playlist/memory: use std::forward_list instead of GSList

Makefile.am

@@ -269,6 +269,7 @@ src_mpd_SOURCES = \
 	src/string_util.c \
 	src/Volume.cxx src/Volume.hxx \
 	src/SongFilter.cxx src/SongFilter.hxx \
+	src/SongPointer.hxx \
 	src/PlaylistFile.cxx src/PlaylistFile.hxx \
 	src/timer.c
 

src/SongPointer.hxx

+/*
+ * Copyright (C) 2003-2013 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef MPD_SONG_POINTER_HXX
+#define MPD_SONG_POINTER_HXX
+
+#include "song.h"
+
+#include <utility>
+
+class SongPointer {
+	struct song *song;
+
+public:
+	explicit SongPointer(struct song *_song)
+		:song(_song) {}
+
+	SongPointer(const SongPointer &) = delete;
+
+	SongPointer(SongPointer &&other):song(other.song) {
+		other.song = nullptr;
+	}
+
+	~SongPointer() {
+		if (song != nullptr)
+			song_free(song);
+	}
+
+	SongPointer &operator=(const SongPointer &) = delete;
+
+	SongPointer &operator=(SongPointer &&other) {
+		std::swap(song, other.song);
+		return *this;
+	}
+
+	operator const struct song *() const {
+		return song;
+	}
+
+	struct song *Steal() {
+		auto result = song;
+		song = nullptr;
+		return result;
+	}
+};
+
+#endif

src/playlist/AsxPlaylistPlugin.cxx

@@ -40,7 +40,7 @@ struct AsxParser {
 	 * The list of songs (in reverse order because that's faster
 	 * while adding).
 	 */
-	GSList *songs;
+	std::forward_list<SongPointer> songs;
 
 	/**
 	 * The current position in the XML file.
@@ -63,8 +63,7 @@ struct AsxParser {
 	struct song *song;
 
 	AsxParser()
-		:songs(nullptr),
-		 state(ROOT) {}
+		:state(ROOT) {}
 
 };
 
@@ -144,8 +143,7 @@ asx_end_element(G_GNUC_UNUSED GMarkupParseContext *context,
 	case AsxParser::ENTRY:
 		if (g_ascii_strcasecmp(element_name, "entry") == 0) {
 			if (strcmp(parser->song->uri, "asx:") != 0)
-				parser->songs = g_slist_prepend(parser->songs,
-								parser->song);
+				parser->songs.emplace_front(parser->song);
 			else
 				song_free(parser->song);
 
@@ -189,23 +187,12 @@ static const GMarkupParser asx_parser = {
 };
 
 static void
-song_free_callback(gpointer data, G_GNUC_UNUSED gpointer user_data)
-{
-	struct song *song = (struct song *)data;
-
-	song_free(song);
-}
-
-static void
 asx_parser_destroy(gpointer data)
 {
 	AsxParser *parser = (AsxParser *)data;
 
 	if (parser->state >= AsxParser::ENTRY)
 		song_free(parser->song);
-
-	g_slist_foreach(parser->songs, song_free_callback, NULL);
-	g_slist_free(parser->songs);
 }
 
 /*
@@ -261,11 +248,9 @@ asx_open_stream(struct input_stream *is)
 		return NULL;
 	}
 
-	/* create a #AsxPlaylist object from the parsed song list */
-
+	parser.songs.reverse();
 	MemoryPlaylistProvider *playlist =
-		new MemoryPlaylistProvider(g_slist_reverse(parser.songs));
-	parser.songs = NULL;
+		new MemoryPlaylistProvider(std::move(parser.songs));
 
 	g_markup_parse_context_free(context);
 

src/playlist/DespotifyPlaylistPlugin.cxx

@@ -35,7 +35,8 @@ extern "C" {
 
 struct despotify_playlist {
 	struct despotify_session *session;
-	GSList *list;
+
+	std::forward_list<SongPointer> songs;
 };
 
 static void
@@ -59,7 +60,7 @@ add_song(struct despotify_playlist *ctx, struct ds_track *track)
 	song = song_remote_new(uri);
 	song->tag = mpd_despotify_tag_from_track(track);
 
-	ctx->list = g_slist_prepend(ctx->list, song);
+	ctx->songs.emplace_front(song);
 }
 
 static bool
@@ -115,17 +116,16 @@ despotify_playlist_open_uri(const char *url,
 
 	session = mpd_despotify_get_session();
 	if (!session)
-		goto clean_none;
+		return nullptr;
 
 	/* Get link without spt:// */
 	link = despotify_link_from_uri(url + strlen(despotify_playlist_plugin.schemes[0]) + 3);
 	if (!link) {
 		g_debug("Can't find %s\n", url);
-		goto clean_none;
+		return nullptr;
 	}
 
 	struct despotify_playlist ctx;
-	ctx.list = nullptr;
 	ctx.session = session;
 
 	switch (link->type)
@@ -142,15 +142,10 @@ despotify_playlist_open_uri(const char *url,
 	}
 	despotify_free_link(link);
 	if (!parse_result)
-		goto clean_playlist;
-
-	return new MemoryPlaylistProvider(g_slist_reverse(ctx.list));
-
-clean_playlist:
-	g_slist_free(ctx.list);
-clean_none:
+		return nullptr;
 
