gzstream.h

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// ============================================================================
// gzstream, C++ iostream classes wrapping the zlib compression library.
// Copyright (C) 2001  Deepak Bandyopadhyay, Lutz Kettner
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library 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
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
// ============================================================================
//
// File          : gzstream.h
// Revision      : $Revision: 1.5 $
// Revision_date : $Date: 2002/04/26 23:30:15 $
// Author(s)     : Deepak Bandyopadhyay, Lutz Kettner
//
// Standard streambuf implementation following Nicolai Josuttis, "The
// Standard C++ Library".
// ============================================================================
 
#ifndef GZSTREAM_H
#define GZSTREAM_H 1
 
// standard C++ with new header file names and std:: namespace
#include <iostream>
#include <fstream>
#include <zlib.h>
 
#ifdef GZSTREAM_NAMESPACE
namespace GZSTREAM_NAMESPACE {
#endif
 
// ----------------------------------------------------------------------------
// Internal classes to implement gzstream. See below for user classes.
// ----------------------------------------------------------------------------
 
class gzstreambuf : public std::streambuf {
private:
    static const int bufferSize = 47+256;    // size of data buff
    // totals 512 bytes under g++ for igzstream at the end.
 
    gzFile           file;               // file handle for compressed file
    char             buffer[bufferSize]; // data buffer
    char             opened;             // open/close state of stream
    int              mode;               // I/O mode
 
    int flush_buffer();
public:
    gzstreambuf() : opened(0) {
        setp(buffer, buffer + (bufferSize-1));
        setg(buffer + 4,      // beginning of putback area
             buffer + 4,     // read position
             buffer + 4);    // end position
        // ASSERT: both input & output capabilities will not be used together
    }
    int is_open() {
        return opened;
    }
    gzstreambuf *open(const char *name, int open_mode);
    gzstreambuf *close();
    ~gzstreambuf() {
        close();
    }
 
    virtual int     overflow(int c = EOF);
    virtual int     underflow();
    virtual int     sync();
};
 
class gzstreambase : virtual public std::ios {
protected:
    gzstreambuf buf;
public:
    gzstreambase() {
        init(&buf);
    }
    gzstreambase(const char *name, int open_mode);
    ~gzstreambase();
    void open(const char *name, int open_mode);
    void close();
    gzstreambuf *rdbuf() {
        return &buf;
    }
};
 
// ----------------------------------------------------------------------------
// User classes. Use igzstream and ogzstream analogously to ifstream and
// ofstream respectively. They read and write files based on the gz*
// function interface of the zlib. Files are compatible with gzip compression.
// ----------------------------------------------------------------------------
 
class igzstream : public gzstreambase, public std::istream {
public:
    igzstream() : std::istream(&buf) {}
    igzstream(const char *name, int open_mode = std::ios::in)
        : gzstreambase(name, open_mode), std::istream(&buf) {}
    gzstreambuf *rdbuf() {
        return gzstreambase::rdbuf();
    }
    void open(const char *name, int open_mode = std::ios::in) {
        gzstreambase::open(name, open_mode);
    }
};
 
class ogzstream : public gzstreambase, public std::ostream {
public:
    ogzstream() : std::ostream(&buf) {}
    ogzstream(const char *name, int mode = std::ios::out)
        : gzstreambase(name, mode), std::ostream(&buf) {}
    gzstreambuf *rdbuf() {
        return gzstreambase::rdbuf();
    }
    void open(const char *name, int open_mode = std::ios::out) {
        gzstreambase::open(name, open_mode);
    }
};
 
#ifdef GZSTREAM_NAMESPACE
} // namespace GZSTREAM_NAMESPACE
#endif
 
#endif // GZSTREAM_H
// ============================================================================
// EOF //