Query

Query — Query object API, parsing and execution

Synopsis

enum                rasqal_query_verb;
typedef             rasqal_query;
rasqal_query*       rasqal_new_query                    (rasqal_world *world,
                                                         const char *name,
                                                         unsigned char *uri);
void                rasqal_free_query                   (rasqal_query *query);
int                 rasqal_query_add_data_graph         (rasqal_query *query,
                                                         raptor_uri *uri,
                                                         raptor_uri *name_uri,
                                                         int flags);
int                 rasqal_query_add_prefix             (rasqal_query *query,
                                                         rasqal_prefix *prefix);
int                 rasqal_query_add_variable           (rasqal_query *query,
                                                         rasqal_variable *var);
rasqal_query_results* rasqal_query_execute              (rasqal_query *query);
raptor_sequence*    rasqal_query_get_all_variable_sequence
                                                        (rasqal_query *query);
raptor_sequence*    rasqal_query_get_anonymous_variable_sequence
                                                        (rasqal_query *query);
raptor_sequence*    rasqal_query_get_bound_variable_sequence
                                                        (rasqal_query *query);
rasqal_triple*      rasqal_query_get_construct_triple   (rasqal_query *query,
                                                         int idx);
raptor_sequence*    rasqal_query_get_construct_triples_sequence
                                                        (rasqal_query *query);
rasqal_data_graph*  rasqal_query_get_data_graph         (rasqal_query *query,
                                                         int idx);
raptor_sequence*    rasqal_query_get_data_graph_sequence
                                                        (rasqal_query *query);
int                 rasqal_query_get_distinct           (rasqal_query *query);
int                 rasqal_query_get_explain            (rasqal_query *query);
rasqal_expression*  rasqal_query_get_group_condition    (rasqal_query *query,
                                                         int idx);
raptor_sequence*    rasqal_query_get_group_conditions_sequence
                                                        (rasqal_query *query);
rasqal_graph_pattern* rasqal_query_get_graph_pattern    (rasqal_query *query,
                                                         int idx);
raptor_sequence*    rasqal_query_get_graph_pattern_sequence
                                                        (rasqal_query *query);
const char*         rasqal_query_get_label              (rasqal_query *query);
int                 rasqal_query_get_limit              (rasqal_query *query);
const char*         rasqal_query_get_name               (rasqal_query *query);
int                 rasqal_query_get_offset             (rasqal_query *query);
rasqal_expression*  rasqal_query_get_order_condition    (rasqal_query *query,
                                                         int idx);
raptor_sequence*    rasqal_query_get_order_conditions_sequence
                                                        (rasqal_query *query);
rasqal_prefix*      rasqal_query_get_prefix             (rasqal_query *query,
                                                         int idx);
raptor_sequence*    rasqal_query_get_prefix_sequence    (rasqal_query *query);
rasqal_graph_pattern* rasqal_query_get_query_graph_pattern
                                                        (rasqal_query *query);
rasqal_triple*      rasqal_query_get_triple             (rasqal_query *query,
                                                         int idx);
raptor_sequence*    rasqal_query_get_triple_sequence    (rasqal_query *query);
void*               rasqal_query_get_user_data          (rasqal_query *query);
rasqal_variable*    rasqal_query_get_variable           (rasqal_query *query,
                                                         int idx);
rasqal_query_verb   rasqal_query_get_verb               (rasqal_query *query);
int                 rasqal_query_get_wildcard           (rasqal_query *query);
int                 rasqal_query_has_variable           (rasqal_query *query,
                                                         unsigned char *name);
int                 rasqal_query_prepare                (rasqal_query *query,
                                                         unsigned char *query_string,
                                                         raptor_uri *base_uri);
void                rasqal_query_print                  (rasqal_query *query,
                                                         FILE *fh);
void                rasqal_query_graph_pattern_visit    (rasqal_query *query,
                                                         rasqal_graph_pattern_visit_fn visit_fn,
                                                         void *data);
void                rasqal_query_set_default_generate_bnodeid_parameters
                                                        (rasqal_query *rdf_query,
                                                         char *prefix,
                                                         int base);
void                rasqal_query_set_distinct           (rasqal_query *query,
                                                         int distinct_mode);
void                rasqal_query_set_explain            (rasqal_query *query,
                                                         int is_explain);
void                rasqal_query_set_error_handler      (rasqal_query *query,
                                                         void *user_data,
                                                         raptor_message_handler handler);
void                rasqal_query_set_fatal_error_handler
                                                        (rasqal_query *query,
                                                         void *user_data,
                                                         raptor_message_handler handler);
void                rasqal_query_set_generate_bnodeid_handler
                                                        (rasqal_query *query,
                                                         void *user_data,
                                                         rasqal_generate_bnodeid_handler handler);
void                rasqal_query_set_limit              (rasqal_query *query,
                                                         int limit);
void                rasqal_query_set_offset             (rasqal_query *query,
                                                         int offset);
void                rasqal_query_set_user_data          (rasqal_query *query,
                                                         void *user_data);
int                 rasqal_query_set_variable           (rasqal_query *query,
                                                         unsigned char *name,
                                                         rasqal_literal *value);
void                rasqal_query_set_warning_handler    (rasqal_query *query,
                                                         void *user_data,
                                                         raptor_message_handler handler);
const char*         rasqal_query_verb_as_string         (rasqal_query_verb verb);
int                 rasqal_query_write                  (raptor_iostream *iostr,
                                                         rasqal_query *query,
                                                         raptor_uri *format_uri,
                                                         raptor_uri *base_uri);
int                 rasqal_query_iostream_write_escaped_counted_string
                                                        (rasqal_query *query,
                                                         raptor_iostream *iostr,
                                                         unsigned char *string,
                                                         size_t len);
unsigned char*      rasqal_query_escape_counted_string  (rasqal_query *query,
                                                         unsigned char *string,
                                                         size_t len,
                                                         size_t *output_len_p);
int                 rasqal_query_set_feature            (rasqal_query *query,
                                                         rasqal_feature feature,
                                                         int value);
int                 rasqal_query_set_feature_string     (rasqal_query *query,
                                                         rasqal_feature feature,
                                                         unsigned char *value);
int                 rasqal_query_get_feature            (rasqal_query *query,
                                                         rasqal_feature feature);
const unsigned char* rasqal_query_get_feature_string    (rasqal_query *query,
                                                         rasqal_feature feature);

