tag/ReplayGain: add VorbisComment parser

Move code from the Vorbis and FLAC decoder plugins.

src/decoder/plugins/FlacMetadata.cxx

@@ -26,6 +26,7 @@
 #include "tag/TagBuilder.hxx"
 #include "tag/Tag.hxx"
 #include "tag/VorbisComment.hxx"
+#include "tag/ReplayGain.hxx"
 #include "ReplayGainInfo.hxx"
 #include "util/ASCII.hxx"
 #include "util/SplitString.hxx"
@@ -52,36 +53,21 @@ vorbis_comment_value(const FLAC__StreamMetadata *block,
 	return comment + name_length + 1;
 }
 
-static bool
-flac_find_float_comment(const FLAC__StreamMetadata *block,
-			const char *cmnt, float *fl)
-{
-	const char *value = vorbis_comment_value(block, cmnt);
-	if (value == nullptr)
-		return false;
-
-	*fl = (float)atof(value);
-	return true;
-}
-
 bool
 flac_parse_replay_gain(ReplayGainInfo &rgi,
 		       const FLAC__StreamMetadata *block)
 {
+	const FLAC__StreamMetadata_VorbisComment &vc =
+		block->data.vorbis_comment;
+
 	rgi.Clear();
 
 	bool found = false;
-	if (flac_find_float_comment(block, "replaygain_album_gain",
+
-				    &rgi.tuples[REPLAY_GAIN_ALBUM].gain))
+	const auto *comments = vc.comments;
-		found = true;
+	for (FLAC__uint32 i = 0, n = vc.num_comments; i < n; ++i)
-	if (flac_find_float_comment(block, "replaygain_album_peak",
+		if (ParseReplayGainVorbis(rgi,
-				    &rgi.tuples[REPLAY_GAIN_ALBUM].peak))
+					  (const char *)comments[i].entry))
-		found = true;
-	if (flac_find_float_comment(block, "replaygain_track_gain",
-				    &rgi.tuples[REPLAY_GAIN_TRACK].gain))
-		found = true;
-	if (flac_find_float_comment(block, "replaygain_track_peak",
-				    &rgi.tuples[REPLAY_GAIN_TRACK].peak))
 			found = true;
 
 	return found;

src/decoder/plugins/VorbisComments.cxx

@@ -24,6 +24,7 @@
 #include "tag/TagHandler.hxx"
 #include "tag/TagBuilder.hxx"
 #include "tag/VorbisComment.hxx"
+#include "tag/ReplayGain.hxx"
 #include "ReplayGainInfo.hxx"
 #include "util/ASCII.hxx"
 #include "util/SplitString.hxx"
@@ -36,27 +37,11 @@ vorbis_comments_to_replay_gain(ReplayGainInfo &rgi, char **comments)
 {
 	rgi.Clear();
 
-	const char *temp;
 	bool found = false;
 
 	while (*comments) {
-		if ((temp =
+		if (ParseReplayGainVorbis(rgi, *comments))
-		     vorbis_comment_value(*comments, "replaygain_track_gain"))) {
-			rgi.tuples[REPLAY_GAIN_TRACK].gain = atof(temp);
 			found = true;
-		} else if ((temp = vorbis_comment_value(*comments,
-							"replaygain_album_gain"))) {
-			rgi.tuples[REPLAY_GAIN_ALBUM].gain = atof(temp);
-			found = true;
-		} else if ((temp = vorbis_comment_value(*comments,
-							"replaygain_track_peak"))) {
-			rgi.tuples[REPLAY_GAIN_TRACK].peak = atof(temp);
-			found = true;
-		} else if ((temp = vorbis_comment_value(*comments,
-							"replaygain_album_peak"))) {
-			rgi.tuples[REPLAY_GAIN_ALBUM].peak = atof(temp);
-			found = true;
-		}
 
 		comments++;
 	}

src/tag/ReplayGain.cxx

@@ -19,6 +19,7 @@
 
 #include "config.h"
 #include "ReplayGain.hxx"
+#include "VorbisComment.hxx"
 #include "ReplayGainInfo.hxx"
 #include "util/ASCII.hxx"
 
@@ -68,3 +69,18 @@ ParseReplayGainTag(ReplayGainInfo &info, const char *name, const char *value)
 
 	return ParseReplayGainTagTemplate(info, NameValue{name, value});
 }
+
+bool
+ParseReplayGainVorbis(ReplayGainInfo &info, const char *entry)
+{
+	struct VorbisCommentEntry {
+		const char *entry;
+
+		gcc_pure
+		const char *operator[](const char *n) const {
+			return vorbis_comment_value(entry, n);
+		}
+	};
+
+	return ParseReplayGainTagTemplate(info, VorbisCommentEntry{entry});
+}

src/tag/ReplayGain.hxx

@@ -27,4 +27,7 @@ struct ReplayGainInfo;
 bool
 ParseReplayGainTag(ReplayGainInfo &info, const char *name, const char *value);
 
+bool
+ParseReplayGainVorbis(ReplayGainInfo &info, const char *entry);
+
 #endif