song/AudioFormatSongFilter: new filter type

Makefile.am

@@ -1036,6 +1036,7 @@ libsong_a_SOURCES = \
 	src/song/BaseSongFilter.cxx src/song/BaseSongFilter.hxx \
 	src/song/TagSongFilter.cxx src/song/TagSongFilter.hxx \
 	src/song/ModifiedSinceSongFilter.cxx src/song/ModifiedSinceSongFilter.hxx \
+	src/song/AudioFormatSongFilter.cxx src/song/AudioFormatSongFilter.hxx \
 	src/song/AndSongFilter.cxx src/song/AndSongFilter.hxx \
 	src/song/Filter.cxx src/song/Filter.hxx \
 	src/song/LightSong.cxx src/song/LightSong.hxx
@@ -1932,6 +1933,7 @@ endif
 
 test_ParseSongFilter_LDADD = \
 	libsong.a \
+	libpcm.a \
 	$(TAG_LIBS) \
 	$(ICU_LDADD) \
 	libutil.a

doc/protocol.xml

@@ -271,6 +271,13 @@
 
         <listitem>
           <para>
+            "<code>(AudioFormat == 'SAMPLERATE:BITS:CHANNELS')</code>":
+            compares the audio format with the given value.
+          </para>
+        </listitem>
+
+        <listitem>
+          <para>
             "<code>EXPRESSION1 AND EXPRESSION2 ...</code>": combine two or
             more expressions with logical "and".
           </para>

src/song/AudioFormatSongFilter.cxx

+/*
+ * Copyright 2003-2018 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 "AudioFormatSongFilter.hxx"
+#include "LightSong.hxx"
+#include "util/StringBuffer.hxx"
+
+std::string
+AudioFormatSongFilter::ToExpression() const noexcept
+{
+	// TODO: support mask
+	return std::string("(AudioFormat == \"") + ToString(value).c_str() + "\")";
+}
+
+bool
+AudioFormatSongFilter::Match(const LightSong &song) const noexcept
+{
+	// TODO: support mask
+	return song.audio_format == value;
+}

src/song/AudioFormatSongFilter.hxx

+/*
+ * Copyright 2003-2018 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_AUDIO_FORMAT_SONG_FILTER_HXX
+#define MPD_AUDIO_FORMAT_SONG_FILTER_HXX
+
+#include "ISongFilter.hxx"
+#include "AudioFormat.hxx"
+
+class AudioFormatSongFilter final : public ISongFilter {
+	AudioFormat value;
+
+public:
+	explicit AudioFormatSongFilter(const AudioFormat &_value) noexcept
+		:value(_value) {}
+
+
+	/* virtual methods from ISongFilter */
+	ISongFilterPtr Clone() const noexcept override {
+		return std::make_unique<AudioFormatSongFilter>(*this);
+	}
+
+	std::string ToExpression() const noexcept override;
+	bool Match(const LightSong &song) const noexcept override;
+};
+
+#endif

src/song/Filter.cxx

@@ -23,7 +23,9 @@
 #include "BaseSongFilter.hxx"
 #include "TagSongFilter.hxx"
 #include "ModifiedSinceSongFilter.hxx"
+#include "AudioFormatSongFilter.hxx"
 #include "LightSong.hxx"
+#include "AudioParser.hxx"
 #include "tag/ParseName.hxx"
 #include "tag/Tag.hxx"
 #include "util/CharUtil.hxx"
@@ -55,6 +57,7 @@ enum {
 	LOCATE_TAG_BASE_TYPE = TAG_NUM_OF_ITEM_TYPES + 1,
 
 	LOCATE_TAG_MODIFIED_SINCE,
+	LOCATE_TAG_AUDIO_FORMAT,
 	LOCATE_TAG_FILE_TYPE,
 	LOCATE_TAG_ANY_TYPE,
 };
@@ -79,6 +82,9 @@ locate_parse_type(const char *str) noexcept
 	if (strcmp(str, "modified-since") == 0)
 		return LOCATE_TAG_MODIFIED_SINCE;
 
+	if (StringEqualsCaseASCII(str, "AudioFormat"))
+		return LOCATE_TAG_AUDIO_FORMAT;
+
 	return tag_name_parse_i(str);
 }
 
@@ -223,6 +229,21 @@ SongFilter::ParseExpression(const char *&s, bool fold_case)
 		s = StripLeft(s + 1);
 
 		return std::make_unique<BaseSongFilter>(std::move(value));
+	} else if (type == LOCATE_TAG_AUDIO_FORMAT) {
+		if (s[0] != '=' || s[1] != '=')
+			throw std::runtime_error("'==' expected");
+
+		s = StripLeft(s + 2);
+
+		// TODO: support mask
+		const auto value = ParseAudioFormat(ExpectQuoted(s).c_str(),
+						    false);
+
+		if (*s != ')')
+			throw std::runtime_error("')' expected");
+		s = StripLeft(s + 1);
+
+		return std::make_unique<AudioFormatSongFilter>(value);
 	} else {
 		bool negated = false;
 		if (s[0] == '!' && s[1] == '=')