Description

This class provides the main interface to the library. A query can be constructed by parsing a string, retrieving it from a URI and/or constructing it via API methods to build the query expression.

The query structures can be read via methods to return the query verb rasqal_query_get_verb(), the rasqal_data_graph RDF data sources with rasqal_query_get_data_graph() etc., the rasqal_graph_pattern tree with rasqal_query_get_query_graph_pattern(), the sequence of order conditions with rasqal_query_get_order_condition() etc., the rasqal_variable selected to return with rasqal_query_get_bound_variable_sequence() or rasqal_query_get_all_variable_sequence(), and so on.

To process a query string, the rasqal_query_prepare() method parses the query string in some query language and initialises the rasqal_query structures.

The query can be evaluated with the internal query engine against some source of matches using rasqal_query_execute() to give an rasqal_query_results. There are multiple forms of results that can include variable bindings, a boolean or an RDF graph that can be tested for with methods on rasqal_query_results and then retrieved.

Details

enum rasqal_query_verb

typedef enum {
  /* internal */
  RASQAL_QUERY_VERB_UNKNOWN   = 0,
  RASQAL_QUERY_VERB_SELECT    = 1,
  RASQAL_QUERY_VERB_CONSTRUCT = 2,
  RASQAL_QUERY_VERB_DESCRIBE  = 3,
  RASQAL_QUERY_VERB_ASK       = 4,
  RASQAL_QUERY_VERB_DELETE    = 5,
  RASQAL_QUERY_VERB_INSERT    = 6,

  /* internal */
  RASQAL_QUERY_VERB_LAST=RASQAL_QUERY_VERB_INSERT
} rasqal_query_verb;

Query main operation verbs describing the major type of query being performed.

RASQAL_QUERY_VERB_UNKNOWN

 Internal

RASQAL_QUERY_VERB_SELECT

 RDQL/SPARQL query select verb.

RASQAL_QUERY_VERB_CONSTRUCT

 SPARQL query construct verb.

