fs/Traits: GetParent() returns std::string_view

src/command/FileCommands.cxx

@@ -169,7 +169,7 @@ handle_read_comments(Client &client, Request args, Response &r)
  * opened file or #nullptr on failure.
  */
 static InputStreamPtr
-find_stream_art(const char *directory, Mutex &mutex)
+find_stream_art(std::string_view directory, Mutex &mutex)
 {
 	static constexpr char const * art_names[] = {
 		"cover.png",
@@ -195,11 +195,11 @@ find_stream_art(const char *directory, Mutex &mutex)
 static CommandResult
 read_stream_art(Response &r, const char *uri, size_t offset)
 {
-	std::string art_directory = PathTraitsUTF8::GetParent(uri);
+	const auto art_directory = PathTraitsUTF8::GetParent(uri);
 
 	Mutex mutex;
 
-	InputStreamPtr is = find_stream_art(art_directory.c_str(), mutex);
+	InputStreamPtr is = find_stream_art(art_directory, mutex);
 
 	if (is == nullptr) {
 		r.Error(ACK_ERROR_NO_EXIST, "No file exists");

src/fs/Traits.cxx

@@ -64,7 +64,7 @@ GetBasePathImpl(typename Traits::const_pointer p) noexcept
 }
 
 template<typename Traits>
-typename Traits::string
+typename Traits::string_view
 GetParentPathImpl(typename Traits::const_pointer p) noexcept
 {
 #if !CLANG_CHECK_VERSION(3,6)
@@ -81,7 +81,7 @@ GetParentPathImpl(typename Traits::const_pointer p) noexcept
 	if (Traits::IsDrive(p) && sep == p + 2)
 		return {p, 3u};
 #endif
-	return {p, sep};
+	return {p, size_t(sep - p)};
 }
 
 template<typename Traits>
@@ -130,7 +130,7 @@ PathTraitsFS::GetBase(PathTraitsFS::const_pointer p) noexcept
 	return GetBasePathImpl<PathTraitsFS>(p);
 }
 
-PathTraitsFS::string
+PathTraitsFS::string_view
 PathTraitsFS::GetParent(PathTraitsFS::const_pointer p) noexcept
 {
 	return GetParentPathImpl<PathTraitsFS>(p);
@@ -168,7 +168,7 @@ PathTraitsUTF8::GetBase(const_pointer p) noexcept
 	return GetBasePathImpl<PathTraitsUTF8>(p);
 }
 
-PathTraitsUTF8::string
+PathTraitsUTF8::string_view
 PathTraitsUTF8::GetParent(const_pointer p) noexcept
 {
 	return GetParentPathImpl<PathTraitsUTF8>(p);

src/fs/Traits.hxx

@@ -138,7 +138,7 @@ struct PathTraitsFS {
 	 * separator in the given input string.
 	 */
 	gcc_pure gcc_nonnull_all
-	static string GetParent(const_pointer p) noexcept;
+	static string_view GetParent(const_pointer p) noexcept;
 
 	/**
 	 * Determine the relative part of the given path to this
@@ -247,7 +247,7 @@ struct PathTraitsUTF8 {
 	 * separator in the given input string.
 	 */
 	gcc_pure gcc_nonnull_all
-	static string GetParent(const_pointer p) noexcept;
+	static string_view GetParent(const_pointer p) noexcept;
 
 	/**
 	 * Determine the relative part of the given path to this

src/playlist/PlaylistQueue.cxx

@@ -41,9 +41,9 @@ playlist_load_into_queue(const char *uri, SongEnumerator &e,
 			 playlist &dest, PlayerControl &pc,
 			 const SongLoader &loader)
 {
-	const std::string base_uri = uri != nullptr
+	const auto base_uri = uri != nullptr
 		? PathTraitsUTF8::GetParent(uri)
-		: std::string(".");
+		: ".";
 
 	std::unique_ptr<DetachedSong> song;
 	for (unsigned i = 0;
@@ -54,7 +54,7 @@ playlist_load_into_queue(const char *uri, SongEnumerator &e,
 			continue;
 		}
 
-		if (!playlist_check_translate_song(*song, base_uri.c_str(),
+		if (!playlist_check_translate_song(*song, base_uri,
 						   loader)) {
 			continue;
 		}

src/playlist/Print.cxx

@@ -36,13 +36,13 @@ playlist_provider_print(Response &r,
 			const char *uri,
 			SongEnumerator &e, bool detail) noexcept
 {
-	const std::string base_uri = uri != nullptr
+	const auto base_uri = uri != nullptr
 		? PathTraitsUTF8::GetParent(uri)
-		: std::string(".");
+		: ".";
 
 	std::unique_ptr<DetachedSong> song;
 	while ((song = e.NextSong()) != nullptr) {
-		if (playlist_check_translate_song(*song, base_uri.c_str(),
+		if (playlist_check_translate_song(*song, base_uri,
 						  loader) &&
 		    detail)
 			song_print_info(r, *song);