decoder/flac: add class FlacStreamDecoder wrapping a FLAC__StreamDecoder*

Makefile.am

@@ -1052,6 +1052,7 @@ libdecoder_a_SOURCES += \
 	src/decoder/plugins/FlacPcm.cxx src/decoder/plugins/FlacPcm.hxx \
 	src/decoder/plugins/FlacDomain.cxx src/decoder/plugins/FlacDomain.hxx \
 	src/decoder/plugins/FlacCommon.cxx src/decoder/plugins/FlacCommon.hxx \
+	src/decoder/plugins/FlacStreamDecoder.hxx \
 	src/decoder/plugins/FlacDecoderPlugin.cxx \
 	src/decoder/plugins/FlacDecoderPlugin.h
 endif

src/decoder/plugins/FlacDecoderPlugin.cxx

@@ -19,6 +19,7 @@
 
 #include "config.h" /* must be first for large file support */
 #include "FlacDecoderPlugin.h"
+#include "FlacStreamDecoder.hxx"
 #include "FlacDomain.hxx"
 #include "FlacCommon.hxx"
 #include "FlacMetadata.hxx"
@@ -115,17 +116,17 @@ flac_scan_stream(InputStream &is,
 /**
  * Some glue code around FLAC__stream_decoder_new().
  */
-static FLAC__StreamDecoder *
+static FlacStreamDecoder
 flac_decoder_new(void)
 {
-	FLAC__StreamDecoder *sd = FLAC__stream_decoder_new();
-	if (sd == nullptr) {
+	FlacStreamDecoder sd;
+	if (!sd) {
 		LogError(flac_domain,
 			 "FLAC__stream_decoder_new() failed");
-		return nullptr;
+		return sd;
 	}
 
-	if(!FLAC__stream_decoder_set_metadata_respond(sd, FLAC__METADATA_TYPE_VORBIS_COMMENT))
+	if(!FLAC__stream_decoder_set_metadata_respond(sd.get(), FLAC__METADATA_TYPE_VORBIS_COMMENT))
 		LogDebug(flac_domain,
 			 "FLAC__stream_decoder_set_metadata_respond() has failed");
 
@@ -286,17 +287,13 @@ flac_decode_internal(Decoder &decoder,
 		     InputStream &input_stream,
 		     bool is_ogg)
 {
-	FLAC__StreamDecoder *flac_dec;
-
-	flac_dec = flac_decoder_new();
-	if (flac_dec == nullptr)
+	auto flac_dec = flac_decoder_new();
+	if (!flac_dec)
 		return;
 
 	FlacDecoder data(decoder, input_stream);
 
-	FlacInitAndDecode(data, flac_dec, is_ogg);
-
-	FLAC__stream_decoder_delete(flac_dec);
+	FlacInitAndDecode(data, flac_dec.get(), is_ogg);
 }
 
 static void

src/decoder/plugins/FlacStreamDecoder.hxx

@@ -0,0 +1,67 @@
+/*
+ * 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_FLAC_STREAM_DECODER
+#define MPD_FLAC_STREAM_DECODER
+
+#include "check.h"
+
+#include <FLAC/stream_decoder.h>
+
+#include <utility>
+
+#include <assert.h>
+
+/**
+ * OO wrapper for a FLAC__StreamDecoder.
+ */
+class FlacStreamDecoder {
+	FLAC__StreamDecoder *decoder;
+
+public:
+	FlacStreamDecoder()
+		:decoder(FLAC__stream_decoder_new()) {}
+
+	FlacStreamDecoder(FlacStreamDecoder &&src)
+		:decoder(src.decoder) {
+		src.decoder = nullptr;
+	}
+
+	~FlacStreamDecoder() {
+		if (decoder != nullptr)
+			FLAC__stream_decoder_delete(decoder);
+	}
+
+	FlacStreamDecoder &operator=(FlacStreamDecoder &&src) {
+		std::swap(decoder, src.decoder);
+		return *this;
+	}
+
+	operator bool() const {
+		return decoder != nullptr;
+	}
+
+	FLAC__StreamDecoder *get() {
+		assert(decoder != nullptr);
+
+		return decoder;
+	}
+};
+
+#endif