RASQAL_QUERY_VERB_DESCRIBE

 SPARQL query describe verb.

RASQAL_QUERY_VERB_ASK

 SPARQL query ask verb.

RASQAL_QUERY_VERB_DELETE

 LAQRS query delete verb.

RASQAL_QUERY_VERB_INSERT

 LAQRS query insert verb.

RASQAL_QUERY_VERB_LAST

 Internal

rasqal_query

rasqal_graph_query* query;

Rasqal query class.

rasqal_new_query ()

rasqal_query*       rasqal_new_query                    (rasqal_world *world,
                                                         const char *name,
                                                         unsigned char *uri);

Constructor - create a new rasqal_query object.

A query language can be named or identified by a URI, either of which is optional. The default query language will be used if both are NULL. rasqal_languages_enumerate returns information on the known names, labels and URIs.

world :

 rasqal_world object

name :

 the query language name (or NULL)

uri :

 raptor_uri language uri (or NULL)

Returns :

 a new rasqal_query object or NULL on failure

rasqal_free_query ()

void                rasqal_free_query                   (rasqal_query *query);

Destructor - destroy a rasqal_query object.

query :

 rasqal_query object

rasqal_query_add_data_graph ()

int                 rasqal_query_add_data_graph         (rasqal_query *query,
                                                         raptor_uri *uri,
                                                         raptor_uri *name_uri,
                                                         int flags);

Add a data graph to the query.

named_uri must be given if flags RASQAL_DATA_GRAPH_NAMED is set. It is the name of the graph and also used as the base URI when resolving any relative URIs for the graph in uri.

query :

 rasqal_query query object

uri :

 raptor_uri source uri for retrieval

name_uri :

 raptor_uri name uri (or NULL)

flags :

 RASQAL_DATA_GRAPH_NAMED or RASQAL_DATA_GRAPH_BACKGROUND

Returns :

 non-0 on failure

rasqal_query_add_prefix ()

int                 rasqal_query_add_prefix             (rasqal_query *query,
                                                         rasqal_prefix *prefix);

Add a namespace prefix to the query.

If the prefix has already been used, the old URI will be overridden.

query :

 rasqal_query query object

prefix :

 rasqal_prefix namespace prefix, URI

Returns :

 non-0 on failure

rasqal_query_add_variable ()

int                 rasqal_query_add_variable           (rasqal_query *query,
                                                         rasqal_variable *var);

Add a binding variable to the query.

See also rasqal_query_set_variable which assigns or removes a value to a previously added variable in the query.

query :

 rasqal_query query object

var :

 rasqal_variable variable

Returns :

 non-0 on failure

rasqal_query_execute ()

rasqal_query_results* rasqal_query_execute              (rasqal_query *query);

Excute a query - run and return results.

query :

 the rasqal_query object

Returns :

 a rasqal_query_results structure or NULL on failure.

rasqal_query_get_all_variable_sequence ()

raptor_sequence*    rasqal_query_get_all_variable_sequence
                                                        (rasqal_query *query);

Get the sequence of all variables mentioned in the query.

query :

 rasqal_query query object

Returns :

 a raptor_sequence of rasqal_variable pointers.

rasqal_query_get_anonymous_variable_sequence ()

raptor_sequence*    rasqal_query_get_anonymous_variable_sequence
                                                        (rasqal_query *query);

Get the sequence of anonymous variables mentioned in the query.

query :

 rasqal_query query object

Returns :

 a raptor_sequence of rasqal_variable pointers.

rasqal_query_get_bound_variable_sequence ()

raptor_sequence*    rasqal_query_get_bound_variable_sequence
                                                        (rasqal_query *query);

Get the sequence of variables to bind in the query.

