input_registry: add _for_each() macros

src/input_init.c

@@ -93,8 +93,7 @@ input_stream_global_init(GError **error_r)
 
 void input_stream_global_finish(void)
 {
-	for (unsigned i = 0; input_plugins[i] != NULL; ++i)
-		if (input_plugins_enabled[i] &&
-		    input_plugins[i]->finish != NULL)
-			input_plugins[i]->finish();
+	input_plugins_for_each_enabled(plugin)
+		if (plugin->finish != NULL)
+			plugin->finish();
 }

src/input_registry.h

@@ -32,4 +32,14 @@ extern const struct input_plugin *const input_plugins[];
 
 extern bool input_plugins_enabled[];
 
+#define input_plugins_for_each(plugin) \
+	for (const struct input_plugin *plugin, \
+		*const*input_plugin_iterator = &input_plugins[0]; \
+		(plugin = *input_plugin_iterator) != NULL; \
+		++input_plugin_iterator)
+
+#define input_plugins_for_each_enabled(plugin) \
+	input_plugins_for_each(plugin) \
+		if (input_plugins_enabled[input_plugin_iterator - input_plugins])
+
 #endif

src/input_stream.c

@@ -39,13 +39,9 @@ input_stream_open(const char *url, GError **error_r)
 
 	assert(error_r == NULL || *error_r == NULL);
 
-	for (unsigned i = 0; input_plugins[i] != NULL; ++i) {
-		const struct input_plugin *plugin = input_plugins[i];
+	input_plugins_for_each_enabled(plugin) {
 		struct input_stream *is;
 
-		if (!input_plugins_enabled[i])
-			continue;
-
 		is = plugin->open(url, &error);
 		if (is != NULL) {
 			assert(is->plugin != NULL);