triplestore#

A simple triplestore for strings.

This library defines triplets as subject-predicate-object tuplets with an id. This allow a allows the subject or object to refer to another triplet via its id, as one would expect for RDF triplets (see https://en.wikipedia.org/wiki/Semantic_triple).

Defines

XML#: Namespaces

XSD#

RDF#

RDFS#

OWL#

SKOS#

DCTERMS#

EMMO#

SOFT#

Typedefs

typedef struct _TripleStore TripleStore#: Triplet store.

typedef struct _TripleState TripleState#: State used by triplestore_find. Don’t rely on current definition, it may be optimised later.

Functions

int triplestore_remove_by_id(TripleStore *ts, const char *id)#: Removes a triple identified by it’s id. Returns non-zero if no such triple can be found.

TripleStore *triplestore_create()#: Returns a new empty triplestore or NULL on error.

TripleStore *triplestore_create_with_storage(const char *storage_name, const char *name, const char *options)#

Returns a new empty triplestore.

Without librdf, this behaves like triplestore_create().

Arguments: storage_name: Name of storage module. If NULL, the default storage will be used. name: An identifier for the storage. options: Options for storage_name. May be NULL if the storage allows it. See http://librdf.org/docs/api/redland-storage-modules.html for more info.

Returns NULL on error.

void triplestore_free(TripleStore *ts)#: Frees triplestore.

void triplestore_set_namespace(TripleStore *ts, const char *ns)#: Set default namespace.

const char *triplestore_get_namespace(TripleStore *ts)#: Returns a pointer to default namespace. It may be NULL if it hasn’t been set.

size_t triplestore_length(TripleStore *ts)#: Returns the number of triples in the store.

int triplestore_add(TripleStore *ts, const char *s, const char *p, const char *o, const char *d)#

Adds triple to store.

If d is NULL, the object is considered to be an IRI.

If d starts with ‘@’, the object is considered to be a language-tagged plain text literal. The language code should follow directly after the ‘@’ sign. Ex: “@en”.

Otherwise, the object is considered to be a literal with datatype specified by d. Ex: “xsd:integer”.

int triplestore_add_en(TripleStore *ts, const char *s, const char *p, const char *o)#: Adds a single triple to store. The object is considered to be an english literal. Returns non-zero on error.

int triplestore_add_uri(TripleStore *ts, const char *s, const char *p, const char *o)#: Adds a single triple to store. The object is considered to be an URI. Returns non-zero on error.

int triplestore_add_triples(TripleStore *ts, const Triple *triples, size_t n)#: Adds n triples to store. Returns non-zero on error.

int triplestore_remove(TripleStore *ts, const char *s, const char *p, const char *o, const char *d)#: Removes a triple identified by s, p and o. Any of these may be NULL, allowing for multiple matches. Returns the number of triples removed.

void triplestore_clear(TripleStore *ts)#: Removes all relations in triplestore and releases all references to external memory. Only references to running iterators is kept.

const Triple *triplestore_get(const TripleStore *ts, const char *id)#: Returns a pointer to triple with given id or NULL if no match can be found.

const Triple *triplestore_find_first(const TripleStore *ts, const char *s, const char *p, const char *o, const char *d)#: Returns a pointer to first triple matching s, p and o or NULL if no match can be found. Any of s, p or o may be NULL.

void triplestore_init_state(TripleStore *ts, TripleState *state)#: Initiates a TripleState for triplestore_find().

void triplestore_deinit_state(TripleState *state)#: Deinitiates a TripleState initialised with triplestore_init_state().

void triplestore_reset_state(TripleState *state)#: Resets iterator.

const Triple *triplestore_next(TripleState *state)#: Increments state and returns a pointer to the current triple in the store or NULL if all triples have been visited.

const Triple *triplestore_poll(TripleState *state)#: Returns a pointer to the current triple in the store or NULL if all triples have been visited.

const Triple *triplestore_find(TripleState *state, const char *s, const char *p, const char *o, const char *d)#

Return next triple matching s-p-o triple, where d is the datatype of the object. Any of s, p, o or d may be NULL, in which case they will match anything.

If d starts with ‘@’, it will match language-tagged plain text literal objects whos XML language abbreviation matches the string following the ‘@’-sign.

if d is NUL (empty string), it will match non-literal objects.

Any other non-NULL d will match literal objects whos datatype are d.

When no more matches can be found, NULL is returned. NULL is also returned on error.

This function should be called iteratively. Before the first call it should be provided a state initialised with triplestore_init_state() and deinitialised with triplestore_deinit_state().

const char *triplestore_value(TripleStore *ts, const char *s, const char *p, const char *o, const char *d, const char *fallback, int any)#

Return pointer to the value for a pair of two criteria.

Useful if one knows that there may only be one value. The returned value is held by the triplestore and should be copied by the user since it may be overwritten by later calls to the triplestore.

Parameters: s, p, o: Criteria to match. Two of these must be non-NULL. d: If not NULL, the required datatype of literal objects. fallback: Value to return if no matches are found. any: If non-zero, return first matching value.

Returns a pointer to the value of the s, p or o that is NULL. On error NULL is returned.

struct _TripleState#

#include <triplestore.h>

State used by triplestore_find. Don’t rely on current definition, it may be optimised later.

Public Members

TripleStore *ts#: reference to corresponding TripleStore

size_t pos#: current position

void *data#: internal data depending on the implementation