm);
+
+
+/** @brief Prototype: look up triples by pattern matching.
+ *
+ * This function may return a count of matches and/or an iterator of results as
+ * serialized triples.
+ *
+ * Any and all of the terms may be NULL, which indicates an unbound query
+ * term. Stores with context not set or witout context support will always
+ * ignore the fourth term.
+ *
+ * @param[in] store The store to be queried.
+ *
+ * @param[in] ss Buffer representing the serialized s term.
+ *
+ * @param[in] sp Buffer representing the serialized p term.
+ *
+ * @param[in] so Buffer representing the serialized o term.
+ *
+ * @param[in] sc Serialized context to limit search to. It may be NULL, in
+ * which case search is done in all contexts. Note that triples inserted
+ * without context are assigned the *default* context for the store.
+ *
+ * @param[out] ct If not NULL, this will be populated with the number of
+ *  entries found. It is very inexpensive to set for lookups without context,
+ *  much less so for 1-bound and 2-bound context lookups, in which cases it
+ *  should be set only if needed.
+ *
+ * @return Iterator handle that will be populated with a result iterator. This
+ * is always created even if no matches are found and must be freed with
+ * #LSUP_mdbiter_free() after use. If matches are found, the iterator points to
+ * the first result which can be retrieved with #iter_next_fn().
+ */
+typedef void * (*store_lookup_fn_t)(
+        void *store,
+        const LSUP_Buffer *ss, const LSUP_Buffer *sp, const LSUP_Buffer *so,
+        const LSUP_Buffer *sc, size_t *ct);
+
+
+/** @brief Prototype: check for existence of a triple (T/F).
+ *
+ * @param[in] Store to be queried.
+ *
+ * @param[in] spo Triple to look up. All members must not be NULL.
+ *
+ * @param[in] c Optional context to look into. It may be NULL. It is
+ *  disregarded by stores without the LSUP_STORE_CTX feature.
+ *
+ * @return Whether the triple exist in the store (/context).
+ */
+typedef bool (*store_trp_exist_fn_t)(
+        void *store, const LSUP_BufferTriple *sspo, const LSUP_Buffer *sc);
+
+
+/** @brief Prototype: delete triples by pattern matching.
+ *
+ * The ss, sp, so, sc terms act as a matching pattern as documented in
+ * #store_lookup_fn. if not NULL, ct yields the number of triples actually
+ * deleted.
+ */
+typedef LSUP_rc (*store_remove_fn_t)(
+        void *store,
+        const LSUP_Buffer *ss, const LSUP_Buffer *sp, const LSUP_Buffer *so,
+        const LSUP_Buffer *sc, size_t *ct);
+
+
+/** @brief Put an in-memory namespace map into a permanent back end.
+ *
+ * This is only available in stores with the LSUP_STORE_PERM feature.
+ *
+ * Existing prefixes and namespaces are not updated. Thus, if the following are
+ * already stored:
+ *
+ * ns1: <urn:ns:a#>
+ * ns2: <urn:ns:b#>
+ *
+ * Neither of the following will be inserted:
+ *
+ * ns3: <urn:ns:a#>
+ * ns2: <urn:ns:c#>
+ *
+ * @param[in] store MDB store to update.
+ *
+ * @param[out] nsm Namespace map handle to store.
+ *
+ * @return LSUP_OK if all terms were updated; LSUP_CONFLICT if one or more
+ *  namespaces or terms were not updated because they already existed; <0 if
+ *  an error occurred.
+ */
+typedef LSUP_rc (*store_nsm_put_fn_t)(void *store, const LSUP_NSMap * nsm);
+
+
+/** @brief Get the store's namespace prefix map.
+ *
+ * @param[in] store MDB store to query.
+ *
+ * @return NS map or NULL on error.
+ */
+typedef LSUP_NSMap * (*store_nsm_get_fn_t)(void *store);
+
+
+/*
+ * Iterator function types.
+ */
+
+/** @brief Prototype: yield the matching triples and advance the iterator.
+ *
+ * NOTE: Iterators keep transactions open. Don't hold on to them longer than
+ * necessary.
+ *
+ * NOTE: If the store interface has the LSUP_STORE_COW feature, the memory
+ * buffer referenced by the #LSUP_Buffer handle is owned by the database. It
+ * must not be written to or freed. To modify the data or use them beyond the
+ * caller's scope, this memory must be copied. Note that the #LSUP_Buffer
+ * handle must still be freed (with a plain `free()`), but not the underlying
+ * data buffer, since only the latter is owned by the back end. For stores
+ * without the LSUP_STORE_COW, data are copied on retrieval and the resulting
+ * buffers can be freed with #LSUP_buffer_free() or analogous methods.
+ *
+ * @param[in] it Opaque iterator handle obtained with the store's #lookup_fn.
+ *
+ * @param[out] sspo #LSUP_BufferTriple to be populated with three serialized
+ * terms if found. It may be NULL. NOTE: the content of this variable is
+ * undefined on rc != LSUP_OK.
+ *
+ * @param[out] ctx If not NULL, it is populated with a NULL-terminated array of
+ *  LSUP_Buffer structs, one for each context associated with the matching
+ *  triple. These contexts are the same regardless of the context filter used
+ *  in the lookup. The array is freed with a simple #free(). This parameter
+ *  is ignored by implementations without the LSUP_STORE_CTX feature.
+ *
+ *  To iterate over the context array, use this loop:
+ *
+ *      size_t i = 0;
+ *      while (ctx[i].addr)
+ *          do_something(ctx + (i++));
+ *
+ * @return LSUP_OK if results were found; LSUP_END if no (more) results were
+ * found; LSUP_DB_ERR if a backend error occurred.
+ */
+typedef LSUP_rc (*iter_next_fn_t)(
+        void *it, LSUP_BufferTriple *sspo, LSUP_Buffer **ctx);
+
+
+/** @brief Prototype: free an iterator allocated by a lookup.
+ *
+ * @param it[in] Iterator pointer. It will be set to NULL after freeing.
+ */
+typedef void (*iter_free_fn_t)(void * it);
+
+
+/*
+ * Iterface type definitions.
+ */
+
+/** @brief Store interface.
+ */
+typedef struct store_if_t {
+    // Basic properties.
+    char                name[16];       ///< Store type name.
+    LSUP_StoreFeature   features;       ///< Feature flags.
+
+    // Allocation, setup and deallocation.
+    store_setup_fn_t    setup_fn;       ///< Called before #store_new_fn_t.
+    store_new_fn_t      new_fn;         ///< Create a new store instance.
+    store_free_fn_t     free_fn;        ///< Free the store.
+
+    // Metadata.
+    store_size_fn_t     size_fn;        ///< Number of triples in the store.
+    store_id_fn_t       id_fn;          ///< Get store ID.
+
+    // Addition.
+    store_add_init_fn_t add_init_fn;    ///< Initialize add iteration.
+    store_add_iter_fn_t add_iter_fn;    ///< Add one triple.
+    store_add_abort_fn_t add_abort_fn;  /**< Abort (roll back) the add
+                                         *  process.  Only available in
+                                         *  stores with #LSUP_STORE_TXN
+                                         *  feature. Optional.
+                                         */
+    store_add_done_fn_t add_done_fn;    ///< Complete the add process.
+    store_add_term_fn_t add_term_fn;    /**< Add (index) a term to the store.
+                                         *  Only available in stores with
+                                         *  #LSUP_STORE_IDX feature. Optional.
+                                         */
+
+    // Look up.
+    store_lookup_fn_t   lookup_fn;      ///< Look up triples by pattern. 
+    //store_trp_exist_fn_t exist_fn;      ///< Check if a triple exists.
+    iter_next_fn_t      lu_next_fn;     ///< Advance the lookup iterator.
+    iter_free_fn_t      lu_free_fn;     ///< Free the lookup iterator.
+
+    // Removal.
+    store_remove_fn_t   remove_fn;      ///< Remove triples by pattern.
+
+    // Namespace prefix mapping.
+    store_nsm_put_fn_t  nsm_put_fn;     /**< Add a namespace/prefix pair to
+                                         *  the prefix map.
+                                         *  Only available (and mandatory)
+                                         *  in stores with the
+                                         *  #LSUP_STORE_IDX feature.
+                                         */
+    store_nsm_get_fn_t  nsm_get_fn;     /**< Get a namespace/prefix from
+                                         *  the prefix map.
+                                         *  Only available (and mandatory)
+                                         *  in stores with the
+                                         *  #LSUP_STORE_IDX feature.
+                                         */
+} LSUP_StoreInt;
+
+
+/*
+ * Template for a new store and iterator implementation.
+ * These should be placed in the .c file where the interface functions are
+ * defined, and declared as `extern` in the related .h file.
+
+const LSUP_StoreInt my_store_int = {
+    .name           = "My Store", // Truncated to 15 chars.
+    .features       = LSUP_STORE_PERM | LSUP_STORE_IDX,
+
+    .setup_fn       = my_setup_fn,
+    .new_fn         = my_new_fn,
+    .free_fn        = my_free_fn,
+
+    .size_fn        = my_size_fn,
+
+    .add_init_fn    = my_init_fn,
+    .add_iter_fn    = my_iter_fn,
+    .add_abort_fn   = my_add_abort_fn,
+    .add_done_fn    = my_add_done_fn,
+    .add_term_fn    = my_add_term_fn,
+
+    .lookup_fn      = my_lookup_fn,
+    .lu_next_fn     = my_iter_next_fn,
+    .lu_free_fn     = my_iter_free_fn,
+
+    .remove_fn      = my_remove_fn,
+
+    .nsm_put_fn     = my_nsm_put_fn,
+    .nsm_get_fn     = my_nsm_get_fn,
+};
+*/
+
+#endif  /* _LSUP_STORE_BASE_H */

include/store_htable.h

@@ -1,4 +1,4 @@
-/** @file store.htable.h
+/** @file store_htable.h
  *
  * @brief Simple in-memory triple store back end based on hash tables.
  *
@@ -21,198 +21,9 @@
 #define _LSUP_STORE_HTABLE_H
 
 #include "buffer.h"
-#include "store.h"
+#include "store_base.h"
 
 
-typedef struct ht_store_t LSUP_HTStore;
-typedef struct ht_iterator_t LSUP_HTIterator;
-
-LSUP_HTStore *
-LSUP_htstore_new (const size_t size);
-
-
-/** @brief Boolean operation on hash table triples.
- *
- * The resulting store is compacted to the minimum size necessary to hold all
- * results.
- *
- * @param[in] op Operation type. See #LSUP_bool_op
- *
- * @param[in] s1 First store.
- *
- * @param[in] s2 Second store.
- *
- * @return New store resulting from the operation. It must be freed with
- * #LSUP_htstore_free after use.
- */
-LSUP_HTStore *
-LSUP_htstore_bool_op (
-        const LSUP_bool_op op, const LSUP_HTStore *s1, const LSUP_HTStore *s2);
-
-
-/** @brief Free a hash table store.
- */
-void
-LSUP_htstore_free (LSUP_HTStore *ht);
-
-
-/** @brief Duplicate a store.
- *
- * @param[in] src Store to duplicate.
- *
- * @return New store. It must be freed with #LSUP_htstore_free() after use.
- */
-LSUP_HTStore *
-LSUP_htstore_copy (const LSUP_HTStore *src);
-
-
-/** @brief Copy contents of a store to another store.
- *
- * The destination is not initialized, so copy is cumulative with the existing
- * content.
- *
- * @param[in] Store to copy to. It must be already initialized via
- *  #LSUP_htstore_new(), #LSUP_htstore_copy(), etc.
- *
- * @param[in] src Store to copy from.
- */
-LSUP_rc
-LSUP_htstore_copy_contents (LSUP_HTStore *dest, const LSUP_HTStore *src);
-
-/** @brief Count triples in a store.
- *
- * @parm[in] store HTStore handle.
- *
- * @return Number of triples in the store.
- */
-size_t
-LSUP_htstore_size (const LSUP_HTStore *ht);
-
-
-/** @brief Add a term to the store.
- *
- * @parm[in] store HTStore handle.
- *
- * @param[in] sterm Serialized term to insert. The term is copied and may be
- *  safely freed after the operation.
- *
- * @return LSUP_OK on success; LSUP_NOACTION if the term exists already; <0
- *  on error.
- */
-LSUP_rc
-LSUP_htstore_add_term (LSUP_HTStore *store, const LSUP_Buffer *sterm);
-
-
-/** @brief Initialize a loop to add triples to a store.
- *
- * @param[in] store Store handler.
- *
- * @return Iterator to be used with #LSUP_htstore_add_iter(). It must be freed
- *  with #LSUP_htstore_add_done().
- */
-LSUP_HTIterator *
-LSUP_htstore_add_init (LSUP_HTStore *store);
-
-
-/** @brief Add triples to the store.
- *
- * @param[in] it Iterator handle created with #LSUP_htstore_add_init().
- *
- * @param[in] sspo Serialized buffer triple to add.
- */
-LSUP_rc
-LSUP_htstore_add_iter (LSUP_HTIterator *it, const LSUP_BufferTriple *sspo);
-
-
-/** @brief Free resources related to an add loop.
- *
- * @param[in] it Iterator to free.
- */
-void
-LSUP_htstore_add_done (LSUP_HTIterator *it);
-
-/** @brief Find triples by pattern matching and return an iterator.
- *
- * The iterator may yield results by using #LSUP_htiter_next() and must be
- * freed with #LSUP_htiter_free().
- *
- * @param[in] store Store to search in.
- *
- * @param[in] ss Serialized subject term. If NULL, the term is unbound.
- *
- * @param[in] sp Serialized predicate term. If NULL, the term is unbound.
- *
- * @param[in] so Serialized object term. If NULL, the term is unbound.
- *
- * @param[out] ct If not NULL, it is populated with the number of results. Use
- *  only if necessary: since the hash table is not indexed, retrieving the
- *  count requires looping over the results, thus slowing down the operation.
- *
- * @return Iterator for lookup results.
- */
-LSUP_HTIterator *
-LSUP_htstore_lookup (
-        LSUP_HTStore *store, const LSUP_Buffer *ss, const LSUP_Buffer *sp,
-        const LSUP_Buffer *so, size_t *ct);
-
-
-/** @brief Find the next triple in a lookup and return the result.
- *
- * @param[in] it Iterator obtained from #LSUP_htstore_lookup().
- *
- * @param[out] spo Serialized triple pointer to be populated with the result,
- *  if found.
- *
- * @return LSUP_OK if a result was found; LSUP_END if the end of the iterator
- *  is reached.
- */
-LSUP_rc
-LSUP_htiter_next (LSUP_HTIterator *it, LSUP_BufferTriple *sspo);
-
-
-/** @brief Count of lookup results or triples added in an iteration.
- *
- * @param[in] it Iterator handle.
- *
- * @return Number of results yielded, or triples added, at a certain point of
- *  an iterator.
- */
-/*
-size_t
-LSUP_htiter_count (const LSUP_HTIterator *it);
-*/
-
-
-/** @brief Free an iterator.
- *
- * @param[in] it Iterator handle obtained from #LSUP_htstore_lookup().
- */
-void
-LSUP_htiter_free (LSUP_HTIterator *it);
-
-
-/** @brief Remove triples by pattern matching.
- *
- * The search criteria are the same used for #LSUP_htstore_lookup().
- *
- * @param[in] store Store to remove triples from.
- *
- * @param[in] ss Serialized subject term. If NULL, the term is unbound.
- *
- * @param[in] sp Serialized predicate term. If NULL, the term is unbound.
- *
- * @param[in] so Serialized object term. If NULL, the term is unbound.
- *
- * @param[out] Optional pointer to a counter. If not NULL, it is populated with
- *      the number of triples removed. It is undefined if LSUP_DB_ERR is
- *      returned.
- *
- * @return LSUP_OK if any triples were deleted; LSUP_NOACTION if no triples
- *      were found for deletion; <0 on error.
- */
-LSUP_rc
-LSUP_htstore_remove (
-        LSUP_HTStore *store, const LSUP_Buffer *ss, const LSUP_Buffer *sp,
-        const LSUP_Buffer *so, size_t *ct);
+extern const LSUP_StoreInt htstore_int;
 
 #endif  // _LSUP_STORE_HTABLE_H

include/store_mdb.h

@@ -25,349 +25,13 @@
 #include "lmdb.h"
 
 #include "buffer.h"
-#include "namespace.h"
-#include "store.h"
+#include "store_base.h"
 