This returns the sequence of variables that are explicitly chosen via SELECT in RDQL, SPARQL. Or all variables mentioned with SELECT *

query :

 rasqal_query query object

Returns :

 a raptor_sequence of rasqal_variable pointers.

rasqal_query_get_construct_triple ()

rasqal_triple*      rasqal_query_get_construct_triple   (rasqal_query *query,
                                                         int idx);

Get a triple in the sequence of construct triples.

query :

 rasqal_query query object

idx :

 index into the sequence (0 or larger)

Returns :

 a rasqal_triple pointer or NULL if out of the sequence range

rasqal_query_get_construct_triples_sequence ()

raptor_sequence*    rasqal_query_get_construct_triples_sequence
                                                        (rasqal_query *query);

Get the sequence of triples for a construct.

query :

 rasqal_query query object

Returns :

 a raptor_sequence of rasqal_triple pointers.

rasqal_query_get_data_graph ()

rasqal_data_graph*  rasqal_query_get_data_graph         (rasqal_query *query,
                                                         int idx);

Get a rasqal_data_graph* in the sequence of data_graphs.

query :

 rasqal_query query object

idx :

 index into the sequence (0 or larger)

Returns :

 a rasqal_data_graph pointer or NULL if out of the sequence range

rasqal_query_get_data_graph_sequence ()

raptor_sequence*    rasqal_query_get_data_graph_sequence
                                                        (rasqal_query *query);

Get the sequence of data_graph URIs.

query :

 rasqal_query query object

Returns :

 a raptor_sequence of raptor_uri pointers.

rasqal_query_get_distinct ()

int                 rasqal_query_get_distinct           (rasqal_query *query);

Get the query distinct mode

See rasqal_query_set_distinct() for the distinct modes.

query :

 rasqal_query query object

Returns :

 non-0 if the results should be distinct

rasqal_query_get_explain ()

int                 rasqal_query_get_explain            (rasqal_query *query);

Get the query explain results flag.

query :

 rasqal_query query object

Returns :

 non-0 if the results should be explain

rasqal_query_get_group_condition ()

rasqal_expression*  rasqal_query_get_group_condition    (rasqal_query *query,
                                                         int idx);

Get a query grouping expression in the sequence of query grouping conditions.

query :

 rasqal_query query object

idx :

 index into the sequence (0 or larger)

Returns :

 a rasqal_expression pointer or NULL if out of the sequence range

rasqal_query_get_group_conditions_sequence ()

raptor_sequence*    rasqal_query_get_group_conditions_sequence
                                                        (rasqal_query *query);

Get the sequence of query grouping conditions.

query :

 rasqal_query query object

Returns :

 a raptor_sequence of rasqal_expression pointers.

rasqal_query_get_graph_pattern ()

rasqal_graph_pattern* rasqal_query_get_graph_pattern    (rasqal_query *query,
                                                         int idx);

Get a graph_pattern in the sequence of graph_pattern expressions in the top query graph pattern.

query :

 rasqal_query query object

idx :

 index into the sequence (0 or larger)

Returns :

 a rasqal_graph_pattern pointer or NULL if out of the sequence range

rasqal_query_get_graph_pattern_sequence ()

raptor_sequence*    rasqal_query_get_graph_pattern_sequence
                                                        (rasqal_query *query);

Get the sequence of graph_patterns expressions inside the top query graph pattern.

query :

 rasqal_query query object

Returns :

 a raptor_sequence of rasqal_graph_pattern pointers.

rasqal_query_get_label ()

const char*         rasqal_query_get_label              (rasqal_query *query);

Get a readable label for the query language.

query :

 rasqal_query query object

Returns :

 shared string label value

rasqal_query_get_limit ()

int                 rasqal_query_get_limit              (rasqal_query *query);

Get the query-specified limit on results.

This is the limit given in the query on the number of results allowed.

query :

 rasqal_query query object

Returns :

 integer >=0 if a limit is given, otherwise <0

rasqal_query_get_name ()

const char*         rasqal_query_get_name               (rasqal_query *query);

Get a short name for the query language.

query :

 rasqal_query query object

Returns :

 shared string label value

rasqal_query_get_offset ()

int                 rasqal_query_get_offset             (rasqal_query *query);

Get the query-specified offset on results.

