[tracker/async-queries-cursor-review: 1/6] libtracker-data: Added cursor return in TrackerSparqlQuery

[Philip Van Hoof <pvanhoof src gnome org>]

commit 46c9ec21d25be5a9c71988cb1d6324b79869d2de
Author: Philip Van Hoof <philip codeminded be>
Date:   Mon Apr 19 15:41:31 2010 +0200

    libtracker-data: Added cursor return in TrackerSparqlQuery

 src/libtracker-data/tracker-data-query.c      |   19 +++++++
 src/libtracker-data/tracker-data-query.h      |   11 +++--
 src/libtracker-data/tracker-sparql-query.vala |   68 ++++++++++++++++++++++--
 src/libtracker-db/libtracker-db.vapi          |    5 ++
 4 files changed, 93 insertions(+), 10 deletions(-)
---
diff --git a/src/libtracker-data/tracker-data-query.c b/src/libtracker-data/tracker-data-query.c
index 7fd8434..ebf98c8 100644
--- a/src/libtracker-data/tracker-data-query.c
+++ b/src/libtracker-data/tracker-data-query.c
@@ -126,3 +126,22 @@ tracker_data_query_sparql (const gchar  *query,
 	return result_set;
 }
 
+
+TrackerDBCursor *
+tracker_data_query_sparql_cursor (const gchar  *query,
+                                  GError      **error)
+{
+	TrackerSparqlQuery *sparql_query;
+	TrackerDBCursor *cursor;
+
+	g_return_val_if_fail (query != NULL, NULL);
+
+	sparql_query = tracker_sparql_query_new (query);
+
+	cursor = tracker_sparql_query_execute_cursor (sparql_query, error);
+
+	g_object_unref (sparql_query);
+
+	return cursor;
+}
+
diff --git a/src/libtracker-data/tracker-data-query.h b/src/libtracker-data/tracker-data-query.h
index cb7d346..4a16fda 100644
--- a/src/libtracker-data/tracker-data-query.h
+++ b/src/libtracker-data/tracker-data-query.h
@@ -33,10 +33,13 @@ G_BEGIN_DECLS
 #error "only <libtracker-data/tracker-data.h> must be included directly."
 #endif
 
-gint                 tracker_data_query_resource_id (const gchar  *uri);
-TrackerDBResultSet  *tracker_data_query_sparql      (const gchar  *query,
-                                                     GError      **error);
-GPtrArray*           tracker_data_query_rdf_type    (gint          id);
+gint                 tracker_data_query_resource_id   (const gchar  *uri);
+TrackerDBResultSet  *tracker_data_query_sparql        (const gchar  *query,
+                                                       GError      **error);
+TrackerDBCursor     *tracker_data_query_sparql_cursor (const gchar  *query,
+                                                       GError      **error);
+
+GPtrArray*           tracker_data_query_rdf_type      (gint          id);
 
 G_END_DECLS
 
diff --git a/src/libtracker-data/tracker-sparql-query.vala b/src/libtracker-data/tracker-sparql-query.vala
index ef688aa..0215d95 100644
--- a/src/libtracker-data/tracker-sparql-query.vala
+++ b/src/libtracker-data/tracker-sparql-query.vala
@@ -361,7 +361,7 @@ public class Tracker.Sparql.Query : Object {
 		}
 	}
 
-	public DBResultSet? execute () throws DBInterfaceError, SparqlError, DateError {
+	void prepare_execute () throws DBInterfaceError, SparqlError, DateError {
 		assert (!update_extensions);
 
 		scanner = new SparqlScanner ((char*) query_string, (long) query_string.size ());
@@ -375,6 +375,11 @@ public class Tracker.Sparql.Query : Object {
 		}
 
 		parse_prologue ();
+	}
+
+	public DBResultSet? execute () throws DBInterfaceError, SparqlError, DateError {
+
+		prepare_execute ();
 
 		switch (current ()) {
 		case SparqlTokenType.SELECT:
@@ -394,6 +399,29 @@ public class Tracker.Sparql.Query : Object {
 		}
 	}
 