 
 // FIXME find a better cross-platform path.
-#define DEFAULT_ENV_PATH "./mdb_store"
-
-// RAMdisk path for MDB volatile store.
-#define LSUP_MDB_RAMDISK_PATH TMPDIR "/lsup_mem_graph"
-
-
-typedef char DbLabel[8];
-typedef struct mdbstore_t LSUP_MDBStore;
-typedef struct mdbstore_iter_t LSUP_MDBIterator;
-
-typedef LSUP_rc (*store_match_fn_t)(const LSUP_TripleKey spok, void *data);
-
-// TODO Introduce compile-time LSUP_BIG_STORE option to define two store
-// options: false: 64-bit hashes, uint32 keys, max 4G entries; true:
-// 128-bit hashes, size_t keys, max MAX_SIZE entries, larger and slower.
-// Ideally this could be specified at runtime to handle different stores with
-// different sizes, but code could become more complex.
-
-
-/** @brief Create the MDB environment and databases on disk.
- *
- * This function takes care of creaating the environment path if not existing,
- * and checking that it's a writable directory. If the path is not specified
- * in the LSUP_STORE_PATH environment variable, a default directory is used.
- *
- * @param[in] clear Whether to remove a previous environment at this location.
- *
- * @param[in,out] path Path of the suggested directory to use. It may be NULL,
- *  in which case it will be set either to the environment variable
- *  LSUP_STORE_PATH, or if that is not set, a default local path.
- */
-LSUP_rc LSUP_mdbstore_setup (const char *path, bool clear);
-
-
-/** @brief Open an MDB store.
- *
- * The store must have been set up with #LSUP_mdbstore_setup.
- *
- * Some environment variables affect various store parameters:
- *
- * - LSUP_MDB_MAPSIZE Long int specifying the size of the memory map. Usually
- *   it is not necessary to modify this, unless one is operating under memory
- *   and disk constraints. The default map size is 1Tb.
- *
- * @param[in,out] store Uninitialized store struct pointer.
- *
- * @param[in] path MDB environment path. This must be the path given by
- * #LSUP_mdbstore_setup.
- *
- * @param[in] default_ctx Serialized URI to be used as a default context for
- *  triples inserted without a context specified. If NULL, the store operates
- *  in triple mode.
- */
-LSUP_MDBStore *
-LSUP_mdbstore_new (const char *path, const LSUP_Buffer *default_ctx);
-
-
-/** @brief Close a store and free its handle.
- *
- * @param[in] store Store pointer.
- *
- */
-void LSUP_mdbstore_free (LSUP_MDBStore *store);
-
-
-/** @brief Store feature flags.
- *
- * @param[in] store Store handle.
- *
- * @return A combination of LSUP_STORE_* feature flags.
- */
-int LSUP_mdbstore_features (LSUP_MDBStore *store);
-
-
-/** @brief Print stats about a store and its databases.
- *
- * TODO
- *
- * @param store[in] The store to get stats for.
- */
-LSUP_rc LSUP_mdbstore_stat (LSUP_MDBStore *store, MDB_stat *stat);
-
-
-/** @brief Store size.
- *
- * @param store[in] The store to calculate size of.
- *
- * @return Number of stored SPO triples across all contexts.
- */
-size_t LSUP_mdbstore_size (LSUP_MDBStore *store);
-
-
-/** @brief Initialize bulk triple load.
- *
- * This is the first step of a bulk load. It is best used when the data at hand
- * need to be pre-processed, which can be done in the same loop as the next
- * step to keep memory usage low.
- *
- * @param store[in] The store to add to.
- *
- * @param sc[in] Context as a serialized term. If this is NULL, and the
- *  default context is not NULL, triples will be added to the default context
- *  for the store, If the default context for the store is NULL, regardless of
- *  the value of sc, triples will be added with no context.
- *
- * @param it[out] Pointer to an iterator pointer to be passed to the following
- *  load steps.
- */
-LSUP_MDBIterator *
-LSUP_mdbstore_add_init (LSUP_MDBStore *store, const LSUP_Buffer *sc);
-
-
-/** @brief Add one triple into the store.
- *
- * This must be called after #LSUP_mdbstore_add_init, using the iterator
- * yielded by that function. It may be called multiple times and must be
- * followed by #LSUP_mdbstore_add_done.
- *
- * NOTE: at the moment #LSUP_mdbstore_remove() or another
- * #LSUP_mdbstore_init() cannot be called between #LSUP_mdbstore_add_init and
- * #LSUP_mdbstore_add_abort or #LSUP_mdbstore_add_done. FIXME
- *
- * @param it[in] Iterator obtained by #LSUP_mdbstore_add_init.
- *  The following members are of interest:
- *  it->i stores the total number of records inserted.
- *
- * @param sspo[in] Serialized triple to be added.
- *
- * @return LSUP_OK if the triple was inserted; LSUP_NOACTION if the triple
- *  already existed; LSUP_DB_ERR if an MDB error occurred.
- */
-LSUP_rc
-LSUP_mdbstore_add_iter (LSUP_MDBIterator *it, const LSUP_BufferTriple *sspo);
-
-
-/** @brief Finalize an add loop and free iterator.
- *
- * If a count of inserted records is needed, #LSUP_mdbiter_cur must be called
- * before this function.
- *
- * This must be called after #LSUP_mdbstore_add_iter.
- *
- * @param it[in] Iterator obtained by #LSUP_mdbstore_add_init.
- */
-LSUP_rc
-LSUP_mdbstore_add_done (LSUP_MDBIterator *it);
-
-
-/** @brief Abort an add loop and free iterator.
- *
- * Usually called on an irrecoverable error from LSUP_mdb_add_iter. None of the
- * successful inserts in the same loop is retained.
- *
- * @param it[in] Iterator obtained by #LSUP_mdbstore_add_init.
- */
-void
-LSUP_mdbstore_add_abort (LSUP_MDBIterator *it);
-
-
-/** @brief Add a batch of triples with optional context to the store.
- *
- * This is a shortcut for calling #LSUP_mdbstore_add_init,
- * #LSUP_mdbstore_add_iter and #LSUP_mdbstore_add_done in a sequence
- * when an array of pre-serialized triples is available.
- *
- * @param store[in] The store to add to.
- *
- * @param sc[in] Context as a serialized term. If this is NULL, and the
- *  default context is not NULL, triples will be added to the default context
- *  for the store. If the default context for the store is NULL, regardless of
- *  the value of sc, triples will be added with no context.
-
- * @param data[in] Triples to be inserted as a 2D array of triples in the shape
- * of data[n][3], where n is the value of data_size.
- *
- * @param inserted[out] If not NULL, it will be filled with the count of
- *  effectively inserted triples.
- *
- * @param data_size[in] Number of triples to be inserted.
- */
-LSUP_rc LSUP_mdbstore_add(
-        LSUP_MDBStore *store, const LSUP_Buffer *sc,
-        const LSUP_BufferTriple strp[], const size_t ct, size_t *inserted);
-
-
-/** @brief Delete triples by pattern matching.
- *
- * The ss, sp, so, sc terms act as a matching pattern as documented in
- * #LSUP_mdbstore_lookup. if not NULL, ct yields the number of triples actually
- * deleted.
- */
-LSUP_rc
-LSUP_mdbstore_remove(
-        LSUP_MDBStore *store, const LSUP_Buffer *ss, const LSUP_Buffer *sp,
-        const LSUP_Buffer *so, const LSUP_Buffer *sc, size_t *ct);
-
-
-/** @brief Look up matching triples and optional context.
- *
- * This function may return a count of matches and/or an iterator of results as
- * serialized triples.
- *
- * Any and all of the terms may be NULL, which indicates an unbound query
- * term. Stores with context not set will always ignore the fourth term.
- *
- * @param[in] store The store to be queried.
- *
- * @param[in] ss Buffer representing the serialized s term.
- *
- * @param[in] sp Buffer representing the serialized p term.
- *
- * @param[in] so Buffer representing the serialized o term.
- *
- * @param[in] sc Serialized context to limit search to. It may be NULL, in which
- *  case search is done in all contexts. Note that triples inserted without
- *  context are assigned the *default* context, indicated by the "default_ctx"
- *  member of the store struct.
- *
- * @param[out] it Pointer to an #LSUP_MDBIterator handle that will be populated
- * with a result iterator. This is always created even if no matches are found
- * and must be freed with #LSUP_mdbiter_free() after use. If matches are found,
- * the iterator points to the first result which can be retrieved with
- * #LSUP_mdbiter_next().
- *
- * @param[out] ct If not NULL, this will be populated with the number of
- *  entries found. It is very inexpensive to set for lookups without context,
- *  much less so for 1-bound and 2-bound context lookups, in which cases it
- *  should be set only if needed.
- *
- * @return LSUP_OK if entries were found, LSUP_NORESULT if none were found.
- */
-LSUP_MDBIterator *
-LSUP_mdbstore_lookup(
-        LSUP_MDBStore *store, const LSUP_Buffer *ss, const LSUP_Buffer *sp,
-        const LSUP_Buffer *so, const LSUP_Buffer *sc, size_t *ct);
-
-
-/** @brief Yield the matching triples and advance the iterator.
- *
- * This function also checks if the matching triple is associated with a
- * context, if one was specified. If no associated contexts are found, the next
- * triple is searched, until the end of the results.
- *
- * NOTE: Iterators keep LMDB cursors and (read only) transactions open. Don't
- * hold on to them longer than necessary.
- *
- * NOTE: The memory pointed to by the individual LSUP_Buffer pointers is
- * owned by the database. It must not be written to or freed. To modify
- * the data or use them beyond the caller's scope, this memory must be copied.
- *
- * @param[in] it Opaque iterator handle obtained with #LSUP_mdbstore_lookup.
- *
- * @param[out] sspo #LSUP_BufferTriple to be populated with three serialized
- * terms if found, NULL if not found. Internal callers (e.g. counters) may pass
- * NULL if they don't need the serialized triples.
- *
- * @param[out] ctx If not NULL, it is populated with a NULL-terminated array of
- *  LSUP_Buffer structs, one for each context associated with the matching
- *  triple. These contexts are the same regardless of the context filter used
- *  in the lookup. The array is freed with a simple #free().
- *
- *  To iterate over the context array, use this loop:
- *
- *      size_t i = 0;
- *      while (ctx[i].addr)
- *          do_something(ctx + i++); // Buffer data are memory-mapped and RO.
- *
- * @return LSUP_OK if results were found; LSUP_END if no (more) results were
- * found; LSUP_DB_ERR if a MDB_* error occurred.
- */
-LSUP_rc LSUP_mdbiter_next (
-        LSUP_MDBIterator *it, LSUP_BufferTriple *sspo, LSUP_Buffer **ctx);
-
-
-/** @brief Free an iterator allocated by a lookup.
- *
- * @param it[in] Iterator pointer. It will be set to NULL after freeing.
- */
-void LSUP_mdbiter_free (LSUP_MDBIterator *it);
-
-
-/** @brief Get all namespace prefixes in the store.
- *
- * @param[in] store MDB store to query.
- *
- * @param[out] nsm Pointer to namespace map to generate.
- *
- * @return LSUP_OK on success; LSUP_DB_ERR on MDB error.
- */
-LSUP_rc
-LSUP_mdbstore_nsm_get (LSUP_MDBStore *store, LSUP_NSMap **nsm);
-
-
-/** @brief Store an in-memory namespace map into the permanent back end.
- *
- * Existing prefixes and namespaces are not updated. Thus, if the following are
- * already stored:
- *
- * ns1: <urn:ns:a#>
- * ns2: <urn:ns:b#>
- *
- * Neither of the following will be inserted:
- *
- * ns3: <urn:ns:a#>
- * ns2: <urn:ns:c#>
- *
- * @param[in] store MDB store to update.
- *
- * @param[out] nsm Namespace map handle to store.
- *
- * @return LSUP_OK if all terms were updated; LSUP_CONFLICT if one or more
- *  namespaces or terms were not updated because they already existed; <0 if
- *  an error occurred.
- */
-LSUP_rc
-LSUP_mdbstore_nsm_store (LSUP_MDBStore *store, const LSUP_NSMap *nsm);
-
-
-/** @brief Add a single term to the store.
- *
- * @param[in] store MDB store handle.
- *
- * @param[in] sterm Serialized term to store.
- */
-LSUP_rc
-LSUP_mdbstore_add_term (LSUP_MDBStore *store, const LSUP_Buffer *sterm);
-
-
-/** @brief Whether a term key exists.
- *
- * @param[in] store MDB store to search in.
- *
- * @param[in] key Key to look up.
- *
- * @return 1 if the term exists, 0 if it does not exist; <0 on error.
- */
-int
-LSUP_mdbstore_tkey_exists (LSUP_MDBStore *store, LSUP_Key tkey);
+#define LSUP_MDB_STORE_URN "file://" TMPDIR "/mdb_store"
 
+/// MDB store interface.
+extern const LSUP_StoreInt mdbstore_int;
 
 #endif  /* _LSUP_STORE_MDB_H */

src/buffer.c

@@ -2,7 +2,7 @@
 
 /* * * Inline extern prototypes * * */
 
-LSUP_Buffer *LSUP_buffer_new (const size_t size, const void *data);
+LSUP_Buffer *LSUP_buffer_new (const void *data, const size_t size);
 LSUP_rc LSUP_buffer_init (
         LSUP_Buffer *buf, const size_t size, const void *data);
 bool LSUP_buffer_eq (const LSUP_Buffer *buf1, const LSUP_Buffer *buf2);

src/codec/nt_lexer.re

@@ -338,7 +338,7 @@ LSUP_nt_parse_doc (FILE *fh, LSUP_Graph **gr_p, size_t *ct, char **err_p)
     LSUP_rc rc;
 
     LSUP_Graph *gr = LSUP_graph_new (
-            LSUP_iriref_new (NULL, NULL), LSUP_STORE_MEM);
+            LSUP_iriref_new (NULL, NULL), LSUP_STORE_HTABLE, NULL, NULL, 0);
     if (UNLIKELY (!gr)) return LSUP_MEM_ERR;
 
     LSUP_GraphIterator *it = LSUP_graph_add_init (gr);

src/codec_nt.c

@@ -3,13 +3,13 @@
 
 /** @brief List of characters to be escaped in serialized literals.
  *
- * https://www.w3.org/TR/n-triples/#grammar-production-ECHAR
+ * @sa https://www.w3.org/TR/n-triples/#grammar-production-ECHAR
  */
 #define LIT_ECHAR "\t\b\n\r\f\"\'\\"
 
 /** @brief Regex of characters to be escaped in serialized IRIs.
  *
- * https://www.w3.org/TR/n-triples/#grammar-production-IRIREF
+ * @sa https://www.w3.org/TR/n-triples/#grammar-production-IRIREF
  */
 #define IRI_ECHAR_PTN "[\x00-\x20<>\"\\{\\}\\|\\^`\\\\]"
 

src/core.c

@@ -1,4 +1,5 @@
 #define _XOPEN_SOURCE 500
+#include <errno.h>
 #include <ftw.h>
 #include "core.h"
 #include "lmdb.h"
@@ -36,48 +37,51 @@ char *err_msg[] = {
     "LSUP_IO_ERR: Input/Output error.",
     "LSUP_MEM_ERR: Memory error.",
     "LSUP_CONFLICT_ERR: A resource conflict interrupted the operation.",
-    "LSUP_ENV_ERR: Invalid environment. Did you call LSUP_init()?",
+    "LSUP_ENV_ERR: Environment not initialized. Did you call LSUP_init()?",
 };
 
 char *LSUP_root_path = __FILE__; // This is trimmed to root path on init.
 
-int mkdir_p(const char *path, mode_t mode)
+
+LSUP_rc
+mkdir_p (const char *_path, mode_t mode)
 {
-    /* Adapted from http://stackoverflow.com/a/2336245/119527 */
-    const size_t len = strlen(path);
-    char _path[PATH_MAX];
+    char *path = strdup (_path);
     char *p;
 
-    errno = 0;
+    // Trim any trailing slash(es).
+    for (p = path + strlen (path) - 1; p > path; p--)
+        if (*p == '/') *p = '\0';
+        else break;
 
-    /* Copy string so its mutable */
-    if (len > sizeof(_path)-1) {
-        errno = ENAMETOOLONG;
-        return -1;
-    }
-    strcpy(_path, path);
+    errno = 0;
+    LSUP_rc rc = LSUP_NOACTION;
 
     /* Iterate the string */
-    for (p = _path + 1; *p; p++) {
+    for (p = path + 1; *p; p++) {
         if (*p == '/') {
             /* Temporarily truncate */
             *p = '\0';
 
-            if (mkdir(_path, mode) != 0) {
-                if (errno != EEXIST)
-                    return -1;
-            }
+            if (mkdir (path, mode) != 0 && errno != EEXIST) goto finally;
 
             *p = '/';
         }
     }
-
-    if (mkdir(_path, mode) != 0) {
-        if (errno != EEXIST)
-            return -1;
+    if (mkdir (path, mode) != 0) {
+        if (errno != EEXIST) rc = errno;
+    } else {
+        rc = LSUP_OK;
     }
 
-    return 0;
+finally:
+
+    log_trace ("Path: %s", path);
+    log_trace ("errno: %d", errno);
+    log_trace ("rc: %d", rc);
+    free (path);
+
+    return rc;
 }
 
 

src/environment.c

@@ -1,30 +1,35 @@
-#include <unistd.h>
-
-#include "term.h"
 #include "environment.h"
+#include "data/bootstrap.h"
 
 
-/**
- * Static handles.
+/** @brief Default context.
+ *
+ * The actual default context IRI used throughout the application may use a
+ * value from the `LSUP_DEFAULT_CTX_URI` environment variable.
  */
-#define DEFAULT_CTX_LABEL "urn:lsup:default"
+#define DEFAULT_CTX_LABEL LSUP_NS "default"
 
 
-/** @brief Environment "singleton".
+/*
+ * External variables.
  */
-LSUP_Env *LSUP_default_env = NULL;
+LSUP_NSMap *LSUP_default_nsm = NULL;
+LSUP_Term *LSUP_default_ctx = NULL;
+LSUP_Buffer *LSUP_default_ctx_buf = NULL;
 
 
 /*
  * Hashmap callbacks.
  */
 
-static uint64_t term_cache_hash_fn (
+static uint64_t
+term_cache_hash_fn (
         const void *item, uint64_t seed0, uint64_t seed1)
 { return ((const LSUP_KeyedTerm *) item)->key; }
 
 
-static int term_cache_cmp_fn (const void *a, const void *b, void *udata)
+static int
+term_cache_cmp_fn (const void *a, const void *b, void *udata)
 {
     return 
             ((const LSUP_KeyedTerm *) a)->key -
@@ -32,7 +37,8 @@ static int term_cache_cmp_fn (const void *a, const void *b, void *udata)
 }
 
 
-static void term_cache_free_fn (void *item)
+static void
+term_cache_free_fn (void *item)
 { LSUP_term_free (((LSUP_KeyedTerm *) item)->term); }
 
 
@@ -40,39 +46,13 @@ static void term_cache_free_fn (void *item)
  * API
  */
 
-LSUP_Env *
-LSUP_env_new (
-        const char *default_ctx, const char *mdb_path,
-        const LSUP_NSMap *nsmap)
-{
-    LSUP_Env *env;
-    CALLOC_GUARD (env, NULL);
-
-    // Default store context.
-    LSUP_Term *default_ctx_uri = LSUP_iriref_new (default_ctx, NULL);
-    env->default_ctx = LSUP_term_serialize (default_ctx_uri);
-    LSUP_term_free (default_ctx_uri);
-    log_info ("Set up default context.");
-
-    // Set up store if not existing.
-    if (LSUP_mdbstore_setup (mdb_path, false) != LSUP_OK) return NULL;
-    env->mdb_store = LSUP_mdbstore_new (mdb_path, env->default_ctx);
-    if (UNLIKELY (!env->mdb_store)) return NULL;
-    log_info ("Initialized persistent back end at %s.", mdb_path);
-
-    // Get default namespace from store.
-    RCNL (LSUP_mdbstore_nsm_get (env->mdb_store, &env->nsm));
-
-    return env;
-}
-
-
 LSUP_rc
 LSUP_init (void)
 {
-    LSUP_rc rc = LSUP_NOACTION;
-
-    if (LSUP_env_is_init) return rc;
+    if (LSUP_IS_INIT) {
+        LOG_RC (LSUP_NOACTION);
+        return LSUP_NOACTION;
+    }
 
 #ifdef DEBUG
     // In debug mode, always use max logging.
@@ -85,7 +65,8 @@ LSUP_init (void)
 
