input/rewind: move code to class ProxyInputStream

src/input/ProxyInputStream.hxx

@@ -0,0 +1,64 @@
+/*
+ * Copyright (C) 2003-2014 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_PROXY_INPUT_STREAM_HXX
+#define MPD_PROXY_INPUT_STREAM_HXX
+
+#include "InputStream.hxx"
+
+struct Tag;
+
+/**
+ * An #InputStream that forwards all methods call to another
+ * #InputStream instance.  This can be used as a base class to
+ * override selected methods.
+ */
+class ProxyInputStream : public InputStream {
+protected:
+	InputStream &input;
+
+public:
+	gcc_nonnull_all
+	ProxyInputStream(InputStream *_input);
+
+	virtual ~ProxyInputStream();
+
+	ProxyInputStream(const ProxyInputStream &) = delete;
+	ProxyInputStream &operator=(const ProxyInputStream &) = delete;
+
+	/* virtual methods from InputStream */
+	bool Check(Error &error) override;
+	void Update() override;
+	bool Seek(offset_type new_offset, int whence, Error &error) override;
+	bool IsEOF() override;
+	Tag *ReadTag() override;
+	bool IsAvailable() override;
+	size_t Read(void *ptr, size_t read_size, Error &error) override;
+
+protected:
+	/**
+	 * Copy public attributes from the underlying input stream to the
+	 * "rewind" input stream.  This function is called when a method of
+	 * the underlying stream has returned, which may have modified these
+	 * attributes.
+	 */
+	void CopyAttributes();
+};
+
+#endif