1 files changed, 184 insertions, 0 deletions
diff --git a/src/filter/ChainFilterPlugin.cxx b/src/filter/ChainFilterPlugin.cxx
new file mode 100644
index 00000000..c8666615
--- /dev/null
+++ b/src/filter/ChainFilterPlugin.cxx
@@ -0,0 +1,184 @@
+/*
+ * 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 <list>
+
+#include <assert.h>
+
+class ChainFilter final : public Filter {
+	struct Child {
+		const char *name;
+		Filter *filter;
+
+		Child(const char *_name, Filter *_filter)
+			:name(_name), filter(_filter) {}
+		~Child() {
+			delete filter;
+		}
+
+		Child(const Child &) = delete;
+		Child &operator=(const Child &) = delete;
+	};
+
+	std::list<Child> children;
+
+public:
+	void Append(const char *name, Filter *filter) {
+		children.emplace_back(name, filter);
+	}
+
+	virtual const audio_format *Open(audio_format &af, GError **error_r);
+	virtual void Close();
+	virtual const void *FilterPCM(const void *src, size_t src_size,
+				      size_t *dest_size_r, GError **error_r);
+
+private:
+	/**
+	 * Close all filters in the chain until #until is reached.
+	 * #until itself is not closed.
+	 */
+	void CloseUntil(const Filter *until);
+};
+
+static inline GQuark
+filter_quark(void)
+{
+	return g_quark_from_static_string("filter");
+}
+
+static Filter *
+chain_filter_init(gcc_unused const struct config_param *param,
+		  gcc_unused GError **error_r)
+{
+	return new ChainFilter();
+}
+
+void
+ChainFilter::CloseUntil(const Filter *until)
+{
+	for (auto &child : children) {
+		if (child.filter == until)
+			/* don't close this filter */
+			return;
+
+		/* close this filter */
+		child.filter->Close();
+	}
+
+	/* this assertion fails if #until does not exist (anymore) */
+	assert(false);
+}
+
+static const struct audio_format *
+chain_open_child(const char *name, Filter *filter,
+		 const audio_format &prev_audio_format,
+		 GError **error_r)
+{
+	audio_format conv_audio_format = prev_audio_format;
+	const audio_format *next_audio_format =
+		filter->Open(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();
+		g_set_error(error_r, filter_quark(), 0,
+			    "Audio format not supported by filter '%s': %s",
+			    name,
+			    audio_format_to_string(&prev_audio_format, &s));
+		return NULL;
+	}
+
+	return next_audio_format;
+}
+
+const audio_format *
+ChainFilter::Open(audio_format &in_audio_format, GError **error_r)
+{
+	const audio_format *audio_format = &in_audio_format;
+
+	for (auto &child : children) {
+		audio_format = chain_open_child(child.name, child.filter,
+						*audio_format, error_r);
+		if (audio_format == NULL) {
+			/* rollback, close all children */
+			CloseUntil(child.filter);
+			return NULL;
+		}
+	}
+
+	/* return the output format of the last filter */
+	return audio_format;
+}
+
+void
+ChainFilter::Close()
+{
+	for (auto &child : children)
+		child.filter->Close();
+}
+
+const void *
+ChainFilter::FilterPCM(const void *src, size_t src_size,
+		       size_t *dest_size_r, GError **error_r)
+{
+	for (auto &child : children) {
+		/* feed the output of the previous filter as input
+		   into the current one */
+		src = child.filter->FilterPCM(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,
+};
+
+Filter *
+filter_chain_new(void)
+{
+	return new ChainFilter();
+}
+
+void
+filter_chain_append(Filter &_chain, const char *name, Filter *filter)
+{
+	ChainFilter &chain = (ChainFilter &)_chain;
+
+	chain.Append(name, filter);
+}