1 files changed, 214 insertions, 0 deletions
diff --git a/src/filter/ChainFilterPlugin.cxx b/src/filter/ChainFilterPlugin.cxx
new file mode 100644
index 000000000..51eb4b6f6
--- /dev/null
+++ b/src/filter/ChainFilterPlugin.cxx
@@ -0,0 +1,214 @@
+/*
+ * 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.
+ */
+
+#include "config.h"
+#include "ChainFilterPlugin.hxx"
+#include "conf.h"
+#include "FilterPlugin.hxx"
+#include "FilterInternal.hxx"
+#include "FilterRegistry.hxx"
+#include "audio_format.h"
+
+#include <glib.h>
+
+#include <assert.h>
+
+struct ChainFilter {
+	/** the base class */
+	struct filter base;
+
+	GSList *children;
+
+	ChainFilter():children(nullptr) {
+		filter_init(&base, &chain_filter_plugin);
+	}
+};
+
+static inline GQuark
+filter_quark(void)
+{
+	return g_quark_from_static_string("filter");
+}
+
+static struct filter *
+chain_filter_init(G_GNUC_UNUSED const struct config_param *param,
+		  G_GNUC_UNUSED GError **error_r)
+{
+	ChainFilter *chain = new ChainFilter();
+
+	return &chain->base;
+}
+
+static void
+chain_free_child(gpointer data, G_GNUC_UNUSED gpointer user_data)
+{
+	struct filter *filter = (struct filter *)data;
+
+	filter_free(filter);
+}
+
+static void
+chain_filter_finish(struct filter *_filter)
+{
+	ChainFilter *chain = (ChainFilter *)_filter;
+
+	g_slist_foreach(chain->children, chain_free_child, NULL);
+	g_slist_free(chain->children);
+
+	delete chain;
+}
+
+/**
+ * Close all filters in the chain until #until is reached.  #until
+ * itself is not closed.
+ */
+static void
+chain_close_until(ChainFilter *chain, const struct filter *until)
+{
+	GSList *i = chain->children;
+
+	while (true) {
+		/* this assertion fails if #until does not exist
+		   (anymore) */
+		assert(i != NULL);
+
+		if (i->data == until)
+			/* don't close this filter */
+			break;
+
+		/* close this filter */
+		struct filter *filter = (struct filter *)i->data;
+		filter_close(filter);
+
+		i = g_slist_next(i);
+	}
+}
+
+static const struct audio_format *
+chain_open_child(struct filter *filter,
+		 const struct audio_format *prev_audio_format,
+		 GError **error_r)
+{
+	struct audio_format conv_audio_format = *prev_audio_format;
+	const struct audio_format *next_audio_format;
+
+	next_audio_format = filter_open(filter, &conv_audio_format, error_r);
+	if (next_audio_format == NULL)
+		return NULL;
+
+	if (!audio_format_equals(&conv_audio_format, prev_audio_format)) {
+		struct audio_format_string s;
+
+		filter_close(filter);
+		g_set_error(error_r, filter_quark(), 0,
+			    "Audio format not supported by filter '%s': %s",
+			    filter->plugin->name,
+			    audio_format_to_string(prev_audio_format, &s));
+		return NULL;
+	}
+
+	return next_audio_format;
+}
+
+static const struct audio_format *
+chain_filter_open(struct filter *_filter, struct audio_format *in_audio_format,
+		  GError **error_r)
+{
+	ChainFilter *chain = (ChainFilter *)_filter;
+	const struct audio_format *audio_format = in_audio_format;
+
+	for (GSList *i = chain->children; i != NULL; i = g_slist_next(i)) {
+		struct filter *filter = (struct filter *)i->data;
+
+		audio_format = chain_open_child(filter, audio_format, error_r);
+		if (audio_format == NULL) {
+			/* rollback, close all children */
+			chain_close_until(chain, filter);
+			return NULL;
+		}
+	}
+
+	/* return the output format of the last filter */
+	return audio_format;
+}
+
+static void
+chain_close_child(gpointer data, G_GNUC_UNUSED gpointer user_data)
+{
+	struct filter *filter = (struct filter *)data;
+
+	filter_close(filter);
+}
+
+static void
+chain_filter_close(struct filter *_filter)
+{
+	ChainFilter *chain = (ChainFilter *)_filter;
+
+	g_slist_foreach(chain->children, chain_close_child, NULL);
+}
+
+static const void *
+chain_filter_filter(struct filter *_filter,
+		    const void *src, size_t src_size,
+		    size_t *dest_size_r, GError **error_r)
+{
+	ChainFilter *chain = (ChainFilter *)_filter;
+
+	for (GSList *i = chain->children; i != NULL; i = g_slist_next(i)) {
+		struct filter *filter = (struct filter *)i->data;
+
+		/* feed the output of the previous filter as input
+		   into the current one */
+		src = filter_filter(filter, src, src_size, &src_size, error_r);
+		if (src == NULL)
+			return NULL;
+	}
+
+	/* return the output of the last filter */
+	*dest_size_r = src_size;
+	return src;
+}
+
+const struct filter_plugin chain_filter_plugin = {
+	"chain",
+	chain_filter_init,
+	chain_filter_finish,
+	chain_filter_open,
+	chain_filter_close,
+	chain_filter_filter,
+};
+
+struct filter *
+filter_chain_new(void)
+{
+	struct filter *filter = filter_new(&chain_filter_plugin, NULL, NULL);
+	/* chain_filter_init() never fails */
+	assert(filter != NULL);
+
+	return filter;
+}
+
+void
+filter_chain_append(struct filter *_chain, struct filter *filter)
+{
+	ChainFilter *chain = (ChainFilter *)_chain;
+
+	chain->children = g_slist_append(chain->children, filter);
+}