Add lilv_world_ask() for simply checking if a statement exists.

git-svn-id: http://svn.drobilla.net/lad/trunk/lilv@4862 a436a847-0d15-0410-975c-d299462d15a1

4 files changed, 37 insertions, 0 deletions

diff --git a/NEWS b/NEWS
index 90f05a8..3ee9bee 100644
--- a/NEWS
+++ b/NEWS
@@ -1,5 +1,6 @@
 lilv (0.15.0) unstable;
 
+  * Add lilv_world_ask() for simply checking if a statement exists.
   * Add lilv_nodes_merge().
   * Support atom:supports in lilv_port_supports_event().
   * Add va_list variant of lilv_plugin_get_num_ports_of_class().
diff --git a/lilv/lilv.h b/lilv/lilv.h
index 1d05883..52e3576 100644
--- a/lilv/lilv.h
+++ b/lilv/lilv.h
@@ -650,6 +650,23 @@ lilv_world_find_nodes(LilvWorld*      world,
                       const LilvNode* object);
 
 /**
+   Return true iff a statement matching a certain pattern exists.
+
+   This is useful for checking if particular statement exists without having to
+   bother with collections and memory management.
+
+   @param subject Subject of statement, or NULL for anything.
+   @param predicate Predicate (key) of statement, or NULL for anything.
+   @param object Object (value) of statement, or NULL for anything.
+*/
+LILV_API
+bool
+lilv_world_ask(LilvWorld*      world,
+               const LilvNode* subject,
+               const LilvNode* predicate,
+               const LilvNode* object);
+
+/**
    @}
    @name Plugin
    @{
diff --git a/src/world.c b/src/world.c
index 773a864..a3f59ed 100644
--- a/src/world.c
+++ b/src/world.c
@@ -219,6 +219,17 @@ lilv_world_ask_internal(LilvWorld*      world,
 	return sord_ask(world->model, subject, predicate, object, NULL);
 }
 
+LILV_API
+bool
+lilv_world_ask(LilvWorld*      world,
+               const LilvNode* subject,
+               const LilvNode* predicate,
+               const LilvNode* object)
+{
+	return sord_ask(
+		world->model, subject->node, predicate->node, object->node, NULL);
+}
+
 LilvNodes*
 lilv_world_find_nodes_internal(LilvWorld*      world,
                                const SordNode* subject,
diff --git a/test/lilv_test.c b/test/lilv_test.c
index 0fade61..48fafa5 100644
--- a/test/lilv_test.c
+++ b/test/lilv_test.c
@@ -562,6 +562,14 @@ test_plugin(void)
 	TEST_ASSERT(!strcmp(lilv_node_as_string(klass_uri),
 			"http://lv2plug.in/ns/lv2core#CompressorPlugin"));
 
+	LilvNode* rdf_type = lilv_new_uri(
+		world, "http://www.w3.org/1999/02/22-rdf-syntax-ns#type");
+	TEST_ASSERT(lilv_world_ask(world,
+	                           lilv_plugin_get_uri(plug),
+	                           rdf_type,
+	                           klass_uri));
+	lilv_node_free(rdf_type);
+
 	const LilvNode* plug_bundle_uri = lilv_plugin_get_bundle_uri(plug);
 	TEST_ASSERT(!strcmp(lilv_node_as_string(plug_bundle_uri), bundle_dir_uri));