-	return nullptr;
+	ctx.songs.reverse();
+	return new MemoryPlaylistProvider(std::move(ctx.songs));
 }
 
 static const char *const despotify_schemes[] = {

src/playlist/MemoryPlaylistProvider.cxx

@@ -52,33 +52,18 @@ static constexpr struct playlist_plugin memory_playlist_plugin = {
 	nullptr,
 };
 
-MemoryPlaylistProvider::MemoryPlaylistProvider(GSList *_songs)
-	:songs(_songs) {
+MemoryPlaylistProvider::MemoryPlaylistProvider(std::forward_list<SongPointer> &&_songs)
+	:songs(std::move(_songs)) {
 	playlist_provider_init(this, &memory_playlist_plugin);
 }
 
-static void
-song_free_callback(gpointer data, G_GNUC_UNUSED gpointer user_data)
-{
-	struct song *song = (struct song *)data;
-
-	song_free(song);
-}
-
-MemoryPlaylistProvider::~MemoryPlaylistProvider()
-{
-	g_slist_foreach(songs, song_free_callback, NULL);
-	g_slist_free(songs);
-}
-
 inline song *
 MemoryPlaylistProvider::Read()
 {
-	if (songs == nullptr)
-		return nullptr;
+	if (songs.empty())
+		return NULL;
 
-	song *result = (song *)songs->data;
-	songs = g_slist_remove(songs, result);
+	auto result = songs.front().Steal();
+	songs.pop_front();
 	return result;
 }
-

src/playlist/MemoryPlaylistProvider.hxx

@@ -21,17 +21,17 @@
 #define MPD_MEMORY_PLAYLIST_PROVIDER_HXX
 
 #include "PlaylistPlugin.hxx"
+#include "SongPointer.hxx"
 
-#include <glib.h>
+#include <forward_list>
 
 struct song;
 
 class MemoryPlaylistProvider : public playlist_provider {
-	GSList *songs;
+	std::forward_list<SongPointer> songs;
 
 public:
-	MemoryPlaylistProvider(GSList *_songs);
-	~MemoryPlaylistProvider();
+	MemoryPlaylistProvider(std::forward_list<SongPointer> &&_songs);
 
 	song *Read();
 };

src/playlist/PlsPlaylistPlugin.cxx

@@ -27,11 +27,8 @@
 
 #include <glib.h>
 
-struct PlsPlaylist {
-	GSList *songs;
-};
-
-static void pls_parser(GKeyFile *keyfile, PlsPlaylist *playlist)
+static void
+pls_parser(GKeyFile *keyfile, std::forward_list<SongPointer> &songs)
 {
 	gchar *key;
 	gchar *value;
@@ -96,7 +93,7 @@ static void pls_parser(GKeyFile *keyfile, PlsPlaylist *playlist)
 		if(error) g_error_free(error);
 		error = NULL;
 
-		playlist->songs = g_slist_prepend(playlist->songs, song);
+		songs.emplace_front(song);
 		num_entries--;
 	}
 
@@ -150,13 +147,12 @@ pls_open_stream(struct input_stream *is)
 		return NULL;
 	}
 
-	PlsPlaylist playlist;
-	playlist.songs = nullptr;
-
-	pls_parser(keyfile, &playlist);
+	std::forward_list<SongPointer> songs;
+	pls_parser(keyfile, songs);
 	g_key_file_free(keyfile);
 
-	return new MemoryPlaylistProvider(g_slist_reverse(playlist.songs));
+	songs.reverse();
+	return new MemoryPlaylistProvider(std::move(songs));
 }
 
 static const char *const pls_suffixes[] = {

src/playlist/RssPlaylistPlugin.cxx

@@ -40,7 +40,7 @@ struct RssParser {
 	 * The list of songs (in reverse order because that's faster
 	 * while adding).
 	 */
-	GSList *songs;
+	std::forward_list<SongPointer> songs;
 
 	/**
 	 * The current position in the XML file.
@@ -63,7 +63,7 @@ struct RssParser {
 	struct song *song;
 
 	RssParser()
-		:songs(nullptr), state(ROOT) {}
+		:state(ROOT) {}
 };
 
 static const gchar *
@@ -140,8 +140,7 @@ rss_end_element(G_GNUC_UNUSED GMarkupParseContext *context,
 	case RssParser::ITEM:
 		if (g_ascii_strcasecmp(element_name, "item") == 0) {
 			if (strcmp(parser->song->uri, "rss:") != 0)
-				parser->songs = g_slist_prepend(parser->songs,
-								parser->song);
+				parser->songs.emplace_front(parser->song);
 			else
 				song_free(parser->song);
 
