Graph patterns

Graph patterns — Collections of triple patterns, sub-graph patterns with operators.

Synopsis

typedef             rasqal_graph_pattern;
int                 rasqal_graph_pattern_add_sub_graph_pattern
                                                        (rasqal_graph_pattern *graph_pattern,
                                                         rasqal_graph_pattern *sub_graph_pattern);
rasqal_expression * rasqal_graph_pattern_get_filter_expression
                                                        (rasqal_graph_pattern *gp);
int                 rasqal_graph_pattern_set_filter_expression
                                                        (rasqal_graph_pattern *gp,
                                                         rasqal_expression *expr);
raptor_sequence *   rasqal_graph_pattern_get_flattened_triples
                                                        (rasqal_query *query,
                                                         rasqal_graph_pattern *graph_pattern);
int                 rasqal_graph_pattern_get_index      (rasqal_graph_pattern *gp);
rasqal_graph_pattern_operator rasqal_graph_pattern_get_operator
                                                        (rasqal_graph_pattern *graph_pattern);
rasqal_literal *    rasqal_graph_pattern_get_origin     (rasqal_graph_pattern *graph_pattern);
rasqal_graph_pattern * rasqal_graph_pattern_get_sub_graph_pattern
                                                        (rasqal_graph_pattern *graph_pattern,
                                                         int idx);
raptor_sequence *   rasqal_graph_pattern_get_sub_graph_pattern_sequence
                                                        (rasqal_graph_pattern *graph_pattern);
rasqal_triple *     rasqal_graph_pattern_get_triple     (rasqal_graph_pattern *graph_pattern,
                                                         int idx);
raptor_sequence *   rasqal_graph_pattern_get_triples    (rasqal_query *query,
                                                         rasqal_graph_pattern *graph_pattern);
rasqal_literal *    rasqal_graph_pattern_get_service    (rasqal_graph_pattern *graph_pattern);
rasqal_variable *   rasqal_graph_pattern_get_variable   (rasqal_graph_pattern *graph_pattern);
enum                rasqal_graph_pattern_operator;
const char *        rasqal_graph_pattern_operator_as_string
                                                        (rasqal_graph_pattern_operator op);
int                 rasqal_graph_pattern_print          (rasqal_graph_pattern *gp,
                                                         FILE *fh);
int                 rasqal_graph_pattern_variable_bound_in
                                                        (rasqal_graph_pattern *gp,
                                                         rasqal_variable *v);
int                 (*rasqal_graph_pattern_visit_fn)    (rasqal_query *query,
                                                         rasqal_graph_pattern *gp,
                                                         void *user_data);
int                 rasqal_graph_pattern_visit          (rasqal_query *query,
                                                         rasqal_graph_pattern *gp,
                                                         rasqal_graph_pattern_visit_fn fn,
                                                         void *user_data);

Description

Graph patterns form a a tree structure that build a rasqal_query top-level graph pattern (see rasqal_query_get_query_graph_pattern()) which may have sub-graph patterns. Graph patterns at the leaf of the tree operate over triple patterns (rasqal_triple) matching the RDF triples in the data sources for RASQAL_GRAPH_PATTERN_OPERATOR_BASIC or RASQAL_GRAPH_PATTERN_OPERATOR_OPTIONAL. Other graph patterns operators operate over sub graph patterns and group them, union them or apply a GRAPH matching keyword (RASQAL_GRAPH_PATTERN_OPERATOR_GRAPH).

Details

rasqal_graph_pattern

rasqal_graph_pattern* graph_pattern;

Rasqal graph pattern class.

rasqal_graph_pattern_add_sub_graph_pattern ()

int                 rasqal_graph_pattern_add_sub_graph_pattern
                                                        (rasqal_graph_pattern *graph_pattern,
                                                         rasqal_graph_pattern *sub_graph_pattern);

Add a sub graph pattern to a graph pattern.

`graph_pattern` :	graph pattern to add to
`sub_graph_pattern` :	graph pattern to add inside
Returns :	non-0 on failure

rasqal_graph_pattern_get_filter_expression ()

rasqal_expression * rasqal_graph_pattern_get_filter_expression
                                                        (rasqal_graph_pattern *gp);

Get a filter graph pattern's constraint expression

`gp` :	rasqal_graph_pattern query object
Returns :	expression or NULL on failure

rasqal_graph_pattern_set_filter_expression ()

int                 rasqal_graph_pattern_set_filter_expression
                                                        (rasqal_graph_pattern *gp,
                                                         rasqal_expression *expr);

Set a filter graph pattern constraint expression

`gp` :	rasqal_graph_pattern query object
`expr` :	rasqal_expression expr - ownership taken
Returns :	non-0 on failure

rasqal_graph_pattern_get_flattened_triples ()

raptor_sequence *   rasqal_graph_pattern_get_flattened_triples
                                                        (rasqal_query *query,
                                                         rasqal_graph_pattern *graph_pattern);

Get the triples inside a tree of graph patterns (BASIC + GRAPH) as a single sequence with GRAPHs turned into triple origin.

