]> Graph patterns 3 RASQAL Library Graph patterns Collections of triple patterns, sub-graph patterns with operators. typedef rasqal_graph_pattern; int rasqal_graph_pattern_add_constraint (rasqal_graph_pattern *gp, rasqal_expression *expr); 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_constraint (rasqal_graph_pattern *gp, int idx); raptor_sequence* rasqal_graph_pattern_get_constraint_sequence (rasqal_graph_pattern *gp); 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_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); enum rasqal_graph_pattern_operator; const char* rasqal_graph_pattern_operator_as_string (rasqal_graph_pattern_operator op); void rasqal_graph_pattern_print (rasqal_graph_pattern *gp, FILE *fh); 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); 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). rasqal_graph_patternrasqal_graph_pattern* graph_pattern; Rasqal graph pattern class. rasqal_graph_pattern_add_constraintint rasqal_graph_pattern_add_constraint (rasqal_graph_pattern *gp, rasqal_expression *expr); Add a constraint expression to the graph_pattern. gp : rasqal_graph_pattern query object expr : rasqal_expression expr - ownership taken Returns : non-0 on failure rasqal_graph_pattern_add_sub_graph_patternint 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_constraintrasqal_expression* rasqal_graph_pattern_get_constraint (rasqal_graph_pattern *gp, int idx); Get a constraint in the sequence of constraint expressions in the query. gp : rasqal_graph_pattern query object idx : index into the sequence (0 or larger) Returns : a rasqal_expression pointer or NULL if out of the sequence range rasqal_graph_pattern_get_constraint_sequenceraptor_sequence* rasqal_graph_pattern_get_constraint_sequence (rasqal_graph_pattern *gp); Get the sequence of constraints expressions in the query. gp : rasqal_graph_pattern object Returns : a raptor_sequence of rasqal_expression pointers. rasqal_graph_pattern_get_indexint 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_operatorrasqal_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_sub_graph_patternrasqal_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_sequenceraptor_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_triplerasqal_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_operatortypedef 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_LAST=RASQAL_GRAPH_PATTERN_OPERATOR_GRAPH } 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_LAST Internal. rasqal_graph_pattern_operator_as_stringconst 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_printvoid 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 rasqal_graph_pattern_visit_fnint (*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 : 0 to truncate the visit rasqal_graph_pattern_visitint 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.