     // URI validation pattern.
     MALLOC_GUARD (LSUP_uri_ptn, LSUP_MEM_ERR);
-    /* Uncomment in case a change in the URI regex results in an error.
+
+#if 0 // Re-activate in case a change in the URI regex results in an error.
     int regex_rc = regcomp (LSUP_uri_ptn, LSUP_URI_REGEX_STR, REG_EXTENDED);
     if (regex_rc != 0) {
         char err_msg[128];
@@ -95,11 +76,26 @@ LSUP_init (void)
                 err_msg);
         return LSUP_ERROR;
     }
-    */
+#else
     if (regcomp (LSUP_uri_ptn, LSUP_URI_REGEX_STR, REG_EXTENDED) != 0) {
         log_error ("Error compiling regular expression pattern.");
         return LSUP_ERROR;
     }
+#endif
+
+    // Default namespace map.
+    LSUP_default_nsm = LSUP_nsmap_new();
+    if (UNLIKELY (!LSUP_default_nsm)) return LSUP_ERROR;
+    for (int i = 0; init_nsmap[i][0] != NULL; i++)
+        LSUP_nsmap_add (LSUP_default_nsm, init_nsmap[i][0], init_nsmap[i][1]);
+
+    // Default context URI.
+    char *default_ctx_str = getenv ("LSUP_DEFAULT_CTX");
+    if (!default_ctx_str ) default_ctx_str = DEFAULT_CTX_LABEL;
+    LSUP_default_ctx = LSUP_iriref_new (default_ctx_str, LSUP_default_nsm);
+    if (UNLIKELY (!LSUP_default_ctx)) return LSUP_ERROR;
+    LSUP_default_ctx_buf = LSUP_term_serialize (LSUP_default_ctx);
+    if (UNLIKELY (!LSUP_default_ctx_buf)) return LSUP_ERROR;
 
     // Initialize term cache.
     LSUP_term_cache = hashmap_new (
@@ -110,69 +106,34 @@ LSUP_init (void)
     uint32_t dtype_hash = LSUP_term_hash (LSUP_default_datatype );
     LSUP_tcache_add (dtype_hash, LSUP_default_datatype);
 
-    // Default permanent store path.
-    char *mdb_path = getenv ("LSUP_MDB_STORE_PATH");
-    if (!mdb_path) {
-        mdb_path = DEFAULT_ENV_PATH;
-        log_warn (
-            "`LSUP_MDB_STORE_PATH' environment variable is not "
-            "set. The default location %s will be used as the graph "
-            "store.", mdb_path
-        );
-    }
-
-    // Default permanent store.
-    LSUP_default_env = LSUP_env_new (
-            DEFAULT_CTX_LABEL, mdb_path, NULL);
-    if (UNLIKELY (!LSUP_default_env)) return LSUP_ERROR;
-
-    // RAM disk store.
-    if (LSUP_mdbstore_setup (LSUP_MDB_RAMDISK_PATH, true) != LSUP_OK) {
-        log_error ("Error setting up RAM disk store files.");
-        return LSUP_DB_ERR;
-    }
-
-    LSUP_default_env->mdb_store_ramdisk = LSUP_mdbstore_new (
-            LSUP_MDB_RAMDISK_PATH, LSUP_default_env->default_ctx);
-    if (UNLIKELY (!LSUP_default_env->mdb_store_ramdisk)) {
-        log_error ("Error setting up RAM disk store.");
-        return LSUP_DB_ERR;
-    }
-
-    log_info ("Initialized RAM disk back end at %s.", LSUP_MDB_RAMDISK_PATH);
-
     // Set automatic teardown TODO Is this a good idea?
     atexit (LSUP_done);
 
-    LSUP_env_is_init = true;
-
     return LSUP_OK;
 }
 
 
-void
-LSUP_env_free (LSUP_Env *env)
-{
-    LSUP_mdbstore_free (env->mdb_store);
-    LSUP_mdbstore_free (env->mdb_store_ramdisk);
-    LSUP_buffer_free (env->default_ctx);
-    LSUP_nsmap_free (env->nsm);
-
-    free (env);
-}
-
-
 void
 LSUP_done (void)
 {
-    if (!LSUP_env_is_init) return;
+    if (!LSUP_IS_INIT) return;
 
-    LSUP_env_free (LSUP_default_env);
     regfree (LSUP_uri_ptn);
     free (LSUP_uri_ptn);
 
+    // Free default NS map and context.
+    LSUP_buffer_free (LSUP_default_ctx_buf);
+    LSUP_term_free (LSUP_default_ctx);
+    LSUP_nsmap_free (LSUP_default_nsm);
+
     // Free ID cache, including default literal datatype.
     hashmap_free (LSUP_term_cache);
-
-    LSUP_env_is_init = false;
+    LSUP_term_cache = NULL; // This causes LSUP_IS_INIT to return false.
 }
+
+
+/*
+ * Extern inline prototypes.
+ */
+
+bool LSUP_is_init (void);

src/graph.c

@@ -1,36 +1,21 @@
-#include "store_htable.h"
-#include "store_mdb.h"
 #include "graph.h"
 
-
 /*
  * Data types.
  */
 
-typedef struct Graph {
-    const LSUP_Env *        env;            // LSUP environment.
-    LSUP_store_type         store_type;     // Back end type: in-memory or MDB.
-    LSUP_Term               *uri;           // Graph "name" (URI)
-    union {
-        LSUP_HTStore *      ht_store;
-        LSUP_MDBStore *     mdb_store;
-    };                                      // Back end, defined by store_type.
-    LSUP_NSMap *            nsm;            // Namespace map. NOTE: This is
-                                            // NULL for MDB* stores. To get a
-                                            // proper NSMap, always call
-                                            // #LSUP_graph_namespace() for all
-                                            // types of graphs.
-} Graph;
-
-
-typedef struct GraphIterator {
-    const Graph *           graph;      // Parent graph.
-    union {                             // Internal store iterator.
-        LSUP_HTIterator *   ht_iter;
-        LSUP_MDBIterator *  mdb_iter;
-    };
-    size_t                  ct;         // Total matches.
-} GraphIterator;
+struct graph_t {
+    LSUP_Term               *uri;           ///< Graph "name" (URI).
+    LSUP_Store *            store;          ///< Store handle.
+    LSUP_NSMap *            nsm;            /**< Namespace map. NOTE: This is
+                                               * NULL for permanent stores. */
+};
+
+struct graph_iter_t {
+    LSUP_Store *            store;          ///< Store tied to the iterator.
+    void *                  data;           ///< Iterator state.
+    size_t                  ct;             ///< Total lookup matches.
+};
 
 
 /*
@@ -38,14 +23,11 @@ typedef struct GraphIterator {
  */
 
 inline static LSUP_rc
-graph_iter_next_buffer (GraphIterator *it, LSUP_BufferTriple *sspo);
-
-static LSUP_rc
-graph_copy_contents (const LSUP_Graph *src, LSUP_Graph *dest);
+graph_iter_next_buffer (LSUP_GraphIterator *it, LSUP_BufferTriple *sspo);
 
 #define ENTRY(a, b) (be) == (LSUP_STORE_##a) ||
 static inline bool
-check_backend (LSUP_store_type be)
+check_backend (LSUP_StoreType be)
 { return (BACKEND_TBL false); }
 #undef ENTRY
 
@@ -54,12 +36,14 @@ check_backend (LSUP_store_type be)
  * Graph API.
  */
 
-Graph *
-LSUP_graph_new_env (
-        const LSUP_Env *env, LSUP_Term *uri, const LSUP_store_type store_type)
+LSUP_Graph *
+LSUP_graph_new (
+        LSUP_Term *uri, const LSUP_StoreType store_type, const char *store_id,
+        LSUP_NSMap *nsm, size_t size)
 {
-    if (UNLIKELY (!env)) {
-        log_error ("No valid environment passed. Did you call LSUP_init()?");
+    if (UNLIKELY (!LSUP_IS_INIT)) {
+        log_error (
+                "Environment is not initialized. Did you call LSUP_init()?");
         return NULL;
     }
     if (UNLIKELY (!check_backend (store_type))) return NULL;
@@ -68,110 +52,117 @@ LSUP_graph_new_env (
     MALLOC_GUARD (gr, NULL);
 
     gr->uri = uri;
-    gr->store_type = store_type;
-    gr->env = env;
-    gr->nsm = env->nsm;
+    MALLOC_GUARD (gr->store, NULL);
 
-    if (gr->store_type == LSUP_STORE_MEM) {
-        gr->ht_store = LSUP_htstore_new(0);
-        if (UNLIKELY (!gr->ht_store)) return NULL;
+    gr->store->type = store_type;
+    gr->store->id = store_id ? strdup (store_id) : NULL;
 
-    } else if (gr->store_type == LSUP_STORE_MDB) {
-        gr->mdb_store = env->mdb_store;
+    switch (gr->store->type) {
+#define ENTRY(a, b) \
+        case LSUP_STORE_##a: gr->store->sif = &b; break;
+BACKEND_TBL
+#undef ENTRY
+        default:
+            log_error ("Not a valid store type: %d", store_type); return NULL;
+    };
 
-    } else { // LSUP_STORE_MDB_TMP
-        gr->mdb_store = env->mdb_store_ramdisk;
-    }
+    // TODO implement custom default context.
+    gr->store->data = gr->store->sif->new_fn (store_id, size);
+
+    if (gr->store->sif->features & LSUP_STORE_PERM) gr->nsm = NULL;
+    else gr->nsm = nsm ? nsm : LSUP_default_nsm;
 
     log_debug ("Graph created.");
     return gr;
 }
 
 
-LSUP_Graph *
-LSUP_graph_copy (const Graph *src)
-{
-    LSUP_Graph *dest = LSUP_graph_new_env (
-            src->env, LSUP_iriref_new (NULL, NULL), src->store_type);
-    if (UNLIKELY (!dest)) return NULL;
-
-    LSUP_rc rc = graph_copy_contents (src, dest);
-    if (UNLIKELY (rc != LSUP_OK)) return NULL;
-
-    return dest;
-}
-
-
 LSUP_rc
-LSUP_graph_store (
-        const LSUP_Graph *src, LSUP_Graph **dest_p, const LSUP_Env *env)
+LSUP_graph_bool_op(
+        const LSUP_bool_op op, const LSUP_Graph *gr1, const LSUP_Graph *gr2,
+        LSUP_Graph *res)
 {
-    if (!env) env = LSUP_default_env;
-    if (src->store_type == LSUP_STORE_MDB && src->env == env)
-        return LSUP_NOACTION;
-
-    LSUP_Graph *dest = LSUP_graph_new_env (
-            env, LSUP_iriref_new (src->uri->data, LSUP_iriref_nsm (src->uri)),
-            LSUP_STORE_MDB);
-    if (UNLIKELY (!dest)) return LSUP_DB_ERR;
-
-    LSUP_rc rc;
-    rc = graph_copy_contents (src, dest);
-    if (UNLIKELY (rc < 0)) return LSUP_DB_ERR;
+    LSUP_rc rc = LSUP_NOACTION;
+    if (UNLIKELY (
+            op != LSUP_BOOL_UNION
+            && op != LSUP_BOOL_SUBTRACTION
+            && op != LSUP_BOOL_INTERSECTION
+            && op != LSUP_BOOL_XOR)) {
+        log_error ("Invalid boolean operation: %d.", op);
 
-    if (src->store_type == LSUP_STORE_MEM) {
-        rc = LSUP_mdbstore_nsm_store (dest->mdb_store, src->nsm);
-        if (UNLIKELY (rc < 0)) return LSUP_DB_ERR;
+        return LSUP_VALUE_ERR;
     }
 
-    if (dest_p) *dest_p = dest;
-    else LSUP_graph_free (dest);
-
-    return LSUP_OK;
-}
+    if (op == LSUP_BOOL_UNION) {
+        rc = LSUP_graph_copy_contents (gr1, res);
+        PCHECK (rc, fail);
+        rc = LSUP_graph_copy_contents (gr2, res);
+        PCHECK (rc, fail);
 
+        return LSUP_OK;
+    }
 
-// TODO support boolean ops between any types of graphs.
-Graph *
-LSUP_graph_bool_op(
-        const LSUP_bool_op op, const Graph *gr1, const Graph *gr2)
-{
-    if (UNLIKELY (gr1->store_type != LSUP_STORE_MEM)) {
-        fprintf(
-                stderr,
-                "First operand %s is not an in-memory graph. "
-                "Cannot perform boolean operation.",
-                gr1->uri->data);
-        return NULL;
+    LSUP_Buffer
+        *res_sc = LSUP_term_serialize (res->uri),
+        *gr1_sc = LSUP_term_serialize (gr1->uri),
+        *gr2_sc = LSUP_term_serialize (gr2->uri);
+    void *lu1_it, *lu2_it, *add_it;
+    LSUP_BufferTriple *sspo = BTRP_DUMMY;
+    size_t ct;
+
+    add_it = res->store->sif->add_init_fn (res->store->data, res_sc);
+
+    if (op == LSUP_BOOL_XOR) {
+        // Add triples from gr2 if not found in gr1.
+        lu2_it = gr2->store->sif->lookup_fn (
+                gr2->store->data, NULL, NULL, NULL, gr2_sc, NULL);
+        while (gr2->store->sif->lu_next_fn (lu2_it, sspo, NULL) == LSUP_OK) {
+            lu1_it = gr1->store->sif->lookup_fn (
+                    gr1->store->data, sspo->s, sspo->p, sspo->o, gr1_sc, &ct);
+            if (ct > 0)
+                res->store->sif->add_iter_fn (add_it, sspo);
+            gr1->store->sif->lu_free_fn (lu1_it);
+        }
+        gr2->store->sif->lu_free_fn (lu2_it);
     }
-    if (UNLIKELY (gr2->store_type != LSUP_STORE_MEM)) {
-        fprintf(
-                stderr,
-                "Second operand %s is not an in-memory graph. "
-                "Cannot perform boolean operation.",
-                gr2->uri->data);
-        return NULL;
+
+    lu1_it = gr1->store->sif->lookup_fn (
+            gr1->store->data, NULL, NULL, NULL, gr1_sc, NULL);
+    while (gr1->store->sif->lu_next_fn (lu1_it, sspo, NULL) == LSUP_OK) {
+        lu2_it = gr2->store->sif->lookup_fn (
+                gr2->store->data, sspo->s, sspo->p, sspo->o, gr2_sc, &ct);
+        // For XOR and subtraction, add if not found.
+        // For intersection, add if found.
+        if ((ct == 0) ^ (op == LSUP_BOOL_INTERSECTION))
+            res->store->sif->add_iter_fn (add_it, sspo);
+        gr2->store->sif->lu_free_fn (lu2_it);
     }
+    gr1->store->sif->lu_free_fn (lu1_it);
+
+    res->store->sif->add_done_fn (add_it);
+    LSUP_buffer_free (res_sc);
+    LSUP_buffer_free (gr1_sc);
+    LSUP_buffer_free (gr2_sc);
 
-    LSUP_Graph *res = LSUP_graph_new (
-            LSUP_iriref_new (NULL, NULL), LSUP_STORE_MEM);
-    res->ht_store = LSUP_htstore_bool_op (op, gr1->ht_store, gr2->ht_store);
+    return rc;
 
-    return res;
+fail:
+    LSUP_graph_free (res);
+    return rc;
 }
 
 
 void
 LSUP_graph_free (LSUP_Graph *gr)
 {
-    if (LIKELY (gr != NULL)) {
-        LSUP_term_free (gr->uri);
+    if (UNLIKELY (!gr)) return;
 
-        if (gr->store_type == LSUP_STORE_MEM)
-            LSUP_htstore_free (gr->ht_store);
+    LSUP_term_free (gr->uri);
+    free (gr->store->id);
+    gr->store->sif->free_fn (gr->store->data);
+    free (gr->store);
 
-        free (gr);
-    }
+    free (gr);
 }
 
 
@@ -195,61 +186,53 @@ LSUP_graph_set_uri (LSUP_Graph *gr, LSUP_Term *uri)
 
 
 LSUP_NSMap *
-LSUP_graph_namespace (const Graph *gr)
+LSUP_graph_namespace (const LSUP_Graph *gr)
 {
-    if (gr->store_type == LSUP_STORE_MEM) return gr->nsm;
+    // If nsm_get_fn is not defined, the store has no own NS map.
+    if (!gr->store->sif->nsm_get_fn) return gr->nsm;
 
-    LSUP_NSMap *nsm;
-    if (LSUP_mdbstore_nsm_get (gr->mdb_store, &nsm) < 0) return NULL;
-    return nsm;
+    return gr->store->sif->nsm_get_fn (gr->store->data);
 }
 
 
 void
-LSUP_graph_set_namespace (Graph *gr, LSUP_NSMap *nsm)
-{ if (gr->store_type == LSUP_STORE_MEM) gr->nsm = nsm; }
-
-
-size_t
-LSUP_graph_size (const Graph *gr)
+LSUP_graph_set_namespace (LSUP_Graph *gr, LSUP_NSMap *nsm)
 {
-    if (gr->store_type == LSUP_STORE_MEM)
-        return LSUP_htstore_size (gr->ht_store);
-    else {
-        size_t ct;
-        LSUP_GraphIterator *it = LSUP_graph_lookup (gr, NULL, NULL, NULL, &ct);
+    if (!gr->store->sif->nsm_get_fn) gr->nsm = nsm;
+    else log_warn ("Graph back end has a stored NS map.");
+}
 
-        LSUP_graph_iter_free (it);
 
-        return ct;
-    }
-}
+size_t
+LSUP_graph_size (const LSUP_Graph *gr)
+{ return gr->store->sif->size_fn (gr->store->data); }
 
 
 bool
-LSUP_graph_equals (const Graph *gr1, const Graph *gr2)
+LSUP_graph_equals (const LSUP_Graph *gr1, const LSUP_Graph *gr2)
 {
-    LSUP_Graph *res = LSUP_graph_bool_op (LSUP_BOOL_XOR, gr1, gr2);
+    LSUP_Graph *res = LSUP_graph_new (NULL, LSUP_STORE_HTABLE, NULL, NULL, 0);
+    LSUP_graph_bool_op (LSUP_BOOL_XOR, gr1, gr2, res);
+    bool ret = (LSUP_graph_size (res) == 0);
 
-    return (LSUP_graph_size (res) == 0);
+    LSUP_graph_free (res);
+
+    return ret;
 }
 
 
-GraphIterator *
+LSUP_GraphIterator *
 LSUP_graph_add_init (LSUP_Graph *gr)
 {
-    GraphIterator *it;
+    LSUP_GraphIterator *it;
     CALLOC_GUARD (it, NULL);
 
-    if (gr->store_type == LSUP_STORE_MEM) {
-        it->ht_iter = LSUP_htstore_add_init (gr->ht_store);
-    } else {
-        LSUP_Buffer *sc = LSUP_term_serialize (gr->uri);
-        it->mdb_iter = LSUP_mdbstore_add_init (gr->mdb_store, sc);
-        LSUP_buffer_free (sc);
-    }
+    LSUP_Buffer *sc = LSUP_term_serialize (gr->uri);
 
-    it->graph = gr;
+    it->data = gr->store->sif->add_init_fn (gr->store->data, sc);
+    LSUP_buffer_free (sc);
+
+    it->store = gr->store;
 
     return it;
 }
@@ -258,40 +241,27 @@ LSUP_graph_add_init (LSUP_Graph *gr)
 LSUP_rc
 LSUP_graph_add_iter (LSUP_GraphIterator *it, const LSUP_Triple *spo)
 {
-    LSUP_rc rc;
 
     LSUP_BufferTriple *sspo = LSUP_triple_serialize (spo);
     if (UNLIKELY (!sspo)) return LSUP_MEM_ERR;
 
-    if (it->graph->store_type == LSUP_STORE_MEM) {
-        rc = LSUP_htstore_add_iter (it->ht_iter, sspo);
+    LSUP_rc rc = it->store->sif->add_iter_fn (it->data, sspo);
+    PCHECK (rc, finally);
 
+    // Store datatype term permanently if the store supports it.
+    if (rc == LSUP_OK && it->store->sif->add_term_fn) {
         for (int i = 0; i < 3; i++) {
-            LSUP_htstore_add_term (
-                    it->graph->ht_store, LSUP_btriple_pos (sspo, i));
-            // HT store uses term keys from tcache.
-        }
-    } else {
-        rc = LSUP_mdbstore_add_iter (it->mdb_iter, sspo);
-
-        for (int i = 0; i < 3; i++) {
-            LSUP_mdbstore_add_term (
-                    it->graph->mdb_store, LSUP_btriple_pos (sspo, i));
-
-            // Store datatype term permanently.
             LSUP_Term *term = LSUP_triple_pos (spo, i);
-            if (
-                term->type == LSUP_TERM_LITERAL
-                && !LSUP_mdbstore_tkey_exists (
-                        it->graph->mdb_store, LSUP_term_hash (term->datatype))
-            ) {
+            if (term->type == LSUP_TERM_LITERAL) {
                 LSUP_Buffer *ser_dtype = LSUP_term_serialize (term->datatype);
-                LSUP_mdbstore_add_term (it->graph->mdb_store, ser_dtype);
+                it->store->sif->add_term_fn (it->store->data, ser_dtype);
                 LSUP_buffer_free (ser_dtype);
             }
         }
     }
 
+
+finally:
     LSUP_btriple_free (sspo);
 
     return rc;
@@ -301,17 +271,13 @@ LSUP_graph_add_iter (LSUP_GraphIterator *it, const LSUP_Triple *spo)
 void
 LSUP_graph_add_done (LSUP_GraphIterator *it)
 {
-    if (it->graph->store_type == LSUP_STORE_MEM)
-        LSUP_htstore_add_done (it->ht_iter);
-    else LSUP_mdbstore_add_done (it->mdb_iter);
-
+    it->store->sif->add_done_fn (it->data);
     free (it);
-    log_trace ("Done adding.");
 }
 
 
 LSUP_rc
-LSUP_graph_add (Graph *gr, const LSUP_Triple trp[], size_t *ct)
+LSUP_graph_add (LSUP_Graph *gr, const LSUP_Triple trp[], size_t *ct)
 {
     LSUP_rc rc = LSUP_NOACTION;
 
@@ -331,9 +297,13 @@ LSUP_graph_add (Graph *gr, const LSUP_Triple trp[], size_t *ct)
             // A duplicate will return LSUP_NOACTION and not increment the
             // counter.
         }
-        if (UNLIKELY (db_rc < 0)) return db_rc;
+        if (UNLIKELY (db_rc < 0)) {
+            rc = db_rc;
+            goto finally;
+        }
     }
 
+finally:
     LSUP_graph_add_done (it);
 
     return rc;
@@ -353,10 +323,7 @@ LSUP_graph_remove (
         *so = LSUP_term_serialize (o),
         *sc = LSUP_term_serialize (gr->uri);
 
-    if (gr->store_type == LSUP_STORE_MEM)
-        rc = LSUP_htstore_remove (gr->ht_store, ss, sp, so, ct);
-    else
-        rc = LSUP_mdbstore_remove (gr->mdb_store, ss, sp, so, sc, ct);
+    rc = gr->store->sif->remove_fn (gr->store->data, ss, sp, so, sc, ct);
 
     LSUP_buffer_free (ss);
     LSUP_buffer_free (sp);
@@ -367,26 +334,59 @@ LSUP_graph_remove (
 }
 
 
-GraphIterator *
-LSUP_graph_lookup (const Graph *gr, const LSUP_Term *s, const LSUP_Term *p,
+/**
+ * Copy triples from a source graph into a destination one.
+ *
+ * The destination graph is not initialized here, so the copy is cumulative.
+ */
+LSUP_rc
+LSUP_graph_copy_contents (const LSUP_Graph *src, LSUP_Graph *dest)
+{
+    LSUP_rc rc = LSUP_NOACTION;
+
+    LSUP_GraphIterator *it = LSUP_graph_lookup (src, NULL, NULL, NULL, NULL);
+
+    LSUP_Triple spo;
+
+    LSUP_GraphIterator *add_it = LSUP_graph_add_init (dest);
+    while (LSUP_graph_iter_next (it, &spo) != LSUP_END) {
+        LSUP_rc add_rc = LSUP_graph_add_iter (add_it, &spo);
+        LSUP_triple_done (&spo);
+        if (LIKELY (add_rc == LSUP_OK)) rc = LSUP_OK;
+        else if (add_rc < 0) {
+            rc = add_rc;
+            break;
+        }
+    }
+
+    LSUP_graph_add_done (add_it);
+    LSUP_graph_iter_free (it);
+
+    return rc;
+}
+
+
+LSUP_GraphIterator *
+LSUP_graph_lookup (
+        const LSUP_Graph *gr, const LSUP_Term *s, const LSUP_Term *p,
         const LSUP_Term *o, size_t *ct)
 {
-    GraphIterator *it;
+    LSUP_GraphIterator *it;
     MALLOC_GUARD (it, NULL);
 
-    it->graph = gr;
-
-    LSUP_Buffer *ss = LSUP_term_serialize (s);
-    LSUP_Buffer *sp = LSUP_term_serialize (p);
-    LSUP_Buffer *so = LSUP_term_serialize (o);
-    LSUP_Buffer *sc = LSUP_term_serialize (gr->uri);
+    it->store = gr->store;
 
-    if (it->graph->store_type == LSUP_STORE_MEM)
-        it->ht_iter = LSUP_htstore_lookup (
-                it->graph->ht_store, ss, sp, so, ct);
+    LSUP_Buffer
+        *ss = LSUP_term_serialize (s),
+        *sp = LSUP_term_serialize (p),
+        *so = LSUP_term_serialize (o),
+        *sc = LSUP_term_serialize (gr->uri);
 
-    else it->mdb_iter = LSUP_mdbstore_lookup (
-            it->graph->mdb_store, ss, sp, so, sc, ct);
+    it->data = it->store->sif->lookup_fn (it->store->data, ss, sp, so, sc, ct);
+    if (UNLIKELY (!it->data)) {
+        free (it);
+        it = NULL;
+    }
 
     LSUP_buffer_free (ss);
     LSUP_buffer_free (sp);
@@ -398,27 +398,18 @@ LSUP_graph_lookup (const Graph *gr, const LSUP_Term *s, const LSUP_Term *p,
 
 
 LSUP_rc
-LSUP_graph_iter_next (GraphIterator *it, LSUP_Triple *spo)
+LSUP_graph_iter_next (LSUP_GraphIterator *it, LSUP_Triple *spo)
 {
-    /*
-     * NOTE: Memory and MDB back ends treat sspo differently, whereas the
-     * memory one owns the whole buffer structure, while the MDB one owns only
-     * the data. Therefore they must be initialized and freed differently.
-     */
-
-    LSUP_BufferTriple *sspo;
     LSUP_Buffer *ss, *sp, *so;
-
-    if (it->graph->store_type == LSUP_STORE_MEM) {
-        ss = sp = so = NULL;
-    } else {
-        // Craft buffers manually so that their addresses are NULL and need not
-        // be freed.
+    LSUP_BufferTriple *sspo;
+    if (it->store->sif->features & LSUP_STORE_COW) {
         CALLOC_GUARD (ss, LSUP_MEM_ERR);
         CALLOC_GUARD (sp, LSUP_MEM_ERR);
         CALLOC_GUARD (so, LSUP_MEM_ERR);
+        sspo = LSUP_btriple_new (ss, sp, so);
+    } else {
+        // TODO copy-on-retrieval stores. None yet.
     }
-    sspo = LSUP_btriple_new (ss, sp, so);
 
     LSUP_rc rc = graph_iter_next_buffer (it, sspo);
 
@@ -431,21 +422,20 @@ LSUP_graph_iter_next (GraphIterator *it, LSUP_Triple *spo)
         if (!spo->o) return LSUP_ERROR;
     }
 
-    if (it->graph->store_type == LSUP_STORE_MEM) free (sspo);
-    else LSUP_btriple_free_shallow (sspo);
+    if (it->store->sif->features & LSUP_STORE_COW) {
+        LSUP_btriple_free_shallow (sspo);
+    } else {
+        // TODO copy-on-retrieval stores. None yet.
+    }
 
     return rc;
 }
 
 
 void
-LSUP_graph_iter_free (GraphIterator *it)
+LSUP_graph_iter_free (LSUP_GraphIterator *it)
 {
-    if (it->graph->store_type == LSUP_STORE_MEM)
-        LSUP_htiter_free (it->ht_iter);
-    else
-        LSUP_mdbiter_free (it->mdb_iter);
-
+    it->store->sif->lu_free_fn (it->data);
     free (it);
 }
 
@@ -453,7 +443,7 @@ LSUP_graph_iter_free (GraphIterator *it)
 bool
 LSUP_graph_contains (const LSUP_Graph *gr, const LSUP_Triple *spo)
 {
-    GraphIterator *it = LSUP_graph_lookup (
+    LSUP_GraphIterator *it = LSUP_graph_lookup (
             gr, spo->s, spo->p, spo->o, NULL);
     LSUP_Triple *tmp_spo = TRP_DUMMY;
     bool rc = LSUP_graph_iter_next (it, tmp_spo) != LSUP_END;
@@ -469,54 +459,14 @@ LSUP_graph_contains (const LSUP_Graph *gr, const LSUP_Triple *spo)
  * Static functions.
  */
 
-/** @brief Advance iterator and return serialized triple.
+/** @brief Advance an iterator and return a serialized triple.
  *
  * This is an internal function to pass raw buffers between higher-level
  * functions without serializing and deserializing triples.
  */
 inline static LSUP_rc
-graph_iter_next_buffer (GraphIterator *it, LSUP_BufferTriple *sspo)
-{
-    LSUP_rc rc;
-
-    if (it->graph->store_type == LSUP_STORE_MEM)
-        rc = LSUP_htiter_next (it->ht_iter, sspo);
-    else rc = LSUP_mdbiter_next (it->mdb_iter, sspo, NULL);
-
-    return rc;
-}
-
-
-/**
- * Copy triples from a source graph into a destination one.
- *
- * The destination graph is not initialized here, so the copy is cumulative.
- */
-static LSUP_rc
-graph_copy_contents (const LSUP_Graph *src, LSUP_Graph *dest)
-{
-    LSUP_rc rc = LSUP_NOACTION;
-
-    GraphIterator *it = LSUP_graph_lookup (src, NULL, NULL, NULL, NULL);
-
-    LSUP_Triple spo;
-
-    LSUP_GraphIterator *add_it = LSUP_graph_add_init (dest);
-    while (LSUP_graph_iter_next (it, &spo) != LSUP_END) {
-        LSUP_rc add_rc = LSUP_graph_add_iter (add_it, &spo);
-        LSUP_triple_done (&spo);
-        if (LIKELY (add_rc == LSUP_OK)) rc = LSUP_OK;
-        else if (add_rc < 0) {
-            rc = add_rc;
-            break;
-        }
-    }
-
-    LSUP_graph_add_done (add_it);
-    LSUP_graph_iter_free (it);
-
-    return rc;
-}
+graph_iter_next_buffer (LSUP_GraphIterator *it, LSUP_BufferTriple *sspo)
+{ return it->store->sif->lu_next_fn (it->data, sspo, NULL); }
 
 
 /**

src/store.c

@@ -0,0 +1,13 @@
+#include "store.h"
+
+
+const LSUP_StoreInt *
+LSUP_store_int (LSUP_StoreType type) {
+    switch (type) {
+#define ENTRY(a, b) \
+        case LSUP_STORE_##a: return &b;
+BACKEND_TBL
+#undef ENTRY
+        default: return NULL;
+    }
+}

src/store_htable.c

@@ -11,24 +11,25 @@ typedef bool (*LSUP_key_eq_fn_t)(
 
 
 typedef struct idx_entry_t {
-    LSUP_Key            key;        ///> Serialized term key.
-    LSUP_Buffer *       sterm;      ///> Serialized term.
+    LSUP_Key            key;        ///< Serialized term key.
+    void *              data;       ///< Serialized term data.
+    size_t              size;       ///< Serialized term size.
 } IndexEntry;
 
 typedef struct ht_store_t {
-    struct hashmap *    keys;       ///> Triple keys (set).
-    struct hashmap *    idx;        ///> Map of keys to serialized terms.
+    struct hashmap *    keys;       ///< Triple keys (set).
+    struct hashmap *    idx;        ///< Map of keys to serialized terms.
 } HTStore;
 
 typedef struct ht_iterator_t {
-    HTStore *           store;      ///> Store being iterated.
-    size_t              cur;        ///> Internal hash table cursor.
-    LSUP_Key            luk[3];     ///> 0÷3 lookup keys.
-    LSUP_key_eq_fn_t    eq_fn;      ///> Equality function to test triples.
-    int                 rc;         ///> Return code for *next* result.
-                                    ///> When the end of results is reached,
-                                    ///> this is set to LSUP_END.
-    LSUP_TripleKey *    entry;      ///> Retrieved SPO key.
+    HTStore *           store;      ///< Store being iterated.
+    size_t              cur;        ///< Internal hash table cursor.
+    LSUP_Key            luk[3];     ///< 0÷3 lookup keys.
+    LSUP_key_eq_fn_t    eq_fn;      ///< Equality function to test triples.
+    int                 rc;         ///< Return code for *next* result.
+                                    ///< When the end of results is reached,
+                                    ///< this is set to LSUP_END.
+    LSUP_TripleKey *    entry;      ///< Retrieved SPO key.
 } HTIterator;
 
 
@@ -119,7 +120,7 @@ static int htstore_idx_cmp_fn (const void *a, const void *b, void *udata)
  * Delete callback function for hashmap.
  */
 static void htstore_idx_free_fn (void *item)
-{ LSUP_buffer_free (((IndexEntry *) item)->sterm); }
+{ free (((IndexEntry *) item)->data); }
 
 
 /* * * Other prototypes. * * */
@@ -141,10 +142,22 @@ static LSUP_rc
 htiter_next_key (HTIterator *it);
 
 
-/* * * API * * */
+/*
+ * Interface members.
+ */
 
-HTStore *
-LSUP_htstore_new (const size_t size)
+/** @brief Create a store for an individual graph.
+ *
+ * @param[in] id Graph identifier. This may or may not be set. The store does
+ *  not use this value internally, and does not check for duplicates.
+ *
+ * @param[in] size Initial size of the store (in number of triples). It may be
+ *  0.
+ *
+ * @return New graph store.
+ */
+void *
+htstore_new (const char *id, size_t size)
 {
     HTStore *ht;
     CALLOC_GUARD (ht, NULL);
@@ -163,23 +176,9 @@ LSUP_htstore_new (const size_t size)
 }
 
 
-HTStore *
-LSUP_htstore_copy (const HTStore *src)
-{
-    HTStore *dest = LSUP_htstore_new (LSUP_htstore_size (src));
-    if (UNLIKELY (!dest)) return NULL;
-
-    if (UNLIKELY (LSUP_htstore_copy_contents (dest, src) < 0)) {
-        LSUP_htstore_free (dest);
-        return NULL;
-    }
-
-    return dest;
-}
-
-
+#if 0
 LSUP_rc
-LSUP_htstore_copy_contents (HTStore *dest, const HTStore *src)
+htstore_copy_contents (HTStore *dest, const HTStore *src)
 {
     size_t i = 0;
     LSUP_TripleKey *spok;
@@ -196,88 +195,39 @@ LSUP_htstore_copy_contents (HTStore *dest, const HTStore *src)
 
     return LSUP_OK;
 }
-
-
-HTStore *
-LSUP_htstore_bool_op(
-        const LSUP_bool_op op, const HTStore *s1, const HTStore *s2)
-{
-    if (UNLIKELY (
-            op != LSUP_BOOL_UNION
-            && op != LSUP_BOOL_SUBTRACTION
-            && op != LSUP_BOOL_INTERSECTION
-            && op != LSUP_BOOL_XOR)) {
-        log_error ("Invalid boolean operation.");
-
-        return NULL;
-    }
-
-    HTStore *dest = LSUP_htstore_new (0);
-
-    if (op == LSUP_BOOL_UNION) {
-        dest = LSUP_htstore_copy (s1);
-        if (UNLIKELY (!dest) || LSUP_htstore_copy_contents (dest, s2) < 0)
-            goto fail;
-
-        return dest;
-    }
-
-    LSUP_TripleKey *src_tkey;
-
-    LSUP_HTIterator *it = LSUP_htstore_add_init(dest);
-
-    size_t i = 0;
-    if (op == LSUP_BOOL_XOR) {
-        // Add triples from s2 if not found in s1.
-        while (hashmap_iter (s2->keys, &i, (void **) &src_tkey)) {
-            if (!hashmap_get (s1->keys, src_tkey))
-                htstore_add_key_iter (it, *src_tkey);
-        }
-    }
-
-    i = 0;
-    while (hashmap_iter (s1->keys, &i, (void **) &src_tkey)) {
-        // For XOR and subtraction, add if not found.
-        // For intersection, add if found.
-        if (
-            (op == LSUP_BOOL_INTERSECTION)
-            ^ (hashmap_get (s2->keys, src_tkey) == NULL)
-        )
-            htstore_add_key_iter (it, *src_tkey);
-    }
-    LSUP_htstore_add_done (it);
-
-    return dest;
-
-fail:
-    LSUP_htstore_free (dest);
-    return NULL;
-}
+#endif
 
 
 void
-LSUP_htstore_free (HTStore *ht)
+htstore_free (void *h)
 {
-    hashmap_free (ht->idx);
-    hashmap_free (ht->keys);
-    free (ht);
+    HTStore *store = h;
+    hashmap_free (store->idx);
+    hashmap_free (store->keys);
+    free (store);
 }
 
 
 size_t
-LSUP_htstore_size (const LSUP_HTStore *ht)
-{ return hashmap_count (ht->keys); }
+htstore_size (const void *h)
+{
+    const HTStore *store = h;
+    return hashmap_count (store->keys);
+}
 
 
 LSUP_rc
-LSUP_htstore_add_term (HTStore *store, const LSUP_Buffer *sterm)
+htstore_add_term (void *h, const LSUP_Buffer *sterm)
 {
+    HTStore *store = h;
     IndexEntry entry_s = {
         .key = LSUP_buffer_hash (sterm),
     };
     if (hashmap_get (store->idx, &entry_s)) return LSUP_NOACTION;
 
