vcmi/lib/Filesystem/CMemoryStream.h

/*
 * CMemoryStream.h, part of VCMI engine
 *
 * Authors: listed in file AUTHORS in main folder
 *
 * License: GNU General Public License v2.0 or later
 * Full text of license available in license.txt file, in main folder
 *
 */

#pragma once

#include "CInputStream.h"

/**
 * A class which provides method definitions for reading from memory.
 */
class DLL_LINKAGE CMemoryStream : public CInputStream
{
public:
	/**
	 * Default c-tor.
	 */
	CMemoryStream();

	/**
	 * C-tor. The data buffer will be freed by the stream's destructor.
	 *
	 * @param data A pointer to the data array.
	 * @param size The size in bytes of the array.
	 * @param freeData Flag which specifies if the data array should be freed in the memory stream's destructor.
	 */
	CMemoryStream(const ui8 * data, si64 size, bool freeData = false);

	/**
	 * D-tor. Frees the data array if the freeData flag was set to true.
	 */
	~CMemoryStream();

	/**
	 * Opens the stream with the given data array. If a stream is currently loaded, it will be freed
	 * if neccessary.
	 *
	 * @param data A pointer to the data array.
	 * @param size The size in bytes of the array.
	 * @param freeData Flag which specifies if the data array should be freed in the memory stream's destructor.
	 */
	void open(const ui8 * data, si64 size, bool freeData = false);

	/**
	 * Reads n bytes from the stream into the data buffer.
	 *
	 * @param data A pointer to the destination data array.
	 * @param size The number of bytes to read.
	 * @return the number of bytes read actually.
	 */
	si64 read(ui8 * data, si64 size);

	/**
	 * Seeks the internal read pointer to the specified position.
	 *
	 * @param position The read position from the beginning.
	 * @return the position actually moved to, -1 on error.
	 */
	si64 seek(si64 position);

	/**
	 * Gets the current read position in the stream.
	 *
	 * @return the read position.
	 */
	si64 tell();

	/**
	 * Skips delta numbers of bytes.
	 *
	 * @param delta The count of bytes to skip.
	 * @return the count of bytes skipped actually.
	 */
	si64 skip(si64 delta);

	/**
	 * Gets the length in bytes of the stream.
	 *
	 * @return the length in bytes of the stream.
	 */
	si64 getSize();

	/**
	 * Closes the stream and releases any system resources associated with the stream explicitely.
	 */
	void close();

private:
	/** A pointer to the data array. */
	const ui8 * data;

	/** The size in bytes of the array. */
	si64 size;

	/** Current reading position of the stream. */
	si64 position;

	/** Flag which specifies if the data array should be freed in the memory stream's destructor. */
	bool freeData;
};