gzstream.hpp

// ============================================================================
// 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      : $Revision$
// Revision_date : $Date$
// Author(s)     : Deepak Bandyopadhyay, Lutz Kettner
//
// Standard streambuf implementation following Nicolai Josuttis, "The
// Standard C++ Library".
// ============================================================================
 
#ifndef IO_GZSTREAM_HPP
#define IO_GZSTREAM_HPP
 
// standard C++ with new header file names and std:: namespace
#include <zlib.h>
 
#include <fstream>
#include <iostream>
 
namespace OpenMD {
 
  // ----------------------------------------------------------------------------
  // 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);
    }
  };
}  // namespace OpenMD
 
#endif