The returned sequence and all the rasqal_triple in it are owned by the caller (hold references).

`query` :	query
`graph_pattern` :	graph pattern
Returns :	new sequence of raptor_triple or NULL on failure

rasqal_graph_pattern_get_index ()

int                 rasqal_graph_pattern_get_index      (rasqal_graph_pattern *gp);

Get the graph pattern absolute index in the array of graph patterns.

The graph pattern index is assigned when rasqal_query_prepare() is run on a query containing a graph pattern.

`gp` :	rasqal_graph_pattern graph pattern
Returns :	index or <0 if no index has been assigned yet

rasqal_graph_pattern_get_operator ()

rasqal_graph_pattern_operator rasqal_graph_pattern_get_operator
                                                        (rasqal_graph_pattern *graph_pattern);

Get the graph pattern operator .

The operator for the given graph pattern. See also rasqal_graph_pattern_operator_as_string().

`graph_pattern` :	rasqal_graph_pattern graph pattern object
Returns :	graph pattern operator

rasqal_graph_pattern_get_origin ()

rasqal_literal *    rasqal_graph_pattern_get_origin     (rasqal_graph_pattern *graph_pattern);

Get the graph pattern literal for RASQAL_GRAPH_PATTERN_OPERATOR_GRAPH graph pattern

`graph_pattern` :	rasqal_graph_pattern graph pattern object
Returns :	graph literal parameter or NULL if wrong graph pattern type or not defined

rasqal_graph_pattern_get_sub_graph_pattern ()

rasqal_graph_pattern * rasqal_graph_pattern_get_sub_graph_pattern
                                                        (rasqal_graph_pattern *graph_pattern,
                                                         int idx);

Get a sub-graph pattern inside a graph pattern.

`graph_pattern` :	rasqal_graph_pattern graph pattern object
`idx` :	index into the sequence of sub graph_patterns in the graph pattern
Returns :	rasqal_graph_pattern or NULL if out of range

rasqal_graph_pattern_get_sub_graph_pattern_sequence ()

raptor_sequence *   rasqal_graph_pattern_get_sub_graph_pattern_sequence
                                                        (rasqal_graph_pattern *graph_pattern);

Get the sequence of graph patterns inside a graph pattern .

`graph_pattern` :	rasqal_graph_pattern graph pattern object
Returns :	a raptor_sequence of rasqal_graph_pattern pointers.

rasqal_graph_pattern_get_triple ()

rasqal_triple *     rasqal_graph_pattern_get_triple     (rasqal_graph_pattern *graph_pattern,
                                                         int idx);

Get a triple inside a graph pattern.

`graph_pattern` :	rasqal_graph_pattern graph pattern object
`idx` :	index into the sequence of triples in the graph pattern
Returns :	rasqal_triple or NULL if out of range

rasqal_graph_pattern_get_triples ()

raptor_sequence *   rasqal_graph_pattern_get_triples    (rasqal_query *query,
                                                         rasqal_graph_pattern *graph_pattern);

Get the triples inside this graph pattern (if any).

The returned sequence and all the rasqal_triple in it are owned by the caller (hold references).

`query` :	query
`graph_pattern` :	graph pattern
Returns :	new sequence of raptor_triple or NULL on failure or no triples

rasqal_graph_pattern_get_service ()

rasqal_literal *    rasqal_graph_pattern_get_service    (rasqal_graph_pattern *graph_pattern);

Get the literal for RASQAL_GRAPH_PATTERN_OPERATOR_SERVICE graph pattern

`graph_pattern` :	rasqal_graph_pattern graph pattern object
Returns :	graph variable or NULL if wrong graph pattern or not defined

rasqal_graph_pattern_get_variable ()

rasqal_variable *   rasqal_graph_pattern_get_variable   (rasqal_graph_pattern *graph_pattern);

