[tracker/subqueries] Fix nested subqueries

[Jürg Billeter <juergbi src gnome org>]

commit 47088edf3d2ef171db388962885d2aa37d2badd6
Author: Jürg Billeter <j bitron ch>
Date:   Fri Dec 4 19:36:09 2009 +0100

    Fix nested subqueries

 src/libtracker-data/tracker-sparql-query.vala |   47 +++++++++++++++----------
 1 files changed, 28 insertions(+), 19 deletions(-)
---
diff --git a/src/libtracker-data/tracker-sparql-query.vala b/src/libtracker-data/tracker-sparql-query.vala
index cb73a55..5422ca8 100644
--- a/src/libtracker-data/tracker-sparql-query.vala
+++ b/src/libtracker-data/tracker-sparql-query.vala
@@ -268,7 +268,7 @@ public class Tracker.SparqlQuery : Object {
 	List<Variable> pattern_variables;
 	HashTable<Variable,VariableBindingList> pattern_var_map;
 
-	HashTable<string,Variable> outer_var_map;
+	List<unowned HashTable<string,Variable>> outer_var_maps;
 
 	// All SPARQL variables within a subgraph pattern (used by UNION)
 	HashTable<Variable,int> subgraph_var_set;
@@ -668,6 +668,11 @@ public class Tracker.SparqlQuery : Object {
 			} else {
 				translate_expression_as_string (sql);
 			}
+			if (accept (SparqlTokenType.AS)) {
+				expect (SparqlTokenType.VAR);
+				string variable_name = get_last_string ().substring (1);
+				sql.append_printf (" AS %s", get_variable (variable_name).sql_expression);
+			}
 		}
 	}
 
@@ -1797,7 +1802,8 @@ public class Tracker.SparqlQuery : Object {
 		if (current () == SparqlTokenType.SELECT) {
 			// FIXME ensure that inner variables are only exported if selected
 
-			outer_var_map = var_map;
+			outer_var_maps.append (var_map);
+			var outer_var_map = var_map;
 			var outer_predicate_variable_map = predicate_variable_map;
 			var outer_used_sql_identifiers = used_sql_identifiers;
 			begin_query ();
@@ -2527,23 +2533,26 @@ public class Tracker.SparqlQuery : Object {
 
 	VariableBindingList? get_variable_binding_list (Variable variable) {
 		var binding_list = pattern_var_map.lookup (variable);
-		if (binding_list == null && outer_var_map != null) {
-			// in scalar subquery: check variables of outer query
-			var outer_var = outer_var_map.lookup (variable.name);
-			if (outer_var != null) {
-				// capture outer variable
-				var binding = new VariableBinding ();
-				binding.data_type = outer_var.binding.data_type;
-				binding.variable = get_variable (variable.name);
-				binding.type = outer_var.binding.type;
-				binding.sql_expression = outer_var.sql_expression;
-				binding_list = new VariableBindingList ();
-				pattern_variables.append (binding.variable);
-				pattern_var_map.insert (binding.variable, binding_list);
+		if (binding_list == null && outer_var_maps != null) {
+			// in scalar subquery: check variables of outer queries
+			foreach (unowned HashTable<string,Variable> outer_var_map in outer_var_maps) {
+				var outer_var = outer_var_map.lookup (variable.name);
+				if (outer_var != null) {
+					// capture outer variable
+					var binding = new VariableBinding ();
+					binding.data_type = outer_var.binding.data_type;
+					binding.variable = get_variable (variable.name);
+					binding.type = outer_var.binding.type;
+					binding.sql_expression = outer_var.sql_expression;
+					binding_list = new VariableBindingList ();
+					pattern_variables.append (binding.variable);
+					pattern_var_map.insert (binding.variable, binding_list);
 
-				subgraph_var_set.insert (binding.variable, VariableState.BOUND);
-				binding_list.list.append (binding);
-				binding.variable.binding = binding;
+					subgraph_var_set.insert (binding.variable, VariableState.BOUND);
+					binding_list.list.append (binding);
+					binding.variable.binding = binding;
+					break;
+				}
 			}
 		}
 		return binding_list;