// mk4io.h --
// $Id: mk4io.h 403187 2005-04-04 20:17:07Z osterfeld $
// This is part of Metakit, the homepage is http://www.equi4.com/metakit/

/** @file
 * Declaration of the file stream and strategy classes.
 */

#ifndef __MK4IO_H__
#define __MK4IO_H__

#include <stdio.h>

/////////////////////////////////////////////////////////////////////////////
/// A file stream can be used to serialize using the stdio library.

class c4_FileStream : public c4_Stream
{
public:
    c4_FileStream (FILE* stream_, bool owned_ =false);
    virtual ~c4_FileStream ();

    virtual int Read(void* buffer_, int length_);
    virtual bool Write(const void* buffer_, int length_);

    FILE* _stream;
    bool _owned;
};

/////////////////////////////////////////////////////////////////////////////
/// A file strategy encapsulates code dealing with all file I/O.

class c4_FileStrategy : public c4_Strategy
{     
public:
        /// Construct a new strategy object
    c4_FileStrategy (FILE* file_ =0);
    virtual ~c4_FileStrategy ();

        /// True if we can do I/O with this object
    virtual bool IsValid() const;
        /// Open a data file by name
    virtual bool DataOpen(const char* fileName_, int mode_);
        /// Read a number of bytes
    virtual int  DataRead(t4_i32 pos_, void* buffer_, int length_);
        /// Write a number of bytes, return true if successful
    virtual void DataWrite(t4_i32 pos_, const void* buffer_, int length_);
        /// Flush and truncate file
    virtual void DataCommit(t4_i32 newSize_);
        /// Support for memory-mapped files
    virtual void ResetFileMapping();
        /// Report total size of the datafile
    virtual t4_i32 FileSize();
        /// Return a good value to use as fresh generation counter
    virtual t4_i32 FreshGeneration();

protected:
        /// Pointer to file object
    FILE* _file;
        /// Pointer to same file object, if it must be deleted at end
    FILE* _cleanup;
};

/////////////////////////////////////////////////////////////////////////////

#endif // __MK4IO_H__