Get the variable for RASQAL_GRAPH_PATTERN_OPERATOR_LET graph pattern

`graph_pattern` :	rasqal_graph_pattern graph pattern object
Returns :	graph variable or NULL if wrong graph pattern or not defined

enum rasqal_graph_pattern_operator

typedef enum {
  RASQAL_GRAPH_PATTERN_OPERATOR_UNKNOWN   = 0,
  RASQAL_GRAPH_PATTERN_OPERATOR_BASIC     = 1,
  RASQAL_GRAPH_PATTERN_OPERATOR_OPTIONAL  = 2,
  RASQAL_GRAPH_PATTERN_OPERATOR_UNION     = 3,
  RASQAL_GRAPH_PATTERN_OPERATOR_GROUP     = 4,
  RASQAL_GRAPH_PATTERN_OPERATOR_GRAPH     = 5,
  RASQAL_GRAPH_PATTERN_OPERATOR_FILTER    = 6,
  RASQAL_GRAPH_PATTERN_OPERATOR_LET       = 7,
  RASQAL_GRAPH_PATTERN_OPERATOR_SELECT    = 8,
  RASQAL_GRAPH_PATTERN_OPERATOR_SERVICE   = 9,
  RASQAL_GRAPH_PATTERN_OPERATOR_MINUS     = 10,
  RASQAL_GRAPH_PATTERN_OPERATOR_VALUES    = 11,

  RASQAL_GRAPH_PATTERN_OPERATOR_LAST = RASQAL_GRAPH_PATTERN_OPERATOR_VALUES
} rasqal_graph_pattern_operator;

Graph pattern operators

`RASQAL_GRAPH_PATTERN_OPERATOR_UNKNOWN`	Internal.
`RASQAL_GRAPH_PATTERN_OPERATOR_BASIC`	Just triple patterns and constraints.
`RASQAL_GRAPH_PATTERN_OPERATOR_OPTIONAL`	Set of graph patterns (ANDed) and constraints.
`RASQAL_GRAPH_PATTERN_OPERATOR_UNION`	Set of graph patterns (UNIONed) and constraints.
`RASQAL_GRAPH_PATTERN_OPERATOR_GROUP`	Set of graph patterns (ANDed) and constraints.
`RASQAL_GRAPH_PATTERN_OPERATOR_GRAPH`	A graph term + a graph pattern and constraints.
`RASQAL_GRAPH_PATTERN_OPERATOR_FILTER`	A filter graph pattern with an expression
`RASQAL_GRAPH_PATTERN_OPERATOR_LET`	LET ?var := Expression (LAQRS)
`RASQAL_GRAPH_PATTERN_OPERATOR_SELECT`	SELECT graph pattern
`RASQAL_GRAPH_PATTERN_OPERATOR_SERVICE`	SERVICE graph pattern
`RASQAL_GRAPH_PATTERN_OPERATOR_MINUS`	MINUS graph pattern
`RASQAL_GRAPH_PATTERN_OPERATOR_VALUES`	VALUES graph pattern
`RASQAL_GRAPH_PATTERN_OPERATOR_LAST`	Internal.

rasqal_graph_pattern_operator_as_string ()

const char *        rasqal_graph_pattern_operator_as_string
                                                        (rasqal_graph_pattern_operator op);

Get a string for the query verb.

`op` :	the rasqal_graph_pattern_operator verb of the query
Returns :	pointer to a shared string label for the query verb

rasqal_graph_pattern_print ()

int                 rasqal_graph_pattern_print          (rasqal_graph_pattern *gp,
                                                         FILE *fh);

Print a rasqal_graph_pattern in a debug format.

The print debug format may change in any release.

`gp` :	the rasqal_graph_pattern object
`fh` :	the FILE* handle to print to
Returns :	non-0 on failure

rasqal_graph_pattern_variable_bound_in ()

int                 rasqal_graph_pattern_variable_bound_in
                                                        (rasqal_graph_pattern *gp,
                                                         rasqal_variable *v);

Is the variable bound in this graph pattern (not including children)?

`gp` :	graph pattern
`v` :	variable
Returns :	non-0 if variable is bound in the given graph pattern.

rasqal_graph_pattern_visit_fn ()

int                 (*rasqal_graph_pattern_visit_fn)    (rasqal_query *query,
                                                         rasqal_graph_pattern *gp,
                                                         void *user_data);

User function to visit an graph_pattern and operate on it with rasqal_graph_pattern_visit() or rasqal_query_graph_pattern_visit()

`query` :	rasqal_query containing the graph pattern
`gp` :	current graph_pattern
`user_data` :	user data passed in
Returns :	non-0 to truncate the visit

rasqal_graph_pattern_visit ()

int                 rasqal_graph_pattern_visit          (rasqal_query *query,
                                                         rasqal_graph_pattern *gp,
                                                         rasqal_graph_pattern_visit_fn fn,
                                                         void *user_data);

Visit a user function over a rasqal_graph_pattern

If the user function fn returns 0, the visit is truncated.

`query` :	rasqal_query to operate on
`gp` :	rasqal_graph_pattern graph pattern
`fn` :	pointer to function to apply that takes user data and graph pattern parameters
`user_data` :	user data for applied function
Returns :	0 if the visit was truncated.

			Rasqal RDF Query Library Manual
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