UT/UT_FPStream.h

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/*
 * PROPRIETARY INFORMATION.  This software is proprietary to
 * Side Effects Software Inc., and is not to be reproduced,
 * transmitted, or disclosed in any way without written permission.
 *
 * Produced by:
 *      Side Effects Software Inc
 *      477 Richmond Street West
 *      Toronto, Ontario
 *      Canada   M5V 3E7
 *      416-504-9876
 *
 * NAME:        UT_FPStream.h ( UT Library, C++)
 *
 * COMMENTS:    Stream using FILE * objects instead of file descriptors
 *
 *      In general, use this class instead of UT_FDStream if possible.  This is
 *      because this class is buffered while the FDStreams are not (and thus
 *      have very poor performance).
 */

#ifndef __UT_FPStream__
#define __UT_FPStream__

#include "UT_API.h"

#include <istream>
#include <ostream>
#include <streambuf>
#include <stdio.h>
#include <string.h>
#include "UT_Assert.h"

#ifdef GCC3
using namespace std;
#endif

/************************************************************
 * UT_OFPStream
 * - a stream that writes on a file descriptor
 ************************************************************/

class UT_API UT_FPOutBuf : public std::streambuf {
public:
    UT_FPOutBuf (FILE *_fp)
           : myFP(_fp)
    {
    }
    void close()
    {
        UT_ASSERT(myFP);
        ::fclose(myFP);
        myFP = 0;
    }

protected:
    // write one character
    virtual int_type    overflow(int_type c) 
                        {
                            UT_ASSERT(myFP);
                            return putc(c, myFP);
                        }

    // In order to allow tellg to work, we need to provide seekoff.
    virtual pos_type    seekoff(off_type _Off,
                            ios_base::seekdir _Way,
                            ios_base::openmode /*_Mode*/ = ios::out)
                        {
                            // We only support seeking to the current position,
                            // ie: telling.
                            UT_ASSERT(myFP);
                            UT_ASSERT(_Off == 0);
                            UT_ASSERT(_Way == ios_base::cur);
                            return (pos_type)ftell(myFP);
                        }

    // write multiple characters
    virtual std::streamsize     xsputn (const char* s, std::streamsize num) 
                        {
                            UT_ASSERT(myFP);
                            return fwrite(s, 1, num, myFP);
                        }

protected:
    FILE        *myFP;          // My file pointer
};

class UT_API UT_OFPStream : public std::ostream {
  protected:
    UT_FPOutBuf buf;
  public:
    UT_OFPStream (FILE *fp) : std::ostream(0), buf(fp) 
    {
        rdbuf(&buf);
    }
    void close()                { buf.close(); }
};

#endif

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