[tracker/wip/carlosg/sparql1.1: 86/201] libtracker-data: Add support for SERVICE{} syntax

[Carlos Garnacho <carlosg src gnome org>]

commit 9ca8b0dd376a2fbf04542256b65892c4d601cc29
Author: Carlos Garnacho <carlosg gnome org>
Date:   Thu May 30 13:55:58 2019 +0200

    libtracker-data: Add support for SERVICE{} syntax

 src/libtracker-data/tracker-db-interface-sqlite.c |   2 +
 src/libtracker-data/tracker-sparql.c              | 125 +++++++++++++++++++---
 2 files changed, 111 insertions(+), 16 deletions(-)
---
diff --git a/src/libtracker-data/tracker-db-interface-sqlite.c 
b/src/libtracker-data/tracker-db-interface-sqlite.c
index d19eb93d9..6ed748176 100644
--- a/src/libtracker-data/tracker-db-interface-sqlite.c
+++ b/src/libtracker-data/tracker-db-interface-sqlite.c
@@ -56,6 +56,7 @@
 #include "tracker-db-manager.h"
 #include "tracker-data-enum-types.h"
 #include "tracker-uuid.h"
+#include "tracker-vtab-service.h"
 #include "tracker-vtab-triples.h"
 
 typedef struct {
@@ -3171,6 +3172,7 @@ tracker_db_interface_init_vtabs (TrackerDBInterface *db_interface,
                                  TrackerOntologies  *ontologies)
 {
        tracker_vtab_triples_init (db_interface->db, ontologies);
+       tracker_vtab_service_init (db_interface->db, ontologies);
        return TRUE;
 }
 
diff --git a/src/libtracker-data/tracker-sparql.c b/src/libtracker-data/tracker-sparql.c
index d457a7603..9c669f378 100644
--- a/src/libtracker-data/tracker-sparql.c
+++ b/src/libtracker-data/tracker-sparql.c
@@ -2423,26 +2423,33 @@ translate_Create (TrackerSparql  *sparql,
                silent = TRUE;
 
        _call_rule (sparql, NAMED_RULE_GraphRef, error);
+       g_assert (!tracker_token_is_empty (&sparql->current_state.graph));
 
-       if (!tracker_token_is_empty (&sparql->current_state.graph)) {
-               const gchar *graph_name;
+       graph_name = tracker_token_get_idstring (&sparql->current_state.graph);
 
-               graph_name = tracker_token_get_idstring (&sparql->current_state.graph);
-
-               if (!tracker_data_manager_create_graph (sparql->data_manager,
-                                                       graph_name,
-                                                       &inner_error)) {
-                       if (silent) {
-                               g_error_free (inner_error);
-                               return TRUE;
-                       } else {
-                               g_propagate_error (error, inner_error);
-                               return FALSE;
-                       }
-               }
+       if (tracker_data_manager_find_graph (sparql->data_manager, graph_name) != 0) {
+               inner_error = g_error_new (TRACKER_SPARQL_ERROR,
+                                          TRACKER_SPARQL_ERROR_CONSTRAINT,
+                                          "Graph '%s' already exists",
+                                          graph_name);
+               goto error;
        }
 
+       if (!tracker_data_manager_create_graph (sparql->data_manager,
+                                               graph_name,
+                                               &inner_error))
+               goto error;
+
        return TRUE;
+
+error:
+       if (silent) {
+               g_error_free (inner_error);
+               return TRUE;
+       } else {
+               g_propagate_error (error, inner_error);
+               return FALSE;
+       }
 }
 
 static gboolean
@@ -3234,9 +3241,95 @@ static gboolean
 translate_ServiceGraphPattern (TrackerSparql  *sparql,
                                GError        **error)
 {
+       gssize pattern_start, pattern_end;
+       TrackerParserNode *pattern, *node;
+       gchar *pattern_str, *escaped_str, *var_str;
+       TrackerContext *context;
+       GList *variables = NULL;
+       TrackerToken service;
+       GString *service_sparql;
+       gboolean silent = FALSE, do_join;
+       gint i = 0;
+
        /* ServiceGraphPattern ::= 'SERVICE' 'SILENT'? VarOrIri GroupGraphPattern
         */
-       _unimplemented ("SERVICE");
+       do_join = !tracker_string_builder_is_empty (sparql->current_state.sql);
+
+       if (do_join) {
+               _prepend_string (sparql, "SELECT * FROM (");
+               _append_string (sparql, ") NATURAL INNER JOIN (");
+       }
+
+       context = tracker_triple_context_new ();
+       tracker_sparql_push_context (sparql, context);
+
+       _expect (sparql, RULE_TYPE_LITERAL, LITERAL_SERVICE);
+
+       if (_accept (sparql, RULE_TYPE_LITERAL, LITERAL_SILENT))
+               silent = TRUE;
+
+       _call_rule (sparql, NAMED_RULE_VarOrIri, error);
+       _init_token (&service, sparql->current_state.prev_node, sparql);
+
+       pattern = _skip_rule (sparql, NAMED_RULE_GroupGraphPattern);
+       _append_string (sparql, "SELECT ");
+       service_sparql = g_string_new ("SELECT ");
+
+       for (node = tracker_sparql_parser_tree_find_first (pattern, TRUE);
+            node;
+            node = tracker_sparql_parser_tree_find_next (node, TRUE)) {
+               const TrackerGrammarRule *rule;
+               TrackerBinding *binding;
+               TrackerVariable *var;
+
+               if (!g_node_is_ancestor ((GNode *) pattern, (GNode *) node))
+                       break;
+
+               rule = tracker_parser_node_get_rule (node);
+
+               if (!tracker_grammar_rule_is_a (rule, RULE_TYPE_TERMINAL,
+                                               TERMINAL_TYPE_VAR1) &&
+                   !tracker_grammar_rule_is_a (rule, RULE_TYPE_TERMINAL,
+                                               TERMINAL_TYPE_VAR2))
+                       continue;
+
+               if (i > 0)
+                       _append_string (sparql, ", ");
+
+               var_str = _extract_node_string (node, sparql);
+               var = _extract_node_variable (node, sparql);
+               variables = g_list_prepend (variables, var);
+               binding = tracker_variable_binding_new (var, NULL, NULL);
+               _add_binding (sparql, binding);
+
+
+               _append_string_printf (sparql, "col%d AS %s ",
+                                      i, tracker_variable_get_sql_expression (var));
+               g_string_append_printf (service_sparql, "?%s ", var_str);
+               g_free (var_str);
+               i++;
+       }
+
+       tracker_parser_node_get_extents (pattern, &pattern_start, &pattern_end);
+       pattern_str = g_strndup (&sparql->sparql[pattern_start], pattern_end - pattern_start);
+       escaped_str = _escape_sql_string (pattern_str);
+       g_string_append (service_sparql, escaped_str);
+       g_free (pattern_str);
+       g_free (escaped_str);
+
+       _append_string_printf (sparql, "FROM tracker_service WHERE service=\"%s\" AND query=\"%s\" AND 
silent=%d ",
+                              tracker_token_get_idstring (&service),
+                              service_sparql->str,
+                              silent);
+
+       tracker_token_unset (&service);
+       tracker_sparql_pop_context (sparql, TRUE);
+       g_string_free (service_sparql, TRUE);
+
+       if (do_join)
+               _append_string (sparql, ") ");
+
+       return TRUE;
 }
 
 static gboolean