-    entry_s.sterm = LSUP_buffer_new (sterm->size, sterm->addr);
+    entry_s.data = malloc (sterm->size);
+    memcpy (entry_s.data, sterm->addr, sterm->size);
+    entry_s.size = sterm->size;
 
     log_trace ("Adding term key: %lx", entry_s.key);
     hashmap_set (store->idx, &entry_s);
@@ -287,21 +237,23 @@ LSUP_htstore_add_term (HTStore *store, const LSUP_Buffer *sterm)
 }
 
 
-LSUP_HTIterator *
-LSUP_htstore_add_init (HTStore *store)
+void *
+htstore_add_init (void *h, const LSUP_Buffer *_unused)
 {
+    (void) _unused;
     HTIterator *it;
     MALLOC_GUARD (it, NULL);
 
-    it->store = store;
+    it->store = h;
 
     return it;
 }
 
 
 LSUP_rc
-LSUP_htstore_add_iter (HTIterator *it, const LSUP_BufferTriple *sspo)
+htstore_add_iter (void *h, const LSUP_BufferTriple *sspo)
 {
+    HTIterator *it = h;
     LSUP_TripleKey spok = {
         LSUP_buffer_hash (sspo->s),
         LSUP_buffer_hash (sspo->p),
@@ -313,54 +265,27 @@ LSUP_htstore_add_iter (HTIterator *it, const LSUP_BufferTriple *sspo)
     if (rc != LSUP_OK) return rc;
 
     for (int i = 0; i < 3; i++)
-        LSUP_htstore_add_term (it->store, LSUP_btriple_pos (sspo, i));
+        htstore_add_term (it->store, LSUP_btriple_pos (sspo, i));
 
     return rc;
 }
 
 
-void
-LSUP_htstore_add_done (HTIterator *it)
-{ LSUP_htiter_free (it); }
-
-
 LSUP_rc
-LSUP_htstore_remove(
-        LSUP_HTStore *store, const LSUP_Buffer *ss, const LSUP_Buffer *sp,
-        const LSUP_Buffer *so,  size_t *ct_p)
+htstore_add_done (void *h)
 {
-    size_t ct;
-
-    LSUP_HTIterator *it = LSUP_htstore_lookup (store, ss, sp, so, &ct);
-    if (UNLIKELY (!it)) return LSUP_DB_ERR;
-
-    LSUP_rc rc;
-    if (ct == 0) {
-        rc = LSUP_NOACTION;
-        goto finally;
-    }
-
-    while (htiter_next_key (it) == LSUP_OK) {
-        log_trace (
-                "Deleting {%lx, %lx, %lx}.",
-                it->entry[0][0], it->entry[0][1], it->entry[0][2]);
-        hashmap_delete (store->keys, it->entry);
-        rc = LSUP_OK;
-        it->cur = 0; // Reset cursor, buckets are rearranged after deletion.
-    }
-
-finally:
-    LSUP_htiter_free (it);
-    if (ct_p) *ct_p = ct;
-
-    return rc;
+    free (h);
+    return LSUP_OK;
 }
 
 
-HTIterator *
-LSUP_htstore_lookup (HTStore *store, const LSUP_Buffer *ss,
-        const LSUP_Buffer *sp, const LSUP_Buffer *so, size_t *ct)
+void *
+htstore_lookup (
+        void *h,
+        const LSUP_Buffer *ss, const LSUP_Buffer *sp, const LSUP_Buffer *so,
+        const LSUP_Buffer *sc, size_t *ct)
 {
+    HTStore *store = h;
     HTIterator *it;
     CALLOC_GUARD (it, NULL);
 
@@ -423,9 +348,40 @@ LSUP_htstore_lookup (HTStore *store, const LSUP_Buffer *ss,
 }
 
 
-void
-LSUP_htiter_free (LSUP_HTIterator *it)
-{ free (it); }
+LSUP_rc
+htstore_remove(
+        void *h, const LSUP_Buffer *ss, const LSUP_Buffer *sp,
+        const LSUP_Buffer *so,  const LSUP_Buffer *_unused, size_t *ct_p)
+{
+    (void) _unused;
+    HTStore *store = h;
+    size_t ct;
+
+    HTIterator *it = htstore_lookup (store, ss, sp, so, NULL, &ct);
+    if (UNLIKELY (!it)) return LSUP_DB_ERR;
+
+    LSUP_rc rc;
+    if (ct == 0) {
+        rc = LSUP_NOACTION;
+        goto finally;
+    }
+
+    while (htiter_next_key (it) == LSUP_OK) {
+        log_trace (
+                "Deleting {%lx, %lx, %lx}.",
+                it->entry[0][0], it->entry[0][1], it->entry[0][2]);
+        hashmap_delete (store->keys, it->entry);
+        rc = LSUP_OK;
+        it->cur = 0; // Reset cursor, buckets are rearranged after deletion.
+    }
+
+finally:
+    free (it);
+    if (ct_p) *ct_p = ct;
+
+    return rc;
+}
+
 
 LSUP_rc
 htiter_next_key (HTIterator *it)
@@ -457,8 +413,10 @@ htiter_next_key (HTIterator *it)
 
 
 LSUP_rc
-LSUP_htiter_next (HTIterator *it, LSUP_BufferTriple *sspo)
+htiter_next (void *h, LSUP_BufferTriple *sspo, LSUP_Buffer **_unused)
 {
+    (void) _unused;
+    HTIterator *it = h;
     LSUP_rc rc = htiter_next_key (it);
     if (rc != LSUP_OK) return rc;
 
@@ -466,6 +424,29 @@ LSUP_htiter_next (HTIterator *it, LSUP_BufferTriple *sspo)
 }
 
 
+const LSUP_StoreInt htstore_int = {
+    .name           = "Hash Table Store",
+    .features       = LSUP_STORE_COW,
+
+    .setup_fn       = NULL,
+    .new_fn         = htstore_new,
+    .free_fn        = htstore_free,
+
+    .size_fn        = htstore_size,
+
+    .add_init_fn    = htstore_add_init,
+    .add_iter_fn    = htstore_add_iter,
+    .add_done_fn    = htstore_add_done,
+    .add_term_fn    = htstore_add_term,
+
+    .lookup_fn      = htstore_lookup,
+    .lu_next_fn     = htiter_next,
+    .lu_free_fn     = free,
+
+    .remove_fn      = htstore_remove,
+};
+
+
 /* * * Statics * * */
 
 inline static LSUP_rc
@@ -475,17 +456,12 @@ tkey_to_strp (
     // Data owned by the store.
     IndexEntry *tmp;
 
-    tmp = hashmap_get (store->idx, spok + 0);
-    if (UNLIKELY (!tmp)) return LSUP_DB_ERR;
-    sspo->s = tmp->sterm;
-
-    tmp = hashmap_get (store->idx, spok + 1);
-    if (UNLIKELY (!tmp)) return LSUP_DB_ERR;
-    sspo->p = tmp->sterm;
-
-    tmp = hashmap_get (store->idx, spok + 2);
-    if (UNLIKELY (!tmp)) return LSUP_DB_ERR;
-    sspo->o = tmp->sterm;
+    for (int i = 0; i < 3; i++) {
+        tmp = hashmap_get (store->idx, spok + i);
+        if (UNLIKELY (!tmp)) return LSUP_DB_ERR;
+        LSUP_btriple_pos(sspo, i)->addr = tmp->data;
+        LSUP_btriple_pos(sspo, i)->size = tmp->size;
+    }
 
     return LSUP_OK;
 }

src/store_mdb.c

@@ -1,7 +1,6 @@
 #include <ftw.h>
 
 #include "store_mdb.h"
-#include "data/bootstrap.h"
 
 /**
  * Number of DBs defined. See MAIN_TABLE and LOOKUP_TABLE defines below.
@@ -29,11 +28,11 @@
  */
 
 typedef char DbLabel[8];
+typedef struct mdbstore_iter_t MDBIterator;
 
 typedef enum {
-    LSSTORE_INIT         = 1, // Is the store environment set up on disk?
-    LSSTORE_OPEN         = 3, // Is the environment open? Assumes init is set.
-    LSSTORE_DIRTY_TXN    = 4, // Main txn was opened in a subroutine.
+    LSSTORE_OPEN         = 1<<0,                    ///< Env is open.
+    LSSTORE_DIRTY_TXN    = LSSTORE_OPEN + (1<<1),   ///< Main txn is open.
 } StoreState;
 
 typedef enum {
@@ -42,12 +41,11 @@ typedef enum {
 } StoreOp;
 
 typedef struct mdbstore_t {
-    MDB_env *           env;            // Environment handle.
-    MDB_txn *           txn;            // Current transaction.
-    MDB_dbi             dbi[N_DB];      // DB handles. Refer to DbIdx enum.
-    LSUP_Buffer *       default_ctx;    // Default ctx as a serialized URI.
-    StoreState          state;          // Store state.
-    int                 features;       // Store feature flags.
+    MDB_env *           env;            ///< Environment handle.
+    MDB_txn *           txn;            ///< Current transaction.
+    MDB_dbi             dbi[N_DB];      ///< DB handles. Refer to DbIdx enum.
+    StoreState          state;          ///< Store state.
+    int                 features;       ///< Store feature flags.
 } MDBStore;
 
 /** @brief Iterator operation.
@@ -60,7 +58,7 @@ typedef struct mdbstore_t {
  * value for the next result. It is up to the caller to evaluate this value
  * and decide whether to call the function again.
  */
-typedef void (*iter_op_fn_t)(LSUP_MDBIterator *it);
+typedef void (*iter_op_fn_t)(MDBIterator *it);
 
 
 /// Triple iterator.
@@ -94,29 +92,29 @@ typedef struct mdbstore_iter_t {
 /**
  * Main DBs. These are the master information containers.
  *
- * Data columns are: identifier prefix, DB label, flags.
- *
  * The number of entries must match the N_DB constant defined above.
  */
 #define MAIN_TABLE \
-    ENTRY(  T_ST,    "t:st",    0               )   /* Key to ser. term */  \
-    ENTRY(  SPO_C,   "spo:c",   DUPFIXED_MASK   )   /* Triple to context */ \
-    ENTRY(  C_,      "c:",      0               )   /* Track empty ctx */   \
-    ENTRY(  PFX_NS,  "pfx:ns",  0               )   /* Prefix to NS */      \
-    ENTRY(  IDK_ID,  "idk:id",  0               )   /* ID key to ID */      \
+/*          #ID pfx #DB label   #Flags  */ \
+    ENTRY(  T_ST,   "t:st",     0               )   /* Key to ser. term */  \
+    ENTRY(  SPO_C,  "spo:c",    DUPFIXED_MASK   )   /* Triple to context */ \
+    ENTRY(  C_,     "c:",       0               )   /* Track empty ctx */   \
+    ENTRY(  PFX_NS, "pfx:ns",   0               )   /* Prefix to NS */      \
+    ENTRY(  IDK_ID, "idk:id",   0               )   /* ID key to ID */      \
 
 /**
  * Lookup DBs. These are indices and may be destroyed and rebuilt.
  */
 #define LOOKUP_TABLE \
-    ENTRY(  S_PO,    "s:po",    DUPFIXED_MASK   )   /* 1-bound lookup */    \
-    ENTRY(  P_SO,    "p:so",    DUPFIXED_MASK   )   /* 1-bound lookup */    \
-    ENTRY(  O_SP,    "o:sp",    DUPFIXED_MASK   )   /* 1-bound lookup */    \
-    ENTRY(  PO_S,    "po:s",    DUPFIXED_MASK   )   /* 2-bound lookup */    \
-    ENTRY(  SO_P,    "so:p",    DUPFIXED_MASK   )   /* 2-bound lookup */    \
-    ENTRY(  SP_O,    "sp:o",    DUPFIXED_MASK   )   /* 2-bound lookup */    \
-    ENTRY(  C_SPO,   "c:spo",   DUPFIXED_MASK   )   /* Context lookup */    \
-    ENTRY(  NS_PFX,  "ns:pfx",  DUPSORT_MASK    )   /* NS to prefix */      \
+/*          #ID pfx #DB label  #Flags   */ \
+    ENTRY(  S_PO,    "s:po",   DUPFIXED_MASK    )   /* 1-bound lookup */    \
+    ENTRY(  P_SO,    "p:so",   DUPFIXED_MASK    )   /* 1-bound lookup */    \
+    ENTRY(  O_SP,    "o:sp",   DUPFIXED_MASK    )   /* 1-bound lookup */    \
+    ENTRY(  PO_S,    "po:s",   DUPFIXED_MASK    )   /* 2-bound lookup */    \
+    ENTRY(  SO_P,    "so:p",   DUPFIXED_MASK    )   /* 2-bound lookup */    \
+    ENTRY(  SP_O,    "sp:o",   DUPFIXED_MASK    )   /* 2-bound lookup */    \
+    ENTRY(  C_SPO,   "c:spo",  DUPFIXED_MASK    )   /* Context lookup */    \
+    ENTRY(  NS_PFX,  "ns:pfx", DUPSORT_MASK     )   /* NS to prefix */      \
 
 /**
  * DB labels. They are prefixed with DB_
@@ -188,7 +186,8 @@ static const uint8_t lookup_ordering_2bound[3][3] = {
  * Static prototypes.
  */
 static int index_triple(
-        LSUP_MDBStore *store, StoreOp op, LSUP_TripleKey spok, LSUP_Key ck);
+        MDBStore *store, StoreOp op, LSUP_TripleKey spok, LSUP_Key ck);
+static LSUP_rc mdbstore_add_term (void *h, const LSUP_Buffer *sterm);
 
 inline static LSUP_rc lookup_0bound (MDBIterator *it, size_t *ct);
 inline static LSUP_rc lookup_1bound (
@@ -199,66 +198,199 @@ inline static LSUP_rc lookup_3bound(MDBIterator *it, size_t *ct);
 
 
 /**
- * API.
+ * Store interface.
  */
 
+LSUP_NSMap *
+mdbstore_nsm_get (void *h)
+{
+    MDBStore *store = h;
+    LSUP_NSMap *nsm = LSUP_nsmap_new();
+    if (UNLIKELY (!nsm)) return NULL;
+
+    MDB_txn *txn;
+    mdb_txn_begin (store->env, NULL, MDB_RDONLY, &txn);
+
+    MDB_cursor *cur;
+    if (mdb_cursor_open (txn, store->dbi[IDX_PFX_NS], &cur) != MDB_SUCCESS) {
+        mdb_txn_abort (txn);
+        return NULL;
+    }
+
+    MDB_val ns_v, pfx_v;
+    if (mdb_cursor_get (cur, &pfx_v, &ns_v, MDB_FIRST) != MDB_SUCCESS)
+        goto finally;
+
+    do {
+        ns_pfx pfx;
+        char *ns = malloc (ns_v.mv_size);
+
+        strncpy (pfx, pfx_v.mv_data, pfx_v.mv_size);
+        strncpy (ns, ns_v.mv_data, ns_v.mv_size);
+        LSUP_nsmap_add (nsm, pfx, ns);
+
+        free (ns);
+    } while (mdb_cursor_get (
+                cur, &pfx_v, &ns_v, MDB_NEXT_NODUP) == MDB_SUCCESS);
+
+finally:
+    mdb_cursor_close (cur);
+    mdb_txn_abort (txn);
+
+    return nsm;
+}
+
+
 LSUP_rc
-LSUP_mdbstore_setup (const char *path, bool clear)
+mdbstore_nsm_put (void *h, const LSUP_NSMap *nsm)
 {
-    int rc;
+    MDBStore *store = h;
+    MDB_txn *txn;
+    RCCK (mdb_txn_begin (store->env, store->txn, 0, &txn));
+
+    LSUP_rc rc = LSUP_NOACTION;
+    int db_rc;
+
+    MDB_cursor *dcur = NULL, *icur = NULL;
+    if (
+        mdb_cursor_open (txn, store->dbi[IDX_PFX_NS], &dcur) != MDB_SUCCESS
+        ||
+        mdb_cursor_open (txn, store->dbi[IDX_NS_PFX], &icur) != MDB_SUCCESS
+    ) {
+        mdb_txn_abort (txn);
+        return LSUP_DB_ERR;
+    }
+
+    MDB_val pfx_v, ns_v;
+    const char ***nsm_data = LSUP_nsmap_dump (nsm);
+
+    for (size_t i = 0; nsm_data[i] != NULL; i++) {
+        // At least 1 action. If not OK, it will change during the iteration.
+        if (i == 0) rc = LSUP_OK;
+        // On previous error, just clean up the NSM data array.
+        if (rc < 0) goto loop_end;
+
+        pfx_v.mv_data = (void *) nsm_data[i][0];
+        pfx_v.mv_size = strlen (nsm_data[i][0]) + 1;
+        ns_v.mv_data = (void *) nsm_data[i][1];
+        ns_v.mv_size = strlen (nsm_data[i][1]) + 1;
 
+        // If either ns or pfx exist, skip.
+        if (
+            mdb_cursor_get (dcur, &pfx_v, &ns_v, MDB_SET) != MDB_NOTFOUND
+            ||
+            mdb_cursor_get (icur, &ns_v, &pfx_v, MDB_SET) != MDB_NOTFOUND
+        ) {
+            rc = LSUP_CONFLICT;
+            goto loop_end;
+        }
+
+        db_rc = mdb_cursor_put (dcur, &pfx_v, &ns_v, 0);
+        db_rc |= mdb_cursor_put (icur, &ns_v, &pfx_v, 0);
+        if (db_rc != MDB_SUCCESS) {
+            log_error ("DB error: %s", LSUP_strerror (db_rc));
+            rc = LSUP_DB_ERR;
+        }
+loop_end:
+        free (nsm_data[i]);
+    }
+    free (nsm_data);
+
+    if (UNLIKELY (rc != LSUP_OK)) mdb_txn_abort (txn);
+    else if (UNLIKELY (mdb_txn_commit (txn) != MDB_SUCCESS)) {
+        mdb_txn_abort (txn);
+        rc = LSUP_TXN_ERR;
+    }
+
+    return rc;
+}
+
+
+static const char *
+mdbstore_path_from_id (const char *id)
+{
     // Set environment path.
-    if (!path) {
-        log_error("Path %s does not exist.", path);
-        return LSUP_ERROR;
+    if (!id) id = getenv ("LSUP_MDB_STORE_URN");
+    if (!id) {
+        id = LSUP_MDB_STORE_URN;
+        log_info (
+            "`LSUP_MDB_STORE_URN' environment variable is not "
+            "set. The default URN %s has been set as the store ID.", id
+        );
     }
+    if (strncmp ("file://", id, 7) != 0) {
+        log_error ("MDB store ID must be in the `file://<abs_path>` format.");
+        return NULL;
+    }
+    return id + 7;
+}
+
 
