Add lilv_world_get_symbol()

4 files changed, 107 insertions, 0 deletions

diff --git a/NEWS b/NEWS
index 9fc97f9..b620a48 100644
--- a/NEWS
+++ b/NEWS
@@ -2,6 +2,7 @@ lilv (0.22.1) unstable;
 
   * Add new hand-crafted Pythonic bindings with full test coverage
   * Add lv2apply utility for applying plugins to audio files
+  * Add lilv_world_get_symbol()
   * Add lilv_state_set_metadata() for adding state banks/comments/etc
     (based on patch from Hanspeter Portner)
   * Fix crash when state contains non-POD properties
diff --git a/lilv/lilv.h b/lilv/lilv.h
index 1808194..bb2f127 100644
--- a/lilv/lilv.h
+++ b/lilv/lilv.h
@@ -708,6 +708,16 @@ lilv_world_ask(LilvWorld*      world,
                const LilvNode* object);
 
 /**
+   Get an LV2 symbol for some subject.
+
+   This will return the lv2:symbol property of the subject if it is given
+   explicitly, and otherwise will attempt to derive a symbol from the URI.
+   @return A string node that is a valid LV2 symbol, or NULL on error.
+*/
+LILV_API LilvNode*
+lilv_world_get_symbol(LilvWorld* world, const LilvNode* subject);
+
+/**
    @}
    @name Plugin
    @{
diff --git a/src/world.c b/src/world.c
index 8760604..01f4ebe 100644
--- a/src/world.c
+++ b/src/world.c
@@ -1148,3 +1148,51 @@ lilv_world_get_all_plugins(const LilvWorld* world)
 {
 	return world->plugins;
 }
+
+LILV_API LilvNode*
+lilv_world_get_symbol(LilvWorld* world, const LilvNode* subject)
+{
+	// Check for explicitly given symbol
+	SordNode* snode = sord_get(
+		world->model, subject->node, world->uris.lv2_symbol, NULL, NULL);
+
+	if (snode) {
+		LilvNode* ret = lilv_node_new_from_node(world, snode);
+		sord_node_free(world->world, snode);
+		return ret;
+	}
+
+	if (!lilv_node_is_uri(subject)) {
+		return NULL;
+	}
+
+	// Find rightmost segment of URI
+	SerdURI uri;
+	serd_uri_parse((const uint8_t*)lilv_node_as_uri(subject), &uri);
+	const char* str = "_";
+	if (uri.fragment.buf) {
+		str = (const char*)uri.fragment.buf + 1;
+	} else if (uri.query.buf) {
+		str = (const char*)uri.query.buf;
+	} else if (uri.path.buf) {
+		const char* last_slash = strrchr((const char*)uri.path.buf, '/');
+		str = last_slash ? (last_slash + 1) : (const char*)uri.path.buf;
+	}
+
+	// Replace invalid characters
+	const size_t len = strlen(str);
+	char* const  sym = (char*)calloc(1, len);
+	for (size_t i = 0; i < len; ++i) {
+		const char c = str[i];
+		if (!((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') ||
+		      (c == '_') || (i > 0 && c >= '0' && c <= '9'))) {
+			sym[i] = '_';
+		} else {
+			sym[i] = str[i];
+		}
+	}
+
+	LilvNode* ret = lilv_new_string(world, sym);
+	free(sym);
+	return ret;
+}
diff --git a/test/lilv_test.c b/test/lilv_test.c
index fb2b974..7c7e06d 100644
--- a/test/lilv_test.c
+++ b/test/lilv_test.c
@@ -2163,6 +2163,53 @@ test_replace_version(void)
 
 /*****************************************************************************/
 
+static int
+test_get_symbol(void)
+{
+	if (!start_bundle(
+		    MANIFEST_PREFIXES
+		    ":plug a lv2:Plugin ; lv2:symbol \"plugsym\" ; lv2:binary <foo" SHLIB_EXT "> ; rdfs:seeAlso <plugin.ttl> .\n",
+		    BUNDLE_PREFIXES PREFIX_LV2EV
+		    ":plug a lv2:Plugin ; "
+		    PLUGIN_NAME("Test plugin") " ; "
+		    "lv2:symbol \"plugsym\" .")) {
+		return 0;
+	}
+
+	init_uris();
+
+	LilvNode* plug_sym      = lilv_world_get_symbol(world, plugin_uri_value);
+	LilvNode* path          = lilv_new_uri(world, "http://example.org/foo");
+	LilvNode* path_sym      = lilv_world_get_symbol(world, path);
+	LilvNode* query         = lilv_new_uri(world, "http://example.org/foo?bar=baz");
+	LilvNode* query_sym     = lilv_world_get_symbol(world, query);
+	LilvNode* frag          = lilv_new_uri(world, "http://example.org/foo#bar");
+	LilvNode* frag_sym      = lilv_world_get_symbol(world, frag);
+	LilvNode* queryfrag     = lilv_new_uri(world, "http://example.org/foo?bar=baz#quux");
+	LilvNode* queryfrag_sym = lilv_world_get_symbol(world, queryfrag);
+	LilvNode* nonuri        = lilv_new_int(world, 42);
+
+	TEST_ASSERT(lilv_world_get_symbol(world, nonuri) == NULL);
+	TEST_ASSERT(!strcmp(lilv_node_as_string(plug_sym), "plugsym"));
+	TEST_ASSERT(!strcmp(lilv_node_as_string(path_sym), "foo"));
+	TEST_ASSERT(!strcmp(lilv_node_as_string(query_sym), "bar_baz"));
+	TEST_ASSERT(!strcmp(lilv_node_as_string(frag_sym), "bar"));
+	TEST_ASSERT(!strcmp(lilv_node_as_string(queryfrag_sym), "quux"));
+
+	lilv_node_free(nonuri);
+	lilv_node_free(queryfrag_sym);
+	lilv_node_free(queryfrag);
+	lilv_node_free(frag_sym);
+	lilv_node_free(frag);
+	lilv_node_free(query_sym);
+	lilv_node_free(query);
+	lilv_node_free(plug_sym);
+
+	return 1;
+}
+
+/*****************************************************************************/
+
 /* add tests here */
 static struct TestCase tests[] = {
 	TEST_CASE(util),
@@ -2188,6 +2235,7 @@ static struct TestCase tests[] = {
 	TEST_CASE(state),
 	TEST_CASE(reload_bundle),
 	TEST_CASE(replace_version),
+	TEST_CASE(get_symbol),
 	{ NULL, NULL }
 };