Triples

Triples — Triple pattern or RDF triple.

Synopsis

                    rasqal_triple;
rasqal_triple *     rasqal_new_triple                   (rasqal_literal *subject,
                                                         rasqal_literal *predicate,
                                                         rasqal_literal *object);
rasqal_triple *     rasqal_new_triple_from_triple       (rasqal_triple *t);
void                rasqal_free_triple                  (rasqal_triple *t);
rasqal_literal *    rasqal_triple_get_origin            (rasqal_triple *t);
enum                rasqal_triple_parts;
int                 rasqal_triple_print                 (rasqal_triple *t,
                                                         FILE *fh);
void                rasqal_triple_set_origin            (rasqal_triple *t,
                                                         rasqal_literal *l);

Description

An object for a triple pattern or an RDF triple in a query. It contains the three parts of an RDF triple - subject, predicate, object as well as origin for matching triples in some graph (such as with the SPARQL GRAPH).

Details

rasqal_triple

typedef struct {
  rasqal_literal* subject;
  rasqal_literal* predicate;
  rasqal_literal* object;
  rasqal_literal* origin;
  unsigned int flags;
} rasqal_triple;

A triple pattern or RDF triple.

This is used as a triple pattern in queries and an RDF triple when generating RDF triples such as with SPARQL CONSTRUCT.

rasqal_literal *subject;

 Triple subject.

rasqal_literal *predicate;

 Triple predicate.

rasqal_literal *object;

 Triple object.

rasqal_literal *origin;

 Triple origin.

unsigned int flags;

 Or of enum rasqal_triple_flags bits.

rasqal_new_triple ()

rasqal_triple *     rasqal_new_triple                   (rasqal_literal *subject,
                                                         rasqal_literal *predicate,
                                                         rasqal_literal *object);

Constructor - create a new rasqal_triple triple or triple pattern. Takes ownership of the literals passed in.

The triple origin can be set with rasqal_triple_set_origin().

subject :

 Triple subject.

predicate :

 Triple predicate.

object :

 Triple object.

Returns :

 a new rasqal_triple or NULL on failure.

rasqal_new_triple_from_triple ()

rasqal_triple *     rasqal_new_triple_from_triple       (rasqal_triple *t);

Copy constructor - create a new rasqal_triple from an existing one.

t :

 Triple to copy.

Returns :

 a new rasqal_triple or NULL on failure.

rasqal_free_triple ()

void                rasqal_free_triple                  (rasqal_triple *t);

Destructor - destroy a rasqal_triple object.

t :

 rasqal_triple object.

rasqal_triple_get_origin ()

rasqal_literal *    rasqal_triple_get_origin            (rasqal_triple *t);

Get the origin field of a rasqal_triple.

t :

 The triple object.

Returns :

 The triple origin or NULL.

enum rasqal_triple_parts

typedef enum {
  RASQAL_TRIPLE_NONE     = 0,
  RASQAL_TRIPLE_SUBJECT  = 1,
  RASQAL_TRIPLE_PREDICATE= 2,
  RASQAL_TRIPLE_OBJECT   = 4,
  RASQAL_TRIPLE_ORIGIN   = 8,
  RASQAL_TRIPLE_GRAPH    = RASQAL_TRIPLE_ORIGIN,
  RASQAL_TRIPLE_SPO      = RASQAL_TRIPLE_SUBJECT | RASQAL_TRIPLE_PREDICATE | RASQAL_TRIPLE_OBJECT,
  RASQAL_TRIPLE_SPOG     = RASQAL_TRIPLE_SPO | RASQAL_TRIPLE_GRAPH
} rasqal_triple_parts;

Flags for parts of a triple.

RASQAL_TRIPLE_NONE

 no parts

RASQAL_TRIPLE_SUBJECT

 Subject present in a triple.

RASQAL_TRIPLE_PREDICATE

 Predicate present in a triple.

RASQAL_TRIPLE_OBJECT

 Object present in a triple.

RASQAL_TRIPLE_ORIGIN

 Origin/graph present in a triple.

RASQAL_TRIPLE_GRAPH

 Alias for RASQAL_TRIPLE_ORIGIN

RASQAL_TRIPLE_SPO

 Subject, Predicate and Object present in a triple.

RASQAL_TRIPLE_SPOG

 Subject, Predicate, Object, Graph present in a triple.

rasqal_triple_print ()

int                 rasqal_triple_print                 (rasqal_triple *t,
                                                         FILE *fh);

Print a Rasqal triple in a debug format.

The print debug format may change in any release.

t :

 rasqal_triple object.

fh :

 The FILE* handle to print to.

Returns :

 non-0 on failure

rasqal_triple_set_origin ()

void                rasqal_triple_set_origin            (rasqal_triple *t,
                                                         rasqal_literal *l);

Set the origin field of a rasqal_triple.

t :

 The triple object.

l :

 The rasqal_literal object to set as origin.
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