New command searchplaylist

src/playlist/Print.cxx

@@ -8,7 +8,9 @@
 #include "PlaylistSong.hxx"
 #include "SongEnumerator.hxx"
 #include "SongPrint.hxx"
+#include "song/Filter.hxx"
 #include "song/DetachedSong.hxx"
+#include "song/LightSong.hxx"
 #include "input/Error.hxx"
 #include "fs/Traits.hxx"
 #include "thread/Mutex.hxx"
@@ -50,13 +52,55 @@ playlist_provider_print(Response &r,
 	}
 }
 
+static void
+playlist_provider_search_print(Response &r,
+			       const SongLoader &loader,
+			       const char *uri,
+			       SongEnumerator &e,
+			       unsigned start_index,
+			       unsigned end_index,
+			       SongFilter *filter) noexcept
+{
+	const auto base_uri = uri != nullptr
+		? PathTraitsUTF8::GetParent(uri)
+		: ".";
+
+	std::unique_ptr<DetachedSong> song;
+
+	unsigned skip = start_index;
+	unsigned n = end_index - start_index;
+
+	while ((song = e.NextSong()) != nullptr) {
+		const bool detail = playlist_check_translate_song(*song, base_uri,
+								  loader);
+		if (!filter->Match(static_cast<LightSong>(*song)))
+			continue;
+
+		if (skip > 0) {
+			--skip;
+			continue;
+		}
+
+		if (detail)
+			song_print_info(r, *song);
+		else
+			/* fallback if no detail was requested or no
+			   detail was available */
+			song_print_uri(r, *song);
+
+		if (--n == 0)
+			break;
+	}
+}
+
 void
 playlist_file_print(Response &r, Partition &partition,
 		    const SongLoader &loader,
 		    const LocatedUri &uri,
 		    unsigned start_index,
 		    unsigned end_index,
-		    bool detail)
+		    bool detail,
+		    SongFilter *filter)
 try {
 	Mutex mutex;
 
@@ -72,8 +116,12 @@ try {
 	if (playlist == nullptr)
 		throw PlaylistError::NoSuchList();
 
-	playlist_provider_print(r, loader, uri.canonical_uri, *playlist,
-				start_index, end_index, detail);
+	if (filter == nullptr)
+		playlist_provider_print(r, loader, uri.canonical_uri, *playlist,
+					start_index, end_index, detail);
+	else
+		playlist_provider_search_print(r, loader, uri.canonical_uri, *playlist,
+					start_index, end_index, filter);
 } catch (...) {
 	if (IsFileNotFound(std::current_exception()))
 		throw PlaylistError::NoSuchList();

src/playlist/Print.hxx

@@ -5,6 +5,7 @@
 
 class Response;
 class SongLoader;
+class SongFilter;
 struct Partition;
 
 /**
@@ -20,4 +21,6 @@ playlist_file_print(Response &r, Partition &partition,
 		    const SongLoader &loader,
 		    const LocatedUri &uri,
 		    unsigned start_index, unsigned end_index,
-		    bool detail);
+		    bool detail,
+		    SongFilter *filter);
+