DatabaseSelection: add method Match()

src/DatabaseSelection.hxx

@@ -26,6 +26,7 @@
 #include <stddef.h>
 
 struct locate_item_list;
+struct song;
 
 struct DatabaseSelection {
 	/**
@@ -47,6 +48,9 @@ struct DatabaseSelection {
 		:uri(_uri), recursive(_recursive), match(_match) {
 		assert(uri != NULL);
 	}
+
+	gcc_pure
+	bool Match(const song &song) const;
 };
 
 #endif