-    // TODO Verify that a writable directory exists or can be created.
-    //struct stat path_stat;
+/** @brief Create the MDB environment and databases on disk.
+ *
+ * This function takes care of creaating the environment path if not existing,
+ * and checking that it's a writable directory. If the path is not specified
+ * in the LSUP_MDB_STORE_URN environment variable, a default directory is used.
+ */
+LSUP_rc
+mdbstore_setup (const char *id, bool clear)
+{
+    const char *path = mdbstore_path_from_id (id);
+    if (!path) return LSUP_VALUE_ERR;
 
+    // If the directory exists (unless clear == true), do nothing.
     if (clear) rm_r (path);
-    if (mkdir_p (path, ENV_DIR_MODE) != 0) return LSUP_IO_ERR;
+    LSUP_rc rc = mkdir_p (path, ENV_DIR_MODE);
+    log_info ("Create dir rc: %d", rc);
+    log_info ("LSUP Create dir rc: %d", rc);
+    RCCK (rc);
 
     // Open a temporary environment and txn to create the DBs.
     MDB_env *env;
-    mdb_env_create (&env);
+    RCCK (mdb_env_create (&env));
 
-    mdb_env_set_maxdbs (env, N_DB);
+    RCCK (mdb_env_set_maxdbs (env, N_DB));
     RCCK (mdb_env_open (env, path, 0, ENV_FILE_MODE));
     log_debug ("Environment opened at %s.", path);
 
     MDB_txn *txn;
-    mdb_txn_begin (env, NULL, 0, &txn);
+    RCCK (mdb_txn_begin (env, NULL, 0, &txn));
     for (int i = 0; i < N_DB; i++) {
         log_trace ("Creating DB %s", db_labels[i]);
         MDB_dbi dbi;
-        rc = mdb_dbi_open (txn, db_labels[i], db_flags[i] | MDB_CREATE, &dbi);
-        if (rc != MDB_SUCCESS) return rc;
+        RCCK (
+            mdb_dbi_open (txn, db_labels[i], db_flags[i] | MDB_CREATE, &dbi)
+        );
     }
 
     mdb_txn_commit (txn);
     mdb_env_close (env);
 
-    return rc;
+    return LSUP_OK;
 }
 
 
-MDBStore *
-LSUP_mdbstore_new (const char *path, const LSUP_Buffer *default_ctx)
+/** @brief Open an MDB store.
+ *
+ * The store must have been set up with #mdbstore_setup.
+ *
+ * Some environment variables affect various store parameters:
+ *
+ * - LSUP_MDB_MAPSIZE Long int specifying the size of the memory map. Usually
+ *   it is not necessary to modify this, unless one is operating under memory
+ *   and disk constraints. The default map size is 1Tb.
+ */
+void *
+mdbstore_new (const char *id, size_t _unused)
 {
-    int db_rc;
-    LSUP_MDBStore *store;
-    MALLOC_GUARD (store, NULL);
-    store->features = LSUP_STORE_CTX | LSUP_STORE_IDX;
-    if (strcmp (path, LSUP_MDB_RAMDISK_PATH) != 0)
-            store->features |= LSUP_STORE_PERM;
+    (void) _unused;
+    const char *path = mdbstore_path_from_id (id);
+    if (!path) return NULL;
 
-    db_rc = mdb_env_create (&store->env);
-    log_trace ("create rc: %d", db_rc);
+    MDBStore *store;
+    CALLOC_GUARD (store, NULL);
 
-    store->default_ctx = (
-            default_ctx ?
-            LSUP_buffer_new (default_ctx->size, default_ctx->addr) : NULL);
+    RCNL (mdb_env_create (&store->env));
 
     // Set map size.
     size_t mapsize;
@@ -268,40 +400,26 @@ LSUP_mdbstore_new (const char *path, const LSUP_Buffer *default_ctx)
     log_info (
             "Setting environment map size at %s to %lu Mb.",
             path, mapsize / 1024 / 1024);
-    db_rc = mdb_env_set_mapsize (store->env, mapsize);
-
-    db_rc = mdb_env_set_maxdbs (store->env, N_DB);
-    if (UNLIKELY (db_rc != MDB_SUCCESS)) return NULL;
-
-    db_rc = mdb_env_open (store->env, path, 0, ENV_FILE_MODE);
-    if (UNLIKELY (db_rc != MDB_SUCCESS)) return NULL;
+    CHECK (mdb_env_set_mapsize (store->env, mapsize), fail);
+    CHECK (mdb_env_set_maxdbs (store->env, N_DB), fail);
+    CHECK (mdb_env_open (store->env, path, 0, ENV_FILE_MODE), fail);
 
     // Assign DB handles to store->dbi.
     mdb_txn_begin (store->env, NULL, 0, &store->txn);
-    for (int i = 0; i < N_DB; i++) {
-        db_rc = mdb_dbi_open (
-                store->txn, db_labels[i], db_flags[i], store->dbi + i);
-        if (UNLIKELY (db_rc != MDB_SUCCESS)) goto fail;
-    }
-
-    if (store->features & LSUP_STORE_PERM) {
-        // Bootstrap the permanent store with initial data.
-        MDB_stat stat;
-        mdb_stat (store->txn, store->dbi[IDX_PFX_NS], &stat);
-
-        if (stat.ms_entries == 0) {
-            log_debug ("Loading initial data into %s", path);
-
-            // Load initial NS map.
-            LSUP_NSMap *nsm = LSUP_nsmap_new();
-
-            for (int i = 0; init_nsmap[i][0] != NULL; i++)
-                LSUP_nsmap_add (nsm, init_nsmap[i][0], init_nsmap[i][1]);
+    for (int i = 0; i < N_DB; i++)
+        CHECK (mdb_dbi_open (
+                store->txn, db_labels[i], db_flags[i], store->dbi + i), fail);
 
-            LSUP_mdbstore_nsm_store (store, nsm);
-
-            LSUP_nsmap_free (nsm);
-        }
+    // Bootstrap the permanent store with initial data.
+    MDB_stat stat;
+    CHECK (mdb_stat (store->txn, store->dbi[IDX_PFX_NS], &stat), fail);
+    if (stat.ms_entries == 0) {
+        log_debug ("Loading initial data into %s", path);
+        // Load initial NS map.
+        mdbstore_nsm_put (store, LSUP_default_nsm);
+
+        // Index default context.
+        mdbstore_add_term (store, LSUP_default_ctx_buf);
     }
 
     store->state |= LSSTORE_OPEN;
@@ -311,15 +429,17 @@ LSUP_mdbstore_new (const char *path, const LSUP_Buffer *default_ctx)
     return store;
 
 fail:
-    log_error (LSUP_strerror (db_rc));
     if (store->txn) mdb_txn_abort (store->txn);
+    mdb_env_close (store->env);
+
     return NULL;
 }
 
 
 void
-LSUP_mdbstore_free (LSUP_MDBStore *store)
+mdbstore_free (void *h)
 {
+    MDBStore *store = h;
     if (store->state & LSSTORE_OPEN) {
         const char *path;
         mdb_env_get_path (store->env, &path);
@@ -327,23 +447,24 @@ LSUP_mdbstore_free (LSUP_MDBStore *store)
         mdb_env_close (store->env);
     }
 
-    if (store->default_ctx) {
-        LSUP_buffer_done (store->default_ctx);
-        free (store->default_ctx);
-    }
-
     free (store);
 }
 
 
-int LSUP_mdbstore_features (LSUP_MDBStore *store)
-{ return store->features; }
+char *mdbstore_id (const void *h)
+{
+    const MDBStore *store = h;
+    const char *path;
+    mdb_env_get_path (store->env, &path);
+
+    return strcat ("file://", path);
+}
 
 
 LSUP_rc
-LSUP_mdbstore_stat (LSUP_MDBStore *store, MDB_stat *stat)
+mdbstore_stat (const MDBStore *store, MDB_stat *stat)
 {
-    if (!(store->state & LSSTORE_INIT)) return 0;
+    if (!(store->state & LSSTORE_OPEN)) return 0;
 
     MDB_txn *txn;
     mdb_txn_begin (store->env, NULL, MDB_RDONLY, &txn);
@@ -357,20 +478,22 @@ LSUP_mdbstore_stat (LSUP_MDBStore *store, MDB_stat *stat)
 
 
 size_t
-LSUP_mdbstore_size (LSUP_MDBStore *store)
+mdbstore_size (const void *h)
 {
+    const MDBStore *store = h;
     // Size is calculated outside of any pending write txn.
 
     MDB_stat stat;
-    if (LSUP_mdbstore_stat (store, &stat) != LSUP_OK) return 0;
+    if (mdbstore_stat (store, &stat) != LSUP_OK) return 0;
 
     return stat.ms_entries;
 }
 
 
-MDBIterator *
-LSUP_mdbstore_add_init (LSUP_MDBStore *store, const LSUP_Buffer *sc)
+void *
+mdbstore_add_init (void *h, const LSUP_Buffer *sc)
 {
+    MDBStore *store = h;
     /* An iterator is used here. Some members are a bit misused but it does
      * its job without having to define a very similar struct.
      */
@@ -387,13 +510,8 @@ LSUP_mdbstore_add_init (LSUP_MDBStore *store, const LSUP_Buffer *sc)
     }
     mdb_txn_begin (store->env, NULL, 0, &it->store->txn);
 
-    // Take care of context first.
-    // Serialize and hash.
-    it->luc = NULL_KEY;
-
-    if (store->default_ctx != NULL) {
-        if (sc == NULL) sc = store->default_ctx;
-
+    if (sc) {
+        // Store context if it's not the default one.
         it->luc = LSUP_buffer_hash (sc);
 
         // Insert t:st for context.
@@ -403,23 +521,39 @@ LSUP_mdbstore_add_init (LSUP_MDBStore *store, const LSUP_Buffer *sc)
         it->data.mv_data = sc->addr;
         it->data.mv_size = sc->size;
 
-        if (mdb_put(
+        int db_rc = mdb_put(
                 it->store->txn, it->store->dbi[IDX_T_ST],
-                &it->key, &it->data, MDB_NOOVERWRITE) != MDB_SUCCESS)
+                &it->key, &it->data, MDB_NOOVERWRITE);
+        if (db_rc != MDB_SUCCESS && db_rc != MDB_KEYEXIST) {
+            LOG_RC (db_rc);
+            mdb_txn_abort (it->store->txn);
             return NULL;
+        }
+    } else {
+        log_debug ("No context passed to iterator, using default.");
+        it->luc = LSUP_buffer_hash (LSUP_default_ctx_buf);
     }
 
     return it;
 }
 
 
+/*
+ * NOTE: at the moment #mdbstore_remove() or another
+ * #mdbstore_init() cannot be called between #mdbstore_add_init and
+ * #mdbstore_add_abort or #mdbstore_add_done. FIXME
+ *
+ */
 LSUP_rc
-LSUP_mdbstore_add_iter (MDBIterator *it, const LSUP_BufferTriple *sspo)
+mdbstore_add_iter (void *h, const LSUP_BufferTriple *sspo)
 {
-    int db_rc;
+    if (UNLIKELY (!h)) return LSUP_VALUE_ERR;
+
+    MDBIterator *it = h;
+    int db_rc = LSUP_NOACTION;
     LSUP_TripleKey spok = NULL_TRP;
 
-    // Add triple.
+    // Add triple terms.
     for (int i = 0; i < 3; i++) {
         LSUP_Buffer *st = LSUP_btriple_pos (sspo, i);
 
@@ -434,9 +568,7 @@ LSUP_mdbstore_add_iter (MDBIterator *it, const LSUP_BufferTriple *sspo)
                 it->store->txn, it->store->dbi[IDX_T_ST],
                 &it->key, &it->data, MDB_NOOVERWRITE);
         if (db_rc != MDB_SUCCESS && db_rc != MDB_KEYEXIST) {
-            log_error (
-                    "MDB error while inserting term: %s",
-                    LSUP_strerror(db_rc));
+            LOG_RC (db_rc);
             return LSUP_DB_ERR;
         }
     }
@@ -472,8 +604,9 @@ LSUP_mdbstore_add_iter (MDBIterator *it, const LSUP_BufferTriple *sspo)
 
 
 LSUP_rc
-LSUP_mdbstore_add_done (MDBIterator *it)
+mdbstore_add_done (void *h)
 {
+    MDBIterator *it = h;
     LSUP_rc rc = LSUP_OK;
 
     if (mdb_txn_commit (it->store->txn) != MDB_SUCCESS) {
@@ -490,8 +623,9 @@ LSUP_mdbstore_add_done (MDBIterator *it)
 
 
 void
-LSUP_mdbstore_add_abort (MDBIterator *it)
+mdbstore_add_abort (void *h)
 {
+    MDBIterator *it = h;
     mdb_txn_abort (it->store->txn);
 
     it->store->txn = NULL;
@@ -500,29 +634,31 @@ LSUP_mdbstore_add_abort (MDBIterator *it)
 }
 
 
+/* TODO deprecate. Use low-level instead and abstract at graph level. */
 LSUP_rc
-LSUP_mdbstore_add (
-        LSUP_MDBStore *store, const LSUP_Buffer *sc,
+mdbstore_add (
+        void *h, const LSUP_Buffer *sc,
         const LSUP_BufferTriple strp[], const size_t ct, size_t *inserted)
 {
-    MDBIterator *it = LSUP_mdbstore_add_init (store, sc);
+    MDBStore *store = h;
+    MDBIterator *it = mdbstore_add_init (store, sc);
     if (UNLIKELY (!it)) return LSUP_DB_ERR;
 
     for (size_t i = 0; i < ct; i++) {
-        LSUP_rc rc = LSUP_mdbstore_add_iter (it, strp + i);
+        LSUP_rc rc = mdbstore_add_iter (it, strp + i);
         if (UNLIKELY (rc < 0)) {
-            LSUP_mdbstore_add_abort (it);
+            mdbstore_add_abort (it);
             return rc;
         }
     }
     *inserted = it->i;
 
-    return LSUP_mdbstore_add_done (it);
+    return mdbstore_add_done (it);
 }
 
 
 static LSUP_rc
-key_to_sterm (LSUP_MDBIterator *it, const LSUP_Key key, LSUP_Buffer *sterm)
+key_to_sterm (MDBIterator *it, const LSUP_Key key, LSUP_Buffer *sterm)
 {
     LSUP_rc rc = LSUP_NORESULT;
     int db_rc;
@@ -546,22 +682,23 @@ key_to_sterm (LSUP_MDBIterator *it, const LSUP_Key key, LSUP_Buffer *sterm)
 }
 
 
-MDBIterator *
-LSUP_mdbstore_lookup(
-        LSUP_MDBStore *store, const LSUP_Buffer *ss, const LSUP_Buffer *sp,
+void *
+mdbstore_lookup (
+        void *h, const LSUP_Buffer *ss, const LSUP_Buffer *sp,
         const LSUP_Buffer *so, const LSUP_Buffer *sc, size_t *ct)
 {
+    MDBStore *store = h;
     LSUP_TripleKey spok = {
         LSUP_buffer_hash (ss),
         LSUP_buffer_hash (sp),
         LSUP_buffer_hash (so),
     };
 
-    LSUP_MDBIterator *it;
+    MDBIterator *it;
     CALLOC_GUARD (it, NULL);
 
     it->store = store;
-    it->luc = store->default_ctx ? LSUP_buffer_hash (sc) : NULL_KEY;
+    it->luc = LSUP_buffer_hash (sc);
     log_debug ("Lookup context: %lx", it->luc);
 
     if (ct) *ct = 0;
@@ -591,7 +728,7 @@ LSUP_mdbstore_lookup(
         it->luk[0] = spok[0];
         it->luk[1] = spok[1];
         it->luk[2] = spok[2];
-        RCNL (lookup_3bound (it, ct));
+        PRCNL (lookup_3bound (it, ct));
 
     } else if (spok[0] != NULL_KEY) {
         it->luk[0] = spok[0];
@@ -601,16 +738,16 @@ LSUP_mdbstore_lookup(
         if (spok[1] != NULL_KEY) {
             it->luk[1] = spok[1];
             idx1 = 1;
-            RCNL (lookup_2bound (idx0, idx1, it, ct));
+            PRCNL (lookup_2bound (idx0, idx1, it, ct));
 
         // s ? o
         } else if (spok[2] != NULL_KEY) {
             it->luk[1] = spok[2];
             idx1 = 2;
-            RCNL (lookup_2bound (idx0, idx1, it, ct));
+            PRCNL (lookup_2bound (idx0, idx1, it, ct));
 
         // s ? ?
-        } else RCNL (lookup_1bound (idx0, it, ct));
+        } else PRCNL (lookup_1bound (idx0, it, ct));
 
     } else if (spok[1] != NULL_KEY) {
         it->luk[0] = spok[1];
@@ -620,19 +757,19 @@ LSUP_mdbstore_lookup(
         if (spok[2] != NULL_KEY) {
             it->luk[1] = spok[2];
             idx1 = 2;
-            RCNL (lookup_2bound (idx0, idx1, it, ct));
+            PRCNL (lookup_2bound (idx0, idx1, it, ct));
 
         // ? p ?
-        } else RCNL (lookup_1bound (idx0, it, ct));
+        } else PRCNL (lookup_1bound (idx0, it, ct));
 
     // ? ? o
     } else if (spok[2] != NULL_KEY) {
         it->luk[0] = spok[2];
         idx0 = 2;
-        RCNL (lookup_1bound (idx0, it, ct));
+        PRCNL (lookup_1bound (idx0, it, ct));
 
     // ? ? ? (all terms unbound)
-    } else RCNL (lookup_0bound (it, ct));
+    } else PRCNL (lookup_0bound (it, ct));
 
     return it;
 }
@@ -644,7 +781,7 @@ LSUP_mdbstore_lookup(
  * in, if not NULL.
  */
 inline static LSUP_rc
-mdbiter_next_key (LSUP_MDBIterator *it)
+mdbiter_next_key (MDBIterator *it)
 {
     if (UNLIKELY (!it)) return LSUP_VALUE_ERR;
 
@@ -736,9 +873,10 @@ mdbiter_next_key (LSUP_MDBIterator *it)
 
 
 LSUP_rc
-LSUP_mdbiter_next (
-        LSUP_MDBIterator *it, LSUP_BufferTriple *sspo, LSUP_Buffer **ctx_p)
+mdbiter_next (
+        void *h, LSUP_BufferTriple *sspo, LSUP_Buffer **ctx_p)
 {
+    MDBIterator *it = h;
     LSUP_rc rc = mdbiter_next_key (it);
 
     if (rc == LSUP_OK) {
@@ -774,8 +912,9 @@ LSUP_mdbiter_next (
 
 
 void
-LSUP_mdbiter_free (MDBIterator *it)
+mdbiter_free (void *h)
 {
+    MDBIterator *it = h;
     if (!it) return;
 
     if (it->cur) mdb_cursor_close (it->cur);
@@ -788,18 +927,17 @@ LSUP_mdbiter_free (MDBIterator *it)
 
