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common/concatstream.h

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+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * 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 3 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, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#ifndef COMMON_CONCATSTREAM_H
+#define COMMON_CONCATSTREAM_H
+
+#include "common/array.h"
+#include "common/ptr.h"
+#include "common/stream.h"
+
+namespace Common {
+/*
+ * ConcatReadStream provides access to a virtually concatenated stream.
+ *
+ * Manipulating the parent stream directly /will/ mess up a concatstream.
+ *
+ * Assumptions:
+ * - number of streams is small so iterating through array sized by N is cheap
+ * - size of streams doesn't change
+ */
+class ConcatReadStream : public SeekableReadStream {
+private:
+	typedef Common::Array<Common::SharedPtr<Common::SeekableReadStream>> ParentStreamArray;
+	ParentStreamArray _parentStreams;
+	Common::Array<int64> _sizes;
+	Common::Array<int64> _startOffsets;
+
+	uint32 _totalSize, _linearPos;
+	uint32 _volume, _volumePos;
+	bool _err, _eos;
+public:
+	ConcatReadStream(ParentStreamArray parentStreams);
+
+	int64 pos() const override { return _linearPos; }
+	int64 size() const override { return _totalSize; }
+	bool eos() const override { return _eos; }
+	bool err() const override { return _err; }
+	void clearErr() override {
+		_err = false;
+		_eos = false;
+	}
+	bool seek(int64 offset, int whence = SEEK_SET) override;
+	uint32 read(void *dataPtr, uint32 dataSize) override;
+	bool seekToVolume(int volume, int64 offset);
+};
+
+}
+
+#endif // COMMON_CONCATSTREAM_H