@@ -185,23 +184,12 @@ static const GMarkupParser rss_parser = {
 };
 
 static void
-song_free_callback(gpointer data, G_GNUC_UNUSED gpointer user_data)
-{
-	struct song *song = (struct song *)data;
-
-	song_free(song);
-}
-
-static void
 rss_parser_destroy(gpointer data)
 {
 	RssParser *parser = (RssParser *)data;
 
 	if (parser->state >= RssParser::ITEM)
 		song_free(parser->song);
-
-	g_slist_foreach(parser->songs, song_free_callback, NULL);
-	g_slist_free(parser->songs);
 }
 
 /*
@@ -257,11 +245,9 @@ rss_open_stream(struct input_stream *is)
 		return NULL;
 	}
 
-	/* create a #rss_playlist object from the parsed song list */
-
+	parser.songs.reverse();
 	MemoryPlaylistProvider *playlist =
-		new MemoryPlaylistProvider(g_slist_reverse(parser.songs));
-	parser.songs = NULL;
+		new MemoryPlaylistProvider(std::move(parser.songs));
 
 	g_markup_parse_context_free(context);
 

src/playlist/SoundCloudPlaylistPlugin.cxx

@@ -101,7 +101,8 @@ struct parse_data {
 	long duration;
 	char* title;
 	int got_url; /* nesting level of last stream_url */
-	GSList* songs;
+
+	std::forward_list<SongPointer> songs;
 };
 
 static int handle_integer(void *ctx,
@@ -215,7 +216,7 @@ static int handle_end_map(void *ctx)
 		tag_add_item(t, TAG_NAME, data->title);
 	s->tag = t;
 
-	data->songs = g_slist_prepend(data->songs, s);
+	data->songs.emplace_front(s);
 
 	return 1;
 }
@@ -370,7 +371,6 @@ soundcloud_open_uri(const char *uri, Mutex &mutex, Cond &cond)
 	struct parse_data data;
 
 	data.got_url = 0;
-	data.songs = NULL;
 	data.title = NULL;
 	data.stream_url = NULL;
 #ifdef HAVE_YAJL1
@@ -391,7 +391,8 @@ soundcloud_open_uri(const char *uri, Mutex &mutex, Cond &cond)
 	if (ret == -1)
 		return NULL;
 
-	return new MemoryPlaylistProvider(g_slist_reverse(data.songs));
+	data.songs.reverse();
+	return new MemoryPlaylistProvider(std::move(data.songs));
 }
 
 static const char *const soundcloud_schemes[] = {

src/playlist/XspfPlaylistPlugin.cxx

@@ -22,7 +22,6 @@
 #include "MemoryPlaylistProvider.hxx"
 #include "input_stream.h"
 #include "uri.h"
-#include "song.h"
 #include "tag.h"
 
 #include <glib.h>
@@ -41,7 +40,7 @@ struct XspfParser {
 	 * The list of songs (in reverse order because that's faster
 	 * while adding).
 	 */
-	GSList *songs;
+	std::forward_list<SongPointer> songs;
 
 	/**
 	 * The current position in the XML file.
@@ -65,7 +64,7 @@ struct XspfParser {
 	struct song *song;
 
 	XspfParser()
-		:songs(nullptr), state(ROOT) {}
+		:state(ROOT) {}
 };
 
 static void
@@ -148,8 +147,7 @@ xspf_end_element(G_GNUC_UNUSED GMarkupParseContext *context,
 	case XspfParser::TRACK:
 		if (strcmp(element_name, "track") == 0) {
 			if (parser->song != NULL)
-				parser->songs = g_slist_prepend(parser->songs,
-								parser->song);
+				parser->songs.emplace_front(parser->song);
 
 			parser->state = XspfParser::TRACKLIST;
 		} else
@@ -207,23 +205,12 @@ static const GMarkupParser xspf_parser = {
 };
 
 static void
-song_free_callback(gpointer data, G_GNUC_UNUSED gpointer user_data)
-{
-	struct song *song = (struct song *)data;
-
-	song_free(song);
-}
-
-static void
 xspf_parser_destroy(gpointer data)
 {
 	XspfParser *parser = (XspfParser *)data;
 
 	if (parser->state >= XspfParser::TRACK && parser->song != NULL)
 		song_free(parser->song);
-
-	g_slist_foreach(parser->songs, song_free_callback, NULL);
-	g_slist_free(parser->songs);
 }
 
 /*
@@ -279,11 +266,9 @@ xspf_open_stream(struct input_stream *is)
 		return NULL;
 	}
 
-	/* create a #xspf_playlist object from the parsed song list */
-
+	parser.songs.reverse();
 	MemoryPlaylistProvider *playlist =
-		new MemoryPlaylistProvider(g_slist_reverse(parser.songs));
-	parser.songs = NULL;
+		new MemoryPlaylistProvider(std::move(parser.songs));
 
 	g_markup_parse_context_free(context);