 
 LSUP_rc
-LSUP_mdbstore_remove(
-        LSUP_MDBStore *store, const LSUP_Buffer *ss, const LSUP_Buffer *sp,
+mdbstore_remove(
+        void *h, const LSUP_Buffer *ss, const LSUP_Buffer *sp,
         const LSUP_Buffer *so, const LSUP_Buffer *sc, size_t *ct)
 {
+    MDBStore *store = h;
     LSUP_rc rc = LSUP_NOACTION, db_rc;
 
     LSUP_Key ck = NULL_KEY;
 
-    if (store->default_ctx != NULL) {
-        if (sc == NULL) sc = store->default_ctx;
-        ck = LSUP_buffer_hash (sc);
-    }
+    if (sc == NULL) sc = LSUP_default_ctx_buf;
+    ck = LSUP_buffer_hash (sc);
 
     // No other write transaction may be open.
     if (UNLIKELY (store->txn)) return LSUP_TXN_ERR;
@@ -815,7 +953,7 @@ LSUP_mdbstore_remove(
     ck_v.mv_size = KLEN;
     ck_v.mv_data = &ck;
 
-    LSUP_MDBIterator *it = LSUP_mdbstore_lookup (store, ss, sp, so, sc, ct);
+    MDBIterator *it = mdbstore_lookup (store, ss, sp, so, sc, ct);
     if (UNLIKELY (!it)) return LSUP_DB_ERR;
     if (ct) log_debug ("Found %lu triples to remove.", *ct);
 
@@ -858,7 +996,7 @@ LSUP_mdbstore_remove(
         rc = index_triple (store, OP_REMOVE, it->spok, ck);
     }
 
-    LSUP_mdbiter_free (it);
+    mdbiter_free (it);
 
     if (UNLIKELY (mdb_txn_commit (store->txn) != MDB_SUCCESS)) {
         rc = LSUP_TXN_ERR;
@@ -878,114 +1016,8 @@ fail:
 }
 
 
-LSUP_rc
-LSUP_mdbstore_nsm_get (LSUP_MDBStore *store, LSUP_NSMap **nsm_p)
-{
-    LSUP_rc rc = LSUP_NORESULT;
-    LSUP_NSMap *nsm = LSUP_nsmap_new();
-    if (UNLIKELY (!nsm)) return LSUP_MEM_ERR;
-
-    *nsm_p = nsm;
-
-    MDB_txn *txn;
-    mdb_txn_begin (store->env, NULL, MDB_RDONLY, &txn);
-
-    MDB_cursor *cur;
-    if (mdb_cursor_open (txn, store->dbi[IDX_PFX_NS], &cur) != MDB_SUCCESS) {
-        mdb_txn_abort (txn);
-        return LSUP_DB_ERR;
-    }
-
-    MDB_val ns_v, pfx_v;
-    if (mdb_cursor_get (cur, &pfx_v, &ns_v, MDB_FIRST) != MDB_SUCCESS)
-        goto finally;
-
-    do {
-        ns_pfx pfx;
-        char *ns = malloc (ns_v.mv_size);
-
-        strncpy (pfx, pfx_v.mv_data, pfx_v.mv_size);
-        strncpy (ns, ns_v.mv_data, ns_v.mv_size);
-        LSUP_nsmap_add (nsm, pfx, ns);
-
-        free (ns);
-    } while (mdb_cursor_get (
-                cur, &pfx_v, &ns_v, MDB_NEXT_NODUP) == MDB_SUCCESS);
-
-finally:
-    mdb_cursor_close (cur);
-    mdb_txn_abort (txn);
-
-    return rc;
-}
-
-
-LSUP_rc
-LSUP_mdbstore_nsm_store (LSUP_MDBStore *store, const LSUP_NSMap *nsm)
-{
-    MDB_txn *txn;
-    RCCK (mdb_txn_begin (store->env, store->txn, 0, &txn));
-
-    LSUP_rc rc = LSUP_NOACTION;
-    int db_rc;
-
-    MDB_cursor *dcur = NULL, *icur = NULL;
-    if (
-        mdb_cursor_open (txn, store->dbi[IDX_PFX_NS], &dcur) != MDB_SUCCESS
-        ||
-        mdb_cursor_open (txn, store->dbi[IDX_NS_PFX], &icur) != MDB_SUCCESS
-    ) {
-        mdb_txn_abort (txn);
-        return LSUP_DB_ERR;
-    }
-
-    MDB_val pfx_v, ns_v;
-    const char ***nsm_data = LSUP_nsmap_dump (nsm);
-
-    for (size_t i = 0; nsm_data[i] != NULL; i++) {
-        // At least 1 action. If not OK, it will change during the iteration.
-        if (i == 0) rc = LSUP_OK;
-        // On previous error, just clean up the NSM data array.
-        if (rc < 0) goto loop_end;
-
-        pfx_v.mv_data = (void *) nsm_data[i][0];
-        pfx_v.mv_size = strlen (nsm_data[i][0]) + 1;
-        ns_v.mv_data = (void *) nsm_data[i][1];
-        ns_v.mv_size = strlen (nsm_data[i][1]) + 1;
-
-        // If either ns or pfx exist, skip.
-        if (
-            mdb_cursor_get (dcur, &pfx_v, &ns_v, MDB_SET) != MDB_NOTFOUND
-            ||
-            mdb_cursor_get (icur, &ns_v, &pfx_v, MDB_SET) != MDB_NOTFOUND
-        ) {
-            rc = LSUP_CONFLICT;
-            goto loop_end;
-        }
-
-        db_rc = mdb_cursor_put (dcur, &pfx_v, &ns_v, 0);
-        db_rc |= mdb_cursor_put (icur, &ns_v, &pfx_v, 0);
-        if (db_rc != MDB_SUCCESS) {
-            log_error ("DB error: %s", LSUP_strerror (db_rc));
-            rc = LSUP_DB_ERR;
-        }
-loop_end:
-        free (nsm_data[i]);
-    }
-    free (nsm_data);
-
-    if (UNLIKELY (rc != LSUP_OK)) mdb_txn_abort (txn);
-    else if (UNLIKELY (mdb_txn_commit (txn) != MDB_SUCCESS)) {
-        mdb_txn_abort (txn);
-        rc = LSUP_TXN_ERR;
-    }
-
-    return rc;
-}
-
-
 int
-LSUP_mdbstore_tkey_exists (LSUP_MDBStore *store, LSUP_Key tkey)
+mdbstore_tkey_exists (MDBStore *store, LSUP_Key tkey)
 {
     int db_rc, rc;
     MDB_val key, data;
@@ -1014,9 +1046,10 @@ LSUP_mdbstore_tkey_exists (LSUP_MDBStore *store, LSUP_Key tkey)
 }
 
 
-LSUP_rc
-LSUP_mdbstore_add_term (LSUP_MDBStore *store, const LSUP_Buffer *sterm)
+static LSUP_rc
+mdbstore_add_term (void *h, const LSUP_Buffer *sterm)
 {
+    MDBStore *store = h;
     int db_rc;
     MDB_val key, data;
 
@@ -1036,12 +1069,12 @@ LSUP_mdbstore_add_term (LSUP_MDBStore *store, const LSUP_Buffer *sterm)
     data.mv_size = sterm->size;
 
     db_rc = mdb_cursor_put (cur, &key, &data, MDB_NOOVERWRITE);
-    if (db_rc != MDB_SUCCESS && db_rc != MDB_KEYEXIST) goto fail;
+    if (db_rc != MDB_KEYEXIST) CHECK (db_rc, fail);
 
     if (txn != store->txn) {
         db_rc = mdb_txn_commit (txn);
         txn = NULL;
-        if (UNLIKELY (db_rc != MDB_SUCCESS)) goto fail;
+        CHECK (db_rc, fail);
     }
 
     return LSUP_OK;
@@ -1053,8 +1086,35 @@ fail:
 }
 
 
-/* * * Static functions. * * */
+const LSUP_StoreInt mdbstore_int = {
+    .name           = "MDB Store",
+    .features       = LSUP_STORE_PERM | LSUP_STORE_CTX | LSUP_STORE_IDX
+                      | LSUP_STORE_TXN | LSUP_STORE_COW,
+
+    .setup_fn       = mdbstore_setup,
+    .new_fn         = mdbstore_new,
+    .free_fn        = mdbstore_free,
 
+    .size_fn        = mdbstore_size,
+
+    .add_init_fn    = mdbstore_add_init,
+    .add_iter_fn    = mdbstore_add_iter,
+    .add_abort_fn   = mdbstore_add_abort,
+    .add_done_fn    = mdbstore_add_done,
+    .add_term_fn    = mdbstore_add_term,
+
+    .lookup_fn      = mdbstore_lookup,
+    .lu_next_fn     = mdbiter_next,
+    .lu_free_fn     = mdbiter_free,
+
+    .remove_fn      = mdbstore_remove,
+
+    .nsm_put_fn     = mdbstore_nsm_put,
+    .nsm_get_fn     = mdbstore_nsm_get,
+};
+
+
+/* * * Static functions. * * */
 
 /** @brief Index an added or removed triple.
  *
@@ -1064,14 +1124,13 @@ fail:
  * @param ck[in] Context to index, may be NULL.
  */
 static LSUP_rc
-index_triple(
-        LSUP_MDBStore *store, StoreOp op, LSUP_TripleKey spok, LSUP_Key ck)
+index_triple(MDBStore *store, StoreOp op, LSUP_TripleKey spok, LSUP_Key ck)
 {
     int db_rc;
     LSUP_rc rc = LSUP_NOACTION;
     MDB_val v1, v2;
 
-    log_trace ("Indexing triple: %lx %lx %lx", spok[0], spok[1], spok[2]);
+    log_trace ("Indexing triple: {%lx %lx %lx}", spok[0], spok[1], spok[2]);
 
     // Index c:spo.
     if (op == OP_REMOVE) {

test.c

@@ -3,8 +3,7 @@
 #include "test_term.c"
 #include "test_namespace.c"
 #include "test_codec_nt.c"
-#include "test_store_ht.c"
-#include "test_store_mdb.c"
+#include "test_store.c"
 #include "test_graph.c"
 
 #define TEST_STORE_PATH TMPDIR "/lsup_test_mdb"
@@ -27,8 +26,7 @@ int main(int argc, char **argv) {
     if (
         term_tests() ||
         namespace_tests() ||
-        store_ht_tests() ||
-        store_mdb_tests() ||
+        store_tests() ||
         graph_tests() ||
         codec_nt_tests() ||
         0

test/cpython_test.py

@@ -67,13 +67,13 @@ class TestTerm(unittest.TestCase):
         self.assertFalse(hasattr(bn, 'lang'))
 
     def test_graph(self):
-        gr = graph.Graph(graph.STORE_MEM)
+        gr = graph.Graph(graph.STORE_HTABLE)
         gr.uri = term.Term(term.TERM_IRIREF, 'urn:c:1')
 
         self.assertEqual(gr.uri, 'urn:c:1')
 
     def test_graph_ops(self):
-        gr = graph.Graph(graph.STORE_MEM)
+        gr = graph.Graph(graph.STORE_HTABLE)
 
         print('Adding triples.')
         gr.add(self.trp)

test/test.h

@@ -47,11 +47,11 @@
 } while (0)
 
 #define EXPECT_PASS(exp) do { \
-    int rc = (exp); \
-    if (rc != LSUP_OK) {\
+    int _rc = (exp); \
+    if (_rc != LSUP_OK) {\
         fprintf(\
                 stderr, "!!! Test failed at %s:%d. Error: %s (%d)\n",\
-                __FILE__, __LINE__, LSUP_strerror(rc), rc); \
+                __FILE__, __LINE__, LSUP_strerror(_rc), _rc); \
         return -1; \
     }\
 } while (0)

test/test_codec_nt.c

@@ -161,7 +161,7 @@ test_encode_nt_term()
 static int test_encode_nt_graph()
 {
     LSUP_Graph *gr = LSUP_graph_new (
-            LSUP_iriref_new (NULL, NULL), LSUP_STORE_MEM);
+            LSUP_iriref_new (NULL, NULL), LSUP_STORE_HTABLE, NULL, NULL, 0);
     if (!gr) return LSUP_MEM_ERR;
 
     size_t ins;

test/test_graph.c

@@ -5,14 +5,22 @@
 #define N_LUT 13
 
 static int
-_graph_new (LSUP_store_type type)
+_graph_new (LSUP_StoreType type)
 {
-    LSUP_Graph *gr = LSUP_graph_new (LSUP_iriref_new (NULL, NULL), type);
+    const LSUP_StoreInt *sif = LSUP_store_int (type);
+    if (sif->setup_fn) sif->setup_fn (NULL, true);
+
+    LSUP_Graph *gr = LSUP_graph_new (
+            LSUP_iriref_new (NULL, NULL), type, NULL, NULL, 0);
     ASSERT (gr != NULL, "Error creating graph!");
 
     EXPECT_PASS (LSUP_graph_set_uri (gr, LSUP_iriref_new ("urn:gr:1", NULL)));
     EXPECT_STR_EQ (LSUP_graph_uri (gr)->data, "urn:gr:1");
 
+    // Check that setup function is idempotent with clear == false.
+    if (sif->setup_fn) EXPECT_INT_EQ (
+            sif->setup_fn (NULL, false), LSUP_NOACTION);
+
     ASSERT (
             strcmp (LSUP_graph_uri (gr)->data, "urn:gr:1") == 0,
             "Graph URI mismatch!");
@@ -25,11 +33,15 @@ _graph_new (LSUP_store_type type)
 
 
 static int
-_graph_add (LSUP_store_type type)
+_graph_add (LSUP_StoreType type)
 {
+    const LSUP_StoreInt *sif = LSUP_store_int (type);
+    if (sif->setup_fn) sif->setup_fn (NULL, true);
+
     LSUP_Triple *trp = create_triples();
 
-    LSUP_Graph *gr = LSUP_graph_new (LSUP_iriref_new (NULL, NULL), type);
+    LSUP_Graph *gr = LSUP_graph_new (
+            LSUP_iriref_new (NULL, NULL), type, NULL, NULL, 0);
     ASSERT (gr != NULL, "Error creating graph!");
 
     size_t ct;
@@ -56,8 +68,9 @@ _graph_add (LSUP_store_type type)
 
 
 static int
-_graph_lookup (LSUP_store_type type)
+_graph_lookup (LSUP_StoreType type)
 {
+    const LSUP_StoreInt *sif = LSUP_store_int (type);
     LSUP_Triple *trp = create_triples();
 
     // Lookup triples.
@@ -106,7 +119,10 @@ _graph_lookup (LSUP_store_type type)
     };
     */
 
-    LSUP_Graph *gr = LSUP_graph_new (LSUP_iriref_new (NULL, NULL), type);
+    if (sif->setup_fn) sif->setup_fn (NULL, true);
+
+    LSUP_Graph *gr = LSUP_graph_new (
+            LSUP_iriref_new (NULL, NULL), type, NULL, NULL, 0);
 
     size_t ct;
     LSUP_graph_add (gr, trp, &ct);
@@ -118,8 +134,7 @@ _graph_lookup (LSUP_store_type type)
         log_info ("Checking triple #%d on %d.", i, type);
         LSUP_GraphIterator *it = LSUP_graph_lookup (
                 gr, lu_trp[i][0], lu_trp[i][1], lu_trp[i][2], &ct);
-        if (type != LSUP_STORE_MEM) // TODO not implemented in htable.
-            EXPECT_INT_EQ (ct, lu_ct[i]);
+        EXPECT_INT_EQ (ct, lu_ct[i]);
 
         /* TODO
         for (int j = 0; j < 8; j++) {
@@ -145,11 +160,15 @@ _graph_lookup (LSUP_store_type type)
 
 
 static int
-_graph_remove (LSUP_store_type type)
+_graph_remove (LSUP_StoreType type)
 {
+    const LSUP_StoreInt *sif = LSUP_store_int (type);
+    if (sif->setup_fn) sif->setup_fn (NULL, true);
+
     LSUP_Triple *trp = create_triples();
 
-    LSUP_Graph *gr = LSUP_graph_new (LSUP_iriref_new (NULL, NULL), type);
+    LSUP_Graph *gr = LSUP_graph_new (
+            LSUP_iriref_new (NULL, NULL), type, NULL, NULL, 0);
 
     size_t ct;
     LSUP_graph_add (gr, trp, &ct);
@@ -186,51 +205,60 @@ static int
 test_environment()
 {
     // The env should already be initialized and re-initializing it is idempotent.
-    ASSERT (LSUP_init() > 0, "Environment not initialized!");
-    EXPECT_INT_EQ (LSUP_env_is_init, true);
+    EXPECT_INT_EQ (LSUP_IS_INIT, true);
+    ASSERT (LSUP_init() > 0, "Error initializing environment!");
+    EXPECT_INT_EQ (LSUP_IS_INIT, true);
 
     // Tearing down is idempotent too.
     LSUP_done();
-    EXPECT_INT_EQ (LSUP_env_is_init, false);
+    EXPECT_INT_EQ (LSUP_IS_INIT, false);
     LSUP_done();
-    EXPECT_INT_EQ (LSUP_env_is_init, false);
+    EXPECT_INT_EQ (LSUP_IS_INIT, false);
 
     ASSERT (LSUP_init() >= 0, "Environment not initialized!");
-    EXPECT_INT_EQ (LSUP_env_is_init, true);
+    EXPECT_INT_EQ (LSUP_IS_INIT, true);
     ASSERT (LSUP_init() >= 0, "Environment not initialized!");
-    EXPECT_INT_EQ (LSUP_env_is_init, true);
+    EXPECT_INT_EQ (LSUP_IS_INIT, true);
 
     return 0;
 }
 
 
 static int test_graph_new() {
-    if (_graph_new (LSUP_STORE_MEM) != 0) return -1;
-    if (_graph_new (LSUP_STORE_MDB_TMP) != 0) return -1;
+#define ENTRY(a, b) \
+    if (_graph_new (LSUP_STORE_##a) != 0) return -1;
+BACKEND_TBL
+#undef ENTRY
 
     return 0;
 }
 
 
 static int test_graph_add() {
-    if (_graph_add (LSUP_STORE_MEM) != 0) return -1;
-    if (_graph_add (LSUP_STORE_MDB_TMP) != 0) return -1;
+#define ENTRY(a, b) \
+    if (_graph_add (LSUP_STORE_##a) != 0) return -1;
+BACKEND_TBL
+#undef ENTRY
 
     return 0;
 }
 
 
 static int test_graph_lookup() {
-    if (_graph_lookup (LSUP_STORE_MEM) != 0) return -1;
-    if (_graph_lookup (LSUP_STORE_MDB_TMP) != 0) return -1;
+#define ENTRY(a, b) \
+    if (_graph_lookup (LSUP_STORE_##a) != 0) return -1;
+BACKEND_TBL
+#undef ENTRY
 
     return 0;
 }
 
 
 static int test_graph_remove() {
-    if (_graph_remove (LSUP_STORE_MEM) != 0) return -1;
-    if (_graph_remove (LSUP_STORE_MDB_TMP) != 0) return -1;
+#define ENTRY(a, b) \
+    if (_graph_remove (LSUP_STORE_##a) != 0) return -1;
+BACKEND_TBL
+#undef ENTRY
 
     return 0;
 }
@@ -241,13 +269,16 @@ static int test_graph_copy()
     LSUP_Triple *trp = create_triples();
 
