Query Query object API, parsing and execution 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. @RASQAL_QUERY_VERB_UNKNOWN: @RASQAL_QUERY_VERB_SELECT: @RASQAL_QUERY_VERB_CONSTRUCT: @RASQAL_QUERY_VERB_DESCRIBE: @RASQAL_QUERY_VERB_ASK: @RASQAL_QUERY_VERB_LAST: @name: @uri: @Returns: @query: @query: @uri: @name_uri: @flags: @Returns: @query: @prefix: @query: @var: @query: @Returns: @query: @Returns: @query: @Returns: @query: @Returns: @query: @idx: @Returns: @query: @Returns: @query: @idx: @Returns: @query: @Returns: @query: @Returns: @query: @idx: @Returns: @query: @Returns: @query: @Returns: @query: @Returns: @query: @Returns: @query: @Returns: @query: @idx: @Returns: @query: @Returns: @query: @idx: @Returns: @query: @Returns: @query: @Returns: @query: @idx: @Returns: @query: @Returns: @query: @Returns: @query: @idx: @Returns: @query: @Returns: @query: @Returns: @query: @name: @Returns: @query: @query_string: @base_uri: @Returns: @query: @fh: @query: @visit_fn: @data: @rdf_query: @prefix: @base: @query: @is_distinct: @query: @user_data: @handler: @query: @user_data: @handler: @query: @user_data: @handler: @query: @limit: @query: @offset: @query: @user_data: @query: @name: @value: @Returns: @query: @user_data: @handler: @verb: @Returns: @iostr: @query: @format_uri: @base_uri: @Returns: @query: @iostr: @string: @len: @Returns: @query: @string: @len: @output_len_p: @Returns: @query: @feature: @value: @Returns: @query: @feature: @value: @Returns: @query: @feature: @Returns: @query: @feature: @Returns: