Triples Source

Triples Source — Source of matches to a triple pattern.

Description

A factory that provides the raw triple matches for a triple pattern against some RDF graph. The rasqal_triples_source_factory must create use a new rasqal_triples_source that can be used to initialise and build a rasqal_triples_match for some rasqal_triple (subject, predicate, object, origin URI).

Details

rasqal_triple_meta

typedef struct {
  /* triple (subject, predicate, object) and origin */
  rasqal_variable* bindings[4];

  rasqal_triples_match *triples_match;

  void *context;

  rasqal_triple_parts parts;

  int is_exact;

  int executed;
} rasqal_triple_meta;

Metadata for triple pattern matching for one triple pattern.

rasqal_variable *bindings[4];

Variable bindings for this triple+origin to set.

rasqal_triples_match *triples_match;

The matcher that is setting these bindings.

void *context;

Context data used by the matcher.

rasqal_triple_parts parts;

Bitmask of rasqal_triple_parts flags describing the parts of the triple pattern that will bind to variables. There may also be variables mentioned that are bound in other triple patterns even if parts is 0.

int is_exact;

unused

int executed;

unused

rasqal_triples_match

typedef struct {
  void *user_data;

  rasqal_triple_parts (*bind_match)(struct rasqal_triples_match_s* rtm, void *user_data, rasqal_variable *bindings[4], rasqal_triple_parts parts);

  void (*next_match)(struct rasqal_triples_match_s* rtm, void *user_data);

  int (*is_end)(struct rasqal_triples_match_s* rtm, void *user_data);

  void (*finish)(struct rasqal_triples_match_s* rtm, void *user_data);

  rasqal_world *world;
} rasqal_triples_match;

Triples match structure as initialised by rasqal_triples_source method init_triples_match.

void *user_data;

User data pointer for factory methods.

bind_match ()

The [4]array (s,p,o,origin) bindings against the current triple match only touching triple parts given. Returns parts that were bound or 0 on failure.

next_match ()

Move to next match.

is_end ()

Check for end of triple match - return non-0 if is end.

finish ()

Finish triples match and destroy any allocated memory.

rasqal_world *world;

rasqal_world object

rasqal_triples_source

typedef struct {
  rasqal_query* query;

  void *user_data;

  int (*init_triples_match)(rasqal_triples_match* rtm, struct rasqal_triples_source_s* rts, void *user_data, rasqal_triple_meta *m, rasqal_triple *t);

  int (*triple_present)(struct rasqal_triples_source_s* rts, void *user_data, rasqal_triple *t);

  void (*free_triples_source)(void *user_data);
} rasqal_triples_source;

Triples source as initialised by a rasqal_triples_source_factory.

rasqal_query *query;

Source for this query.

void *user_data;

Context user data passed into the factory methods.

init_triples_match ()

Factory method to initalise a new rasqal_triples_match.

triple_present ()

Factory method to return presence or absence of a complete triple.

free_triples_source ()

Factory method to deallocate resources.

rasqal_triples_source_factory

typedef struct {
  int version;
  
  void *user_data;
  size_t user_data_size;

  /* API v1 */
  int (*new_triples_source)(rasqal_query* query, void *factory_user_data, void *user_data, rasqal_triples_source* rts);
  /* API v2 onwards */
  int (*init_triples_source)(rasqal_query* query, void *factory_user_data, void *user_data, rasqal_triples_source* rts, rasqal_triples_error_handler handler);
  /* API v3 onwards */
  int (*init_triples_source2)(rasqal_world* world, raptor_sequence* data_graphs, void *factory_user_data, void *user_data, rasqal_triples_source *rts, rasqal_triples_error_handler2 handler, unsigned int flags);
} rasqal_triples_source_factory;

A factory that initialises rasqal_triples_source structures to returning matches to a triple pattern across the dataset formed from the data graphs recorded in the query object.

int version;

API factory version from 1 to 3

void *user_data;

User data for triples_source_factory.

size_t user_data_size;

Size of user_data for new_triples_source.

new_triples_source ()

Create a new triples source - returns non-zero on failure < 0 is a 'no rdf data error', > 0 is an unspecified error. Error messages are generated by rasqal internally. (V1)

init_triples_source ()

Initialise a new triples source V2 for a particular source URI/base URI and syntax. Returns non-zero on failure with errors reported via the handler callback by the implementation. (V2)

init_triples_source2 ()

Initialise a new triples source V3 for a particular source URI/base URI and syntax and given data graphs. Returns non-zero on failure with errors reported via the handler callback by the implementation. If bit 0 of flags is 1, enforce RAPTOR_FEATURE_NO_NET (V3)

rasqal_triples_source_factory_register_fn ()

int                 (*rasqal_triples_source_factory_register_fn)
                                                        (rasqal_triples_source_factory *factory);

Register a factory for generating triples sources rasqal_triples_source

factory :

factory to register

Returns :

non-0 on failure

enum rasqal_triples_source_feature

typedef enum {
  RASQAL_TRIPLES_SOURCE_FEATURE_NONE,
  RASQAL_TRIPLES_SOURCE_FEATURE_IOSTREAM_DATA_GRAPH
} rasqal_triples_source_feature;

Optional features that may be supported by a triple source factory

RASQAL_TRIPLES_SOURCE_FEATURE_NONE

No feature

RASQAL_TRIPLES_SOURCE_FEATURE_IOSTREAM_DATA_GRAPH

Support raptor_iostream data graphs

rasqal_triples_error_handler ()

void                (*rasqal_triples_error_handler)     (rasqal_query *query,
                                                         raptor_locator *locator,
                                                         const char *message);

Triples source factory error handler callback.

query :

query object

locator :

error locator (or NULL)

message :

error message

rasqal_triples_error_handler2 ()

void                (*rasqal_triples_error_handler2)    (rasqal_world *world,
                                                         raptor_locator *locator,
                                                         const char *message);

Triples source factory error handler callback.

world :

world object

locator :

error locator (or NULL)

message :

error message

rasqal_set_triples_source_factory ()

int                 rasqal_set_triples_source_factory   (rasqal_world *world,
                                                         rasqal_triples_source_factory_register_fn register_fn,
                                                         void *user_data);

Register a factory to generate triple sources.

Registers the factory that returns triples sources. Note that there is only one of these per runtime.

The rasqal_triples_source_factory factory method new_triples_source is called with the user data for some query and rasqal_triples_source.

world :

rasqal_world object

register_fn :

registration function

user_data :

user data for registration

Returns :

non-zero on failure

RASQAL_TRIPLES_SOURCE_FACTORY_MIN_VERSION

#define RASQAL_TRIPLES_SOURCE_FACTORY_MIN_VERSION 1

Lowest accepted rasqal_triples_source_factory API version


RASQAL_TRIPLES_SOURCE_FACTORY_MAX_VERSION

#define RASQAL_TRIPLES_SOURCE_FACTORY_MAX_VERSION 3

Highest accepted rasqal_triples_source_factory API version


RASQAL_TRIPLES_SOURCE_MIN_VERSION

#define RASQAL_TRIPLES_SOURCE_MIN_VERSION 1

Lowest accepted rasqal_triples_source API version


RASQAL_TRIPLES_SOURCE_MAX_VERSION

#define RASQAL_TRIPLES_SOURCE_MAX_VERSION 2

Highest accepted rasqal_triples_source API version



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