     LSUP_Graph *gr1 = LSUP_graph_new (
-            LSUP_iriref_new (NULL, NULL), LSUP_STORE_MEM);
+            LSUP_iriref_new (NULL, NULL), LSUP_STORE_HTABLE, NULL, NULL, 0);
     ASSERT (gr1 != NULL, "Error creating graph!");
 
     LSUP_graph_add (gr1, trp, NULL);
 
-    LSUP_Graph *gr2 = LSUP_graph_copy (gr1);
-    EXPECT_INT_EQ (LSUP_graph_size (gr2), 8);
+    // Copy to graph with same store type.
+    LSUP_Graph *gr2 = LSUP_graph_new (
+            LSUP_iriref_new (NULL, NULL), LSUP_STORE_HTABLE, NULL, NULL, 0);
+    EXPECT_PASS (LSUP_graph_copy_contents (gr1, gr2));
+    EXPECT_INT_EQ (LSUP_graph_size (gr1), LSUP_graph_size (gr2));
 
     for (int i = 0; i < sizeof (trp); i++) {
         log_info ("checking triple #%d.", i);
@@ -256,18 +287,17 @@ static int test_graph_copy()
                 "Triple not in copied graph!");
     }
 
-    LSUP_Graph *gr3;
-    EXPECT_PASS (LSUP_graph_store (gr1, &gr3, NULL));
-
-    ASSERT (
-            LSUP_term_equals (LSUP_graph_uri (gr1), LSUP_graph_uri (gr3)),
-            "Stored graph has different URI than source!");
+    // Copy to graph with a different store type.
+    LSUP_Graph *gr3 = LSUP_graph_new (
+            LSUP_iriref_new (NULL, NULL), LSUP_STORE_MDB, NULL, NULL, 0);
+    EXPECT_PASS (LSUP_graph_copy_contents (gr1, gr3));
+    EXPECT_INT_EQ (LSUP_graph_size (gr1), LSUP_graph_size (gr2));
 
     for (int i = 0; i < sizeof (trp); i++) {
         log_info ("checking triple #%d.", i);
         ASSERT (
                 LSUP_graph_contains (gr3, trp + i),
-                "Triple not in stored graph!");
+                "Triple not in copied graph!");
     }
 
     LSUP_graph_free (gr3);

test/test_store.c

@@ -0,0 +1,380 @@
+#include "test.h"
+#include "store.h"
+#include "assets/triples.h"
+
+
+#define STORE_ID_MDB "file:///tmp/testdb";
+#define STORE_ID_HTABLE LSUP_NS "dummy";
+
+static LSUP_Store store_s;
+static LSUP_Store *store = &store_s;
+
+
+/** @brief Test triple store.
+ *
+ * This runs context-aware stores in triple mode. They should behave exactly
+ * in the same way as non-context stores.
+ */
+static int test_triple_store()
+{
+    if (store->sif->setup_fn)
+        EXPECT_PASS (store->sif->setup_fn (store->id, true));
+
+    log_info ("Testing triple store for %s", store->id);
+    store->data = store->sif->new_fn (store->id, 0);
+    ASSERT (store->data != NULL, "Error creating store data back end!");
+
+    LSUP_Triple *trp = create_triples();
+    LSUP_BufferTriple ser_trp[NUM_TRP];
+
+    for (int i = 0; i < NUM_TRP; i++) {
+        LSUP_BufferTriple *tmp = LSUP_triple_serialize (trp + i);
+        ser_trp[i] = *tmp;
+        free (tmp);
+    }
+
+    // Test adding.
+    void *it = store->sif->add_init_fn (store->data, NULL);
+    size_t ins = 0;
+    for (size_t i = 0; i < NUM_TRP; i++) {
+        LSUP_rc rc = store->sif->add_iter_fn (it, ser_trp + i);
+        ASSERT (rc >= 0, "Error inserting triples!");
+        if (rc == LSUP_OK) ins++;
+    }
+    store->sif->add_done_fn (it);
+
+    EXPECT_INT_EQ (ins, 8);
+    EXPECT_INT_EQ (store->sif->size_fn (store->data), ins);
+
+    // Test lookups.
+    LSUP_Buffer *lut[12][3] = {
+        {NULL, NULL, NULL},
+
+        {ser_trp[0].s, NULL, NULL},
+        {ser_trp[2].s, NULL, NULL},
+        {NULL, ser_trp[0].p, NULL},
+        {NULL, ser_trp[0].s, NULL},
+        {NULL, NULL, ser_trp[6].o},
+
+        {ser_trp[4].s, ser_trp[4].p, NULL},
+        {NULL, ser_trp[7].p, ser_trp[7].o},
+        {ser_trp[5].s, NULL, ser_trp[5].o},
+        {ser_trp[5].s, NULL, ser_trp[5].o},
+
+        {ser_trp[4].s, ser_trp[4].p, ser_trp[4].o},
+        {ser_trp[4].s, ser_trp[4].p, ser_trp[6].o},
+    };
+
+    LSUP_Buffer *luc[12] = {
+        NULL,
+
+        NULL,
+        ser_trp[2].s,
+        NULL,
+        NULL,
+        NULL,
+
+        NULL,
+        NULL,
+        NULL,
+        ser_trp[2].s,
+
+        NULL,
+        NULL,
+    };
+
+    size_t results[12] = {
+        8,
+
+        5,
+        // Lookup on nonexisting context is ignored by non-context store.
+        store->sif->features & LSUP_STORE_CTX ? 0 : 1,
+        1, 0, 1,
+
+        2, 1, 2,
+        store->sif->features & LSUP_STORE_CTX ? 0 : 2,
+
+        1, 0,
+    };
+
+    for (int i = 0; i < 12; i++) {
+        size_t ct;
+        log_info ("Testing triple lookup #%d.", i);
+
+        void *it = store->sif->lookup_fn (
+                store->data, lut[i][0], lut[i][1], lut[i][2], luc[i], &ct);
+        ASSERT (it != NULL, "Error creating iterator!");
+        EXPECT_INT_EQ (ct, results[i]);
+
+        store->sif->lu_free_fn (it);
+    }
+
+    for (int i = 0; i < NUM_TRP; i++) {
+        LSUP_buffer_free (ser_trp[i].s);
+        LSUP_buffer_free (ser_trp[i].p);
+        LSUP_buffer_free (ser_trp[i].o);
+    }
+
+    store->sif->free_fn (store->data);
+    free_triples (trp);
+
+    return 0;
+}
+
+
+/** @brief Test quad store.
+ *
+ * Insert the same triple set twice with different contexts.
+ *
+ * This is skipped for non-context stores.
+ */
+static int test_quad_store()
+{
+    if (!(store->sif->features & LSUP_STORE_CTX)) return 0;
+
+    if (store->sif->setup_fn)
+        EXPECT_PASS (store->sif->setup_fn (store->id, true));
+
+    log_info ("Testing quad store for %s", store->id);
+
+    store->data = store->sif->new_fn (store->id, 0);
+    ASSERT (store->data != NULL, "Error creating store data back end!");
+
+    LSUP_Triple *trp = create_triples();
+    LSUP_BufferTriple ser_trp[NUM_TRP];
+
+    for (int i = 0; i < NUM_TRP; i++) {
+        LSUP_BufferTriple *tmp = LSUP_triple_serialize (trp + i);
+        ser_trp[i] = *tmp;
+        free (tmp);
+    }
+
+    void *it;
+    size_t ins;
+
+    // Only triples 0÷5 in default context.
+    it = store->sif->add_init_fn (store->data, NULL);
+    ins = 0;
+    for (size_t i = 0; i < 6; i++) {
+        log_info ("Inserting triple #%d in default context.", i);
+        LSUP_rc rc = store->sif->add_iter_fn (it, ser_trp + i);
+        EXPECT_PASS (rc);
+        if (rc == LSUP_OK) ins++;
+    }
+    store->sif->add_done_fn (it);
+    EXPECT_INT_EQ (ins, 6);
+
+    LSUP_Buffer *sc1 = LSUP_default_ctx_buf;
+
+    LSUP_Term *ctx2 = LSUP_iriref_new("urn:c:2", NULL);
+    LSUP_Buffer *sc2 = LSUP_term_serialize (ctx2);
+
+    // Only triples 4÷9 in context 2 (effectively 4 non-duplicates).
+    it = store->sif->add_init_fn (store->data, sc2);
+    ASSERT (it != NULL, "Error creating iterator!");
+    ins = 0;
+    for (size_t i = 4; i < 10; i++) {
+        log_info ("Inserting triple #%d in context 2.", i);
+        LSUP_rc rc = store->sif->add_iter_fn (it, ser_trp + i);
+        ASSERT (rc == LSUP_OK || rc == LSUP_NOACTION, "Error adding triples!");
+        if (rc == LSUP_OK) ins++;
+    }
+    store->sif->add_done_fn (it);
+    EXPECT_INT_EQ (ins, 4);
+
+    // 6 triples in ctx1 + 6 in ctx2 - 2 duplicates
+    EXPECT_INT_EQ (store->sif->size_fn (store->data), 10);
+
+    // This context has no triples.
+    LSUP_Term *ctx3 = LSUP_iriref_new("urn:c:3", NULL);
+    LSUP_Buffer *sc3 = LSUP_term_serialize (ctx3);
+
+    // Test lookups.
+    LSUP_Buffer *lut[41][3] = {
+        // Any context
+        {NULL, NULL, NULL},                                 // #0
+
+        {ser_trp[0].s, NULL, NULL},                         // #1
+        {NULL, ser_trp[0].p, NULL},                         // #2
+        {NULL, ser_trp[0].s, NULL},                         // #3
+        {NULL, NULL, ser_trp[6].o},                         // #4
+
+        {ser_trp[4].s, ser_trp[4].p, NULL},                 // #5
+        {NULL, ser_trp[7].p, ser_trp[7].o},                 // #6
+        {ser_trp[5].s, NULL, ser_trp[5].o},                 // #7
+
+        {ser_trp[4].s, ser_trp[4].p, ser_trp[4].o},         // #8
+        {ser_trp[2].s, ser_trp[4].p, ser_trp[5].o},         // #9
+
+        // Context 1 (trp[0÷5])
+        {NULL, NULL, NULL},                                 // #10
+
+        {ser_trp[0].s, NULL, NULL},                         // #11
+        {ser_trp[2].s, NULL, NULL},                         // #12
+        {NULL, ser_trp[0].p, NULL},                         // #13
+        {NULL, ser_trp[6].p, NULL},                         // #14
+        {NULL, NULL, ser_trp[6].o},                         // #15
+
+        {ser_trp[4].s, ser_trp[4].p, NULL},                 // #16
+        {NULL, ser_trp[7].p, ser_trp[7].o},                 // #17
+        {ser_trp[5].s, NULL, ser_trp[5].o},                 // #18
+
+        {ser_trp[4].s, ser_trp[4].p, ser_trp[4].o},         // #19
+        {ser_trp[6].s, ser_trp[6].p, ser_trp[6].o},         // #20
+
+
+        // Context 2 (trp[4÷9])
+        {NULL, NULL, NULL},                                 // #21
+
+        {ser_trp[0].s, NULL, NULL},                         // #22
+        {NULL, ser_trp[0].p, NULL},                         // #23
+        {NULL, ser_trp[0].s, NULL},                         // #24
+        {NULL, NULL, ser_trp[6].o},                         // #25
+
+        {ser_trp[4].s, ser_trp[4].p, NULL},                 // #26
+        {NULL, ser_trp[7].p, ser_trp[7].o},                 // #27
+        {ser_trp[5].s, NULL, ser_trp[5].o},                 // #28
+
+        {ser_trp[4].s, ser_trp[4].p, ser_trp[4].o},         // #29
+        {ser_trp[6].s, ser_trp[6].p, ser_trp[6].o},         // #30
+
+
+        // Non-existing context
+        {NULL, NULL, NULL},                                 // #31
+
+        {ser_trp[0].s, NULL, NULL},                         // #32
+        {NULL, ser_trp[0].p, NULL},                         // #33
+        {NULL, ser_trp[0].s, NULL},                         // #34
+        {NULL, NULL, ser_trp[6].o},                         // #35
+
+        {ser_trp[4].s, ser_trp[4].p, NULL},                 // #36
+        {NULL, ser_trp[7].p, ser_trp[7].o},                 // #37
+        {ser_trp[5].s, NULL, ser_trp[5].o},                 // #38
+
+        {ser_trp[4].s, ser_trp[4].p, ser_trp[4].o},         // #39
+        {ser_trp[6].s, ser_trp[6].p, ser_trp[6].o},         // #40
+    };
+
+    LSUP_Buffer *luc[41] = {
+        // Any context
+        NULL,                                               // #0
+        NULL, NULL, NULL, NULL,                             // #1-#4
+        NULL, NULL, NULL,                                   // #5-#7
+        NULL, NULL,                                         // #8-#9
+
+        // Context 1 (trp[0÷5])
+        sc1,                                                // #10
+        sc1, sc1, sc1, sc1, sc1,                            // #11-#15
+        sc1, sc1, sc1,                                      // #16-#18
+        sc1, sc1,                                           // #19-#20
+
+        // Context 2 (trp[4÷9])
+        sc2,                                                // #21
+        sc2, sc2, sc2, sc2,                                 // #22-#25
+        sc2, sc2, sc2,                                      // #26-#28
+        sc2, sc2,                                           // #29-#30
+
+        // Non-existing context
+        sc3,                                                // #31
+        sc3, sc3, sc3, sc3,                                 // #32-#35
+        sc3, sc3, sc3,                                      // #36-#38
+        sc3, sc3,                                           // #39-#40
+    };
+
+    size_t results[41] = {
+        // NULL ctx
+        8,                      // #0
+        5, 1, 0, 1,             // #1-#4
+        2, 1, 2,                // #5-#7
+        1, 0,                   // #8-#9
+
+        // ctx1
+        6,                      // #10
+        4, 1, 1, 0, 0,          // #11-#15
+        1, 0, 1,                // #16-#18
+        1, 0,                   // #19-#20
+
+        // ctx2
+        4,                      // #21
+        3, 0, 0, 1,             // #22-#25
+        2, 1, 2,                // #26-#28
+        1, 1,                   // #29-#30
+
+        // ctx3
+        0,                      // #31-#32
+        0, 0, 0, 0,             // #33-#36
+        0, 0, 0,                // #37-#39
+        0, 0,                   // #40
+    };
+
+    int ctx_ct[10] = {
+        // BEGIN ctx1 (triples 0÷5)
+        1, 1, 1, 1,
+        // BEGIN ctx2 (triples 4÷9)
+        2, 2,
+        // END ctx 1
+        1, 1, 1, 1,
+        // END ctx 2
+    };
+
+    for (int i = 0; i < 41; i++) {
+        size_t ct;
+
+        log_info ("Checking triple #%d.", i);
+        void *it = store->sif->lookup_fn (
+                store->data, lut[i][0], lut[i][1], lut[i][2], luc[i], &ct);
+        ASSERT (it != NULL, "Lookup error!");
+        EXPECT_INT_EQ (ct, results[i]);
+
+        store->sif->lu_free_fn (it);
+    }
+
+    // Check triple contexts.
+    for (int i = 0; i < 10; i++) {
+        void *it = store->sif->lookup_fn (
+                store->data, ser_trp[i].s, ser_trp[i].p, ser_trp[i].o,
+                NULL, NULL);
+        log_info ("Checking contexts for triple %d.", i);
+        LSUP_Buffer *ctx_a;
+        EXPECT_PASS (store->sif->lu_next_fn (it, NULL, &ctx_a));
+        store->sif->lu_free_fn (it);
+
+        ASSERT (ctx_a != NULL, "No contexts found!");
+
+        size_t j = 0;
+        while (ctx_a[j].addr) j++;
+        free (ctx_a);
+
+        EXPECT_INT_EQ (j, ctx_ct[i]);
+    }
+
+    for (int i = 0; i < NUM_TRP; i++) {
+        LSUP_buffer_free (ser_trp[i].s);
+        LSUP_buffer_free (ser_trp[i].p);
+        LSUP_buffer_free (ser_trp[i].o);
+    }
+
+    LSUP_term_free (ctx2);
+    LSUP_term_free (ctx3);
+    LSUP_buffer_free (sc2);
+    LSUP_buffer_free (sc3);
+    free_triples (trp);
+
+    store->sif->free_fn (store->data);
+
+    return 0;
+}
+
+
+int store_tests()
+{
+#define ENTRY(a, b) \
+    store->type = LSUP_STORE_##a; \
+    store->id = STORE_ID_##a; \
+    store->sif = &b; \
+    RUN (test_triple_store); \
+    RUN (test_quad_store);
+BACKEND_TBL
+#undef ENTRY
+    return 0;
+}

test/test_store_ht.c

@@ -55,7 +55,7 @@ static int test_htstore()
         1, 0,
     };
 
-    LSUP_BufferTriple *sspo = STRP_DUMMY;
+    LSUP_BufferTriple *sspo = BTRP_DUMMY;
     for (int i = 0; i < NUM_TRP; i++) {
         size_t ct, ct2 = 0;
         log_info ("Testing triple lookup #%d.", i);

test/test_store_mdb.c

@@ -1,9 +1,13 @@
 #include "test.h"
-#include "store_mdb.h"
+#include "store.h"
 #include "assets/triples.h"
 
 
-static char *path = "/tmp/testdb";
+#define STORE_ID_MDB "file:///tmp/testdb";
+#define STORE_ID_HTABLE LSUP_NS "dummy";
+
+static LSUP_Store store_s;
+static LSUP_Store *store = &store_s;
 
 
 /** @brief Test triple store.
@@ -321,7 +325,13 @@ static int test_quad_store()
 
 int store_mdb_tests()
 {
-    RUN (test_triple_store);
+#define ENTRY(a, b) \
+    store->type = LSUP_STORE_##a; \
+    store->id = STORE_ID_##a; \
+    store->sif = &b; \
+    RUN (test_triple_store); \
     RUN (test_quad_store);
+BACKEND_TBL
+#undef ENTRY
     return 0;
 }