+
+	public DBCursor? execute_cursor () throws DBInterfaceError, SparqlError, DateError {
+
+		prepare_execute ();
+
+		switch (current ()) {
+		case SparqlTokenType.SELECT:
+			return execute_select_cursor ();
+		case SparqlTokenType.CONSTRUCT:
+			throw get_internal_error ("CONSTRUCT is not supported");
+		case SparqlTokenType.DESCRIBE:
+			throw get_internal_error ("DESCRIBE is not supported");
+		case SparqlTokenType.ASK:
+			return execute_ask_cursor ();
+		case SparqlTokenType.INSERT:
+		case SparqlTokenType.DELETE:
+		case SparqlTokenType.DROP:
+			throw get_error ("INSERT and DELETE are not supported in query mode");
+		default:
+			throw get_error ("expected SELECT or ASK");
+		}
+	}
+
 	public PtrArray? execute_update (bool blank) throws DataError, DBInterfaceError, SparqlError, DateError {
 		assert (update_extensions);
 
@@ -442,7 +470,7 @@ public class Tracker.Sparql.Query : Object {
 		return blank_nodes;
 	}
 
-	DBResultSet? exec_sql (string sql) throws DBInterfaceError, SparqlError, DateError {
+	DBStatement prepare_for_exec (string sql) throws DBInterfaceError, SparqlError, DateError {
 		var iface = DBManager.get_db_interface ();
 		var stmt = iface.create_statement ("%s", sql);
 
@@ -467,10 +495,22 @@ public class Tracker.Sparql.Query : Object {
 			i++;
 		}
 
+		return stmt;
+	}
+
+	DBResultSet? exec_sql (string sql) throws DBInterfaceError, SparqlError, DateError {
+		var stmt = prepare_for_exec (sql);
+
 		return stmt.execute ();
 	}
 
-	DBResultSet? execute_select () throws DBInterfaceError, SparqlError, DateError {
+	DBCursor? exec_sql_cursor (string sql) throws DBInterfaceError, SparqlError, DateError {
+		var stmt = prepare_for_exec (sql);
+
+		return stmt.start_cursor ();
+	}
+
+	string get_select_query () throws DBInterfaceError, SparqlError, DateError {
 		// SELECT query
 
 		context = new Context ();
@@ -483,10 +523,18 @@ public class Tracker.Sparql.Query : Object {
 
 		context = context.parent_context;
 
-		return exec_sql (sql.str);
+		return sql.str;
 	}
 
-	DBResultSet? execute_ask () throws DBInterfaceError, SparqlError, DateError {
+	DBResultSet? execute_select () throws DBInterfaceError, SparqlError, DateError {
+		return exec_sql (get_select_query ());
+	}
+
+	DBCursor? execute_select_cursor () throws DBInterfaceError, SparqlError, DateError {
+		return exec_sql_cursor (get_select_query ());
+	}
+
+	string get_ask_query () throws DBInterfaceError, SparqlError, DateError {
 		// ASK query
 
 		var pattern_sql = new StringBuilder ();
@@ -511,7 +559,15 @@ public class Tracker.Sparql.Query : Object {
 
 		context = context.parent_context;
 
-		return exec_sql (sql.str);
+		return sql.str;
+	}
+
+	DBResultSet? execute_ask () throws DBInterfaceError, SparqlError, DateError {
+		return exec_sql (get_ask_query ());
+	}
+
+	DBCursor? execute_ask_cursor () throws DBInterfaceError, SparqlError, DateError {
+		return exec_sql_cursor (get_ask_query ());
 	}
 
 	private void parse_from_or_into_param () throws SparqlError {
diff --git a/src/libtracker-db/libtracker-db.vapi b/src/libtracker-db/libtracker-db.vapi
index d9a69e7..f320ab6 100644
--- a/src/libtracker-db/libtracker-db.vapi
+++ b/src/libtracker-db/libtracker-db.vapi
@@ -51,11 +51,16 @@ namespace Tracker {
 	}
 
 	[CCode (cheader_filename = "libtracker-db/tracker-db-interface.h")]
+	public class DBCursor : GLib.Object {
+	}
+
+	[CCode (cheader_filename = "libtracker-db/tracker-db-interface.h")]
 	public interface DBStatement : GLib.Object {
 		public abstract void bind_double (int index, double value);
 		public abstract void bind_int (int index, int value);
 		public abstract void bind_text (int index, string value);
 		public abstract DBResultSet execute () throws DBInterfaceError;
+		public abstract DBCursor start_cursor () throws DBInterfaceError;
 	}
 }