filter/AutoConvert: move the Filter class to TwoFilters.cxx

src/filter/plugins/AutoConvertFilterPlugin.cxx

@@ -19,6 +19,7 @@
 
 #include "AutoConvertFilterPlugin.hxx"
 #include "ConvertFilterPlugin.hxx"
+#include "TwoFilters.hxx"
 #include "filter/Filter.hxx"
 #include "filter/Prepared.hxx"
 #include "pcm/AudioFormat.hxx"
@@ -27,33 +28,6 @@
 #include <cassert>
 #include <memory>
 
-class AutoConvertFilter final : public Filter {
-	/**
-	 * The underlying filter.
-	 */
-	std::unique_ptr<Filter> filter;
-
-	/**
-	 * A convert_filter, just in case conversion is needed.  nullptr
-	 * if unused.
-	 */
-	std::unique_ptr<Filter> convert;
-
-public:
-	AutoConvertFilter(std::unique_ptr<Filter> &&_filter,
-			  std::unique_ptr<Filter> &&_convert)
-		:Filter(_filter->GetOutAudioFormat()),
-		 filter(std::move(_filter)), convert(std::move(_convert)) {}
-
-	void Reset() noexcept override {
-		filter->Reset();
-		convert->Reset();
-	}
-
-	ConstBuffer<void> FilterPCM(ConstBuffer<void> src) override;
-	ConstBuffer<void> Flush() override;
-};
-
 class PreparedAutoConvertFilter final : public PreparedFilter {
 	/**
 	 * The underlying filter.
@@ -88,25 +62,8 @@ PreparedAutoConvertFilter::Open(AudioFormat &in_audio_format)
 	auto convert = convert_filter_new(in_audio_format,
 					  child_audio_format);
 
-	return std::make_unique<AutoConvertFilter>(std::move(new_filter),
+	return std::make_unique<TwoFilters>(std::move(convert),
-						   std::move(convert));
+					    std::move(new_filter));
-}
-
-ConstBuffer<void>
-AutoConvertFilter::FilterPCM(ConstBuffer<void> src)
-{
-	src = convert->FilterPCM(src);
-	return filter->FilterPCM(src);
-}
-
-ConstBuffer<void>
-AutoConvertFilter::Flush()
-{
-	auto result = convert->Flush();
-	if (!result.IsNull())
-		return filter->FilterPCM(result);
-
-	return filter->Flush();
 }
 
 std::unique_ptr<PreparedFilter>

src/filter/plugins/TwoFilters.cxx

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2003-2020 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 "TwoFilters.hxx"
+#include "util/ConstBuffer.hxx"
+
+ConstBuffer<void>
+TwoFilters::FilterPCM(ConstBuffer<void> src)
+{
+	return second->FilterPCM(first->FilterPCM(src));
+}
+
+ConstBuffer<void>
+TwoFilters::Flush()
+{
+	auto result = first->Flush();
+	if (!result.IsNull())
+		/* Flush() output from the first Filter must be
+		   filtered by the second Filter */
+		return second->FilterPCM(result);
+
+	return second->Flush();
+}

src/filter/plugins/TwoFilters.hxx

@@ -0,0 +1,49 @@
+/*
+ * Copyright 2003-2020 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_WITH_CONVERT_FILTER_HXX
+#define MPD_WITH_CONVERT_FILTER_HXX
+
+#include "filter/Filter.hxx"
+
+#include <memory>
+
+/**
+ * A #Filter implementation which chains two other filters.
+ */
+class TwoFilters final : public Filter {
+	std::unique_ptr<Filter> first, second;
+
+public:
+	template<typename F, typename S>
+	TwoFilters(F &&_first, S &&_second) noexcept
+		:Filter(_second->GetOutAudioFormat()),
+		 first(std::forward<F>(_first)),
+		 second(std::forward<S>(_second)) {}
+
+	void Reset() noexcept override {
+		first->Reset();
+		second->Reset();
+	}
+
+	ConstBuffer<void> FilterPCM(ConstBuffer<void> src) override;
+	ConstBuffer<void> Flush() override;
+};
+
+#endif

src/filter/plugins/meson.build

@@ -14,6 +14,7 @@ filter_plugins = static_library(
   'filter_plugins',
   '../../AudioCompress/compress.c',
   'NullFilterPlugin.cxx',
+  'TwoFilters.cxx',
   'ChainFilterPlugin.cxx',
   'AutoConvertFilterPlugin.cxx',
   'ConvertFilterPlugin.cxx',