This is the offset given in the query on the number of results allowed.

query :

 rasqal_query query object

Returns :

 integer >=0 if a offset is given, otherwise <0

rasqal_query_get_order_condition ()

rasqal_expression*  rasqal_query_get_order_condition    (rasqal_query *query,
                                                         int idx);

Get a query ordering expression in the sequence of query ordering conditions.

query :

 rasqal_query query object

idx :

 index into the sequence (0 or larger)

Returns :

 a rasqal_expression pointer or NULL if out of the sequence range

rasqal_query_get_order_conditions_sequence ()

raptor_sequence*    rasqal_query_get_order_conditions_sequence
                                                        (rasqal_query *query);

Get the sequence of query ordering conditions.

query :

 rasqal_query query object

Returns :

 a raptor_sequence of rasqal_expression pointers.

rasqal_query_get_prefix ()

rasqal_prefix*      rasqal_query_get_prefix             (rasqal_query *query,
                                                         int idx);

Get a prefix in the sequence of namespsace prefixes in the query.

query :

 rasqal_query query object

idx :

 index into the sequence (0 or larger)

Returns :

 a rasqal_prefix pointer or NULL if out of the sequence range

rasqal_query_get_prefix_sequence ()

raptor_sequence*    rasqal_query_get_prefix_sequence    (rasqal_query *query);

Get the sequence of namespace prefixes in the query.

query :

 rasqal_query query object

Returns :

 a raptor_sequence of rasqal_prefix pointers.

rasqal_query_get_query_graph_pattern ()

rasqal_graph_pattern* rasqal_query_get_query_graph_pattern
                                                        (rasqal_query *query);

Get the top query graph pattern.

query :

 rasqal_query query object

Returns :

 a rasqal_graph_pattern of the top query graph pattern

rasqal_query_get_triple ()

rasqal_triple*      rasqal_query_get_triple             (rasqal_query *query,
                                                         int idx);

Get a triple in the sequence of matching triples in the query.

query :

 rasqal_query query object

idx :

 index into the sequence (0 or larger)

Returns :

 a rasqal_triple pointer or NULL if out of the sequence range

rasqal_query_get_triple_sequence ()

raptor_sequence*    rasqal_query_get_triple_sequence    (rasqal_query *query);

Get the sequence of matching triples in the query.

query :

 rasqal_query query object

Returns :

 a raptor_sequence of rasqal_triple pointers.

rasqal_query_get_user_data ()

void*               rasqal_query_get_user_data          (rasqal_query *query);

Get query user data.

query :

 rasqal_query

Returns :

 user data as set by rasqal_query_set_user_data

rasqal_query_get_variable ()

rasqal_variable*    rasqal_query_get_variable           (rasqal_query *query,
                                                         int idx);

Get a variable in the sequence of variables to bind.

query :

 rasqal_query query object

idx :

 index into the sequence (0 or larger)

Returns :

 a rasqal_variable pointer or NULL if out of the sequence range

rasqal_query_get_verb ()

rasqal_query_verb   rasqal_query_get_verb               (rasqal_query *query);

Get the query verb.

query :

 rasqal_query

Returns :

 the operating verb of the query of type rasqal_query_verb

rasqal_query_get_wildcard ()

int                 rasqal_query_get_wildcard           (rasqal_query *query);

Get the query verb is wildcard flag.

query :

 rasqal_query

Returns :

 non-0 if the query verb was a wildcard (such as SELECT *)

rasqal_query_has_variable ()

int                 rasqal_query_has_variable           (rasqal_query *query,
                                                         unsigned char *name);

Find if the named variable is in the sequence of variables to bind.

query :

 rasqal_query query object

name :

 variable name

Returns :

 non-0 if the variable name was found.

rasqal_query_prepare ()

int                 rasqal_query_prepare                (rasqal_query *query,
                                                         unsigned char *query_string,
                                                         raptor_uri *base_uri);

Prepare a query - typically parse it.

Some query languages may require a base URI to resolve any relative URIs in the query string. If this is not given, the current directory in the filesystem is used as the base URI.

The query string may be NULL in which case it is not parsed and the query parts may be created by API calls such as rasqal_query_add_source etc.

query :

 the rasqal_query object

query_string :

 the query string (or NULL)

base_uri :

 base URI of query string (optional)

Returns :

 non-0 on failure.

rasqal_query_print ()

void                rasqal_query_print                  (rasqal_query *query,
                                                         FILE *fh);

Print a query in a debug format.

query :

 the rasqal_query object

fh :

 the FILE* handle to print to.

rasqal_query_graph_pattern_visit ()

void                rasqal_query_graph_pattern_visit    (rasqal_query *query,
                                                         rasqal_graph_pattern_visit_fn visit_fn,
                                                         void *data);

Visit all graph patterns in a query with a user function visit_fn.

