encoder/vorbis: add wrapper class for vorbis_comment

Makefile.am

@@ -585,6 +585,7 @@ if HAVE_XIPH
 noinst_LIBRARIES += libxiph.a
 
 libxiph_a_SOURCES = \
+	src/lib/xiph/VorbisComment.hxx \
 	src/lib/xiph/VorbisComments.cxx src/lib/xiph/VorbisComments.hxx \
 	src/lib/xiph/XiphTags.cxx src/lib/xiph/XiphTags.hxx
 libxiph_a_CPPFLAGS = $(AM_CPPFLAGS) \

src/encoder/plugins/VorbisEncoderPlugin.cxx

@@ -20,6 +20,7 @@
 #include "config.h"
 #include "VorbisEncoderPlugin.hxx"
 #include "OggEncoder.hxx"
+#include "lib/xiph/VorbisComment.hxx"
 #include "AudioFormat.hxx"
 #include "config/ConfigError.hxx"
 #include "util/StringUtil.hxx"
@@ -202,11 +203,8 @@ VorbisEncoder::HeaderOut(vorbis_comment &vc)
 void
 VorbisEncoder::SendHeader()
 {
-	vorbis_comment vc;
-
-	vorbis_comment_init(&vc);
+	VorbisComment vc;
 	HeaderOut(vc);
-	vorbis_comment_clear(&vc);
 }
 
 Encoder *
@@ -260,24 +258,22 @@ VorbisEncoder::PreTag(gcc_unused Error &error)
 }
 
 static void
-copy_tag_to_vorbis_comment(vorbis_comment *vc, const Tag &tag)
+copy_tag_to_vorbis_comment(VorbisComment &vc, const Tag &tag)
 {
 	for (const auto &item : tag) {
 		char name[64];
 		ToUpperASCII(name, tag_item_names[item.type], sizeof(name));
-		vorbis_comment_add_tag(vc, name, item.value);
+		vc.AddTag(name, item.value);
 	}
 }
 
 bool
 VorbisEncoder::SendTag(const Tag &tag, gcc_unused Error &error)
 {
-	vorbis_comment comment;
-
 	/* write the vorbis_comment object */
 
-	vorbis_comment_init(&comment);
-	copy_tag_to_vorbis_comment(&comment, tag);
+	VorbisComment comment;
+	copy_tag_to_vorbis_comment(comment, tag);
 
 	/* reset ogg_stream_state and begin a new stream */
 
@@ -286,7 +282,6 @@ VorbisEncoder::SendTag(const Tag &tag, gcc_unused Error &error)
 	/* send that vorbis_comment to the ogg_stream_state */
 
 	HeaderOut(comment);
-	vorbis_comment_clear(&comment);
 
 	return true;
 }

src/lib/xiph/VorbisComment.hxx

+/*
+ * Copyright 2003-2016 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_VORBIS_COMMENT_HXX
+#define MPD_VORBIS_COMMENT_HXX
+
+#include "check.h"
+
+#include <vorbis/codec.h>
+
+/**
+ * OO wrapper for a #vorbis_comment instance.
+ */
+class VorbisComment {
+	vorbis_comment vc;
+
+public:
+	VorbisComment() {
+		vorbis_comment_init(&vc);
+	}
+
+	~VorbisComment() {
+		vorbis_comment_clear(&vc);
+	}
+
+	VorbisComment(const VorbisComment &) = delete;
+	VorbisComment &operator=(const VorbisComment &) = delete;
+
+	operator vorbis_comment &() {
+		return vc;
+	}
+
+	operator vorbis_comment *() {
+		return &vc;
+	}
+
+	void AddTag(const char *tag, const char *contents) {
+		vorbis_comment_add_tag(&vc, tag, contents);
+	}
+};
+
+#endif