lsup_rdf/include/triple.h

#ifndef _LSUP_TRIPLE_H
#define _LSUP_TRIPLE_H

#include "term.h"

typedef struct LSUP_Triple {
    LSUP_Term *s;
    LSUP_Term *p;
    LSUP_Term *o;
} LSUP_Triple;

typedef struct LSUP_SerTriple {
    LSUP_Buffer *s;
    LSUP_Buffer *p;
    LSUP_Buffer *o;
} LSUP_SerTriple;

typedef enum {
    TRP_POS_S = 0,
    TRP_POS_P = 1,
    TRP_POS_O = 2,
} LSUP_TriplePos;


LSUP_Triple *
LSUP_triple_new(LSUP_Term *s, LSUP_Term *p, LSUP_Term *o);

#define TRP_DUMMY LSUP_triple_new (NULL, NULL, NULL)


LSUP_SerTriple *
LSUP_striple_new(LSUP_Buffer *s, LSUP_Buffer *p, LSUP_Buffer *o);

#define STRP_DUMMY LSUP_striple_new (NULL, NULL, NULL)


LSUP_Triple *
LSUP_triple_new_from_striple (const LSUP_SerTriple *sspo);


LSUP_SerTriple *
LSUP_striple_new_from_triple (const LSUP_Triple *spo);


/** @brief Initialize internal term pointers in a heap-allocated triple.
 *
 * NOTE: the term structures are not copied. If the triple is freed with
 * #LSUP_triple_free(), the originally provided terms are freed too.
 *
 * @param spo[in] Triple pointer to initialize.
 */
LSUP_rc
LSUP_triple_init (LSUP_Triple *spo, LSUP_Term *s, LSUP_Term *p, LSUP_Term *o);


/** @brief Initialize internal term pointers in a heap-allocated buffer triple.
 *
 * The triple must be freed with #LSUP_striple_free().
 *
 * @param sspo[in] Serialized triple pointer to initialize.
 */
LSUP_rc
LSUP_striple_init (
        LSUP_SerTriple *sspo, LSUP_Buffer *s, LSUP_Buffer *p, LSUP_Buffer *o);


/** @brief Serialize a RDF triple into a buffer triple.
 *
 * The internal structure must be freed with #LSUP_striple_done after use.
 *
 * @param spo[in] Triple to be serialized.
 * @param sspo[out] Buffer triple handle. It must point to an already allocated
 *  structure.
 *
 * @return LSUP_OK or an error code resulting from #LSUP_term_serialize.
 */
LSUP_rc
LSUP_triple_serialize (const LSUP_Triple *spo, LSUP_SerTriple *sspo);


/** @brief Deserialize a buffer triple into a RDF triple.
 *
 * The internal structure must be freed with #LSUP_triple_done after use.
 *
 * @param sspo[in] Buffer triple to be serialized.
 * @param spo[out] RDF triple handle. It must point to an already allocated
 *  structure.
 *
 * @return LSUP_OK or an error code resulting from #LSUP_term_deserialize.
 */
LSUP_rc
LSUP_triple_deserialize (const LSUP_SerTriple *sspo, LSUP_Triple *spo);


/** @brief Free the internal pointers of a triple.
 *
 * @param spo[in] Triple to be freed.
 */
void
LSUP_triple_done (LSUP_Triple *spo);


/** @brief Free the internal pointers of a buffer triple.
 *
 * @param sspo[in] Buffer triple to be freed.
 */
void
LSUP_striple_done (LSUP_SerTriple *sspo);


/** @brief Free a triple and all its internal pointers.
 *
 * NOTE: If the term pointers are not to be freed (e.g. they are owned by a
 * back end), use a simple free(spo) instead of this.
 *
 * @param spo[in] Triple to be freed.
 */
void
LSUP_triple_free (LSUP_Triple *spo);


/** @brief Free a buffer triple and all its internal pointers.
 *
 * NOTE: If the buffer pointers are not to be freed (e.g. they are owned by a
 * back end), use a simple free(sspo) instead of this.
 *
 * @param sspo[in] Buffer triple to be freed.
 */
void
LSUP_striple_free (LSUP_SerTriple *sspo);


/** @brief Free a buffer triple and its buffer handles but not the buffer data.
 *
 * This is useful when freeing a "dummy" triple whose buffers are owned by the
 * caller but the data the terms point to are owned by the store.
 *
 */
void
LSUP_striple_free_shallow (LSUP_SerTriple *sspo);


#define _FN_BODY \
    if (n == TRP_POS_S) return trp->s; \
    if (n == TRP_POS_P) return trp->p; \
    if (n == TRP_POS_O) return trp->o; \
    return NULL;


/** @brief Get triple by term position.
 *
 * Useful for looping over all terms.
 *
 * @param trp[in] Triple pointer.
 *
 * @param n[in] A number between 0÷2.
 *
 * @return Corresponding triple term or NULL if n is out of range.
 */
inline LSUP_Term *
LSUP_triple_pos (const LSUP_Triple *trp, LSUP_TriplePos n)
{ _FN_BODY }


/** @brief Get serialized triple by term position.
 *
 * Useful for looping over all terms.
 *
 * @param trp[in] Serialized triple pointer.
 *
 * @param n[in] A number between 0÷2.
 *
 * @return Corresponding serialized term or NULL if n is out of range.
 */
inline LSUP_Buffer *
LSUP_striple_pos (const LSUP_SerTriple *trp, LSUP_TriplePos n)
{ _FN_BODY }
#undef _FN_BODY


/** @brief Hash a buffer triple.
 *
 * TODO This doesn't handle blank nodes correctly.
 */
inline LSUP_Key
LSUP_striple_hash (const LSUP_SerTriple *strp)
{
    return XXH64 (
        strp->s->addr, strp->s->size,
        XXH64 (
            strp->p->addr, strp->p->size,
            XXH64 (strp->o->addr, strp->o->size, HASH_SEED)
        )
    );
}


/** @brief Hash a triple.
 *
 * TODO This doesn't handle blank nodes correctly.
 */
inline LSUP_Key
LSUP_triple_hash (const LSUP_Triple *trp)
{
    LSUP_SerTriple *strp = LSUP_striple_new_from_triple (trp);
    LSUP_Key hash = LSUP_striple_hash (strp);
    LSUP_striple_free (strp);

    return hash;
}

#endif