See also rasqal_graph_pattern_visit().

query :

 query

visit_fn :

 user function to operate on

data :

 user data to pass to function

rasqal_query_set_default_generate_bnodeid_parameters ()

void                rasqal_query_set_default_generate_bnodeid_parameters
                                                        (rasqal_query *rdf_query,
                                                         char *prefix,
                                                         int base);

Sets the parameters for the default algorithm used to generate blank node IDs. The default algorithm uses both prefix and base to generate a new identifier. The exact identifier generated is not guaranteed to be a strict concatenation of prefix and base but will use both parts.

For finer control of the generated identifiers, use rasqal_set_default_generate_bnodeid_handler()

If prefix is NULL, the default prefix is used (currently "bnodeid") If base is less than 1, it is initialised to 1.

rdf_query :

 rasqal_query object

prefix :

 prefix string

base :

 integer base identifier

rasqal_query_set_distinct ()

void                rasqal_query_set_distinct           (rasqal_query *query,
                                                         int distinct_mode);

Set the query distinct results mode.

The allowed distinct_mode values are: 0 if not given 1 if DISTINCT: ensure solutions are unique 2 if SPARQL REDUCED: permit elimination of some non-unique solutions

query :

 rasqal_query query object

distinct_mode :

 distinct mode

rasqal_query_set_explain ()

void                rasqal_query_set_explain            (rasqal_query *query,
                                                         int is_explain);

Set the query explain results flag.

query :

 rasqal_query query object

is_explain :

 non-0 if explain

rasqal_query_set_error_handler ()

void                rasqal_query_set_error_handler      (rasqal_query *query,
                                                         void *user_data,
                                                         raptor_message_handler handler);

Set the query error handling function.

The function will receive callbacks when the query fails.

query :

 the query

user_data :

 user data to pass to function

handler :

 pointer to the function

rasqal_query_set_fatal_error_handler ()

void                rasqal_query_set_fatal_error_handler
                                                        (rasqal_query *query,
                                                         void *user_data,
                                                         raptor_message_handler handler);

Set the query error handling function.

The function will receive callbacks when the query fails.

query :

 the query

user_data :

 user data to pass to function

handler :

 pointer to the function

rasqal_query_set_generate_bnodeid_handler ()

void                rasqal_query_set_generate_bnodeid_handler
                                                        (rasqal_query *query,
                                                         void *user_data,
                                                         rasqal_generate_bnodeid_handler handler);

Set the generate blank node ID handler function for the query.

Sets the function to generate blank node IDs for the query. The handler is called with a pointer to the rasqal_query, the user_data pointer and a user_bnodeid which is the value of a user-provided blank node identifier (may be NULL). It can either be returned directly as the generated value when present or modified. The passed in value must be free()d if it is not used.

If handler is NULL, the default method is used

query :

 rasqal_query query object

user_data :

 user data pointer for callback

handler :

 generate blank ID callback function

rasqal_query_set_limit ()

void                rasqal_query_set_limit              (rasqal_query *query,
                                                         int limit);

Set the query-specified limit on results.

This is the limit given in the query on the number of results allowed.

query :

 rasqal_query query object

limit :

 the limit on results, >=0 to set a limit, <0 to have no limit

rasqal_query_set_offset ()

void                rasqal_query_set_offset             (rasqal_query *query,
                                                         int offset);

Set the query-specified offset on results.

This is the offset given in the query on the number of results allowed.

query :

 rasqal_query query object

offset :

 offset for results, >=0 to set an offset, <0 to have no offset

rasqal_query_set_user_data ()

void                rasqal_query_set_user_data          (rasqal_query *query,
                                                         void *user_data);

Set the query user data.

query :

 rasqal_query

user_data :

 some user data to associate with the query

rasqal_query_set_variable ()

int                 rasqal_query_set_variable           (rasqal_query *query,
                                                         unsigned char *name,
                                                         rasqal_literal *value);

Add a binding variable to the query.

See also rasqal_query_add_variable which adds a new binding variable and must be called before this method is invoked.

query :

 rasqal_query query object

name :

 rasqal_variable variable

value :

 rasqal_literal value to set or NULL

Returns :

 non-0 on failure

rasqal_query_set_warning_handler ()

void                rasqal_query_set_warning_handler    (rasqal_query *query,
                                                         void *user_data,
                                                         raptor_message_handler handler);

Set the query warning handling function.

The function will receive callbacks when the query gives a warning.

query :

 the query

user_data :

 user data to pass to function

handler :

 pointer to the function

rasqal_query_verb_as_string ()

const char*         rasqal_query_verb_as_string         (rasqal_query_verb verb);

Get a string for the query verb.

verb :

 the rasqal_query_verb verb of the query

Returns :

 pointer to a shared string label for the query verb

rasqal_query_write ()

int                 rasqal_query_write                  (raptor_iostream *iostr,
                                                         rasqal_query *query,
                                                         raptor_uri *format_uri,
                                                         raptor_uri *base_uri);

Write a query to an iostream in a specified format.

The supported URIs for the format_uri are:

Default: SPARQL Query Language 2006-04-06 http://www.w3.org/TR/2006/CR-rdf-sparql-query-20060406/

iostr :

 raptor_iostream to write the query to

query :

 rasqal_query pointer.

format_uri :

 raptor_uri describing the format to write (or NULL for default)

base_uri :

 raptor_uri base URI of the output format

Returns :

 non-0 on failure

rasqal_query_iostream_write_escaped_counted_string ()

int                 rasqal_query_iostream_write_escaped_counted_string
                                                        (rasqal_query *query,
                                                         raptor_iostream *iostr,
                                                         unsigned char *string,
                                                         size_t len);

Write a string to an iostream in escaped form suitable for the query string.

query :

 rasqal_query object

iostr :

 raptor_iostream to write the escaped string to

string :

 string to escape

len :

 Length of string to escape

Returns :

 non-0 on failure

rasqal_query_escape_counted_string ()

unsigned char*      rasqal_query_escape_counted_string  (rasqal_query *query,
                                                         unsigned char *string,
                                                         size_t len,
                                                         size_t *output_len_p);

Convert a string into an escaped form suitable for the query string.

The returned string must be freed by the caller with rasqal_free_memory()

query :

 rasqal_query object

string :

 string to escape

len :

 Length of string to escape

output_len_p :

 Pointer to store length of output string (or NULL)

Returns :

 the escaped string or NULL on failure.

rasqal_query_set_feature ()

int                 rasqal_query_set_feature            (rasqal_query *query,
                                                         rasqal_feature feature,
                                                         int value);

Set various query features.

The allowed features are available via rasqal_features_enumerate().

query :

 rasqal_query query object

feature :

 feature to set from enumerated rasqal_feature values

value :

 integer feature value

Returns :

 non 0 on failure or if the feature is unknown

rasqal_query_set_feature_string ()

int                 rasqal_query_set_feature_string     (rasqal_query *query,
                                                         rasqal_feature feature,
                                                         unsigned char *value);

Set query features with string values.

The allowed features are available via rasqal_features_enumerate(). If the feature type is integer, the value is interpreted as an integer.

query :

 rasqal_query query object

feature :

 feature to set from enumerated rasqal_feature values

value :

 feature value

Returns :

 non 0 on failure or if the feature is unknown

rasqal_query_get_feature ()

int                 rasqal_query_get_feature            (rasqal_query *query,
                                                         rasqal_feature feature);

Get various query features.

The allowed features are available via rasqal_features_enumerate().

Note: no feature value is negative

query :

 rasqal_query query object

feature :

 feature to get value

Returns :

 feature value or < 0 for an illegal feature

rasqal_query_get_feature_string ()

const unsigned char* rasqal_query_get_feature_string    (rasqal_query *query,
                                                         rasqal_feature feature);

Get query features with string values.

The allowed features are available via rasqal_features_enumerate(). If a string is returned, it must be freed by the caller.

query :

 rasqal_query query object

feature :

 feature to get value

Returns :

 feature value or NULL for an illegal feature or no value
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