gzstreambuf.h

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00001 /** @file rutz/gzstreambuf.h handle gzip-encoding through a c++
00002     iostreams interface */
00003 
00004 ///////////////////////////////////////////////////////////////////////
00005 //
00006 // Copyright (c) 2001-2004 California Institute of Technology
00007 // Copyright (c) 2004-2007 University of Southern California
00008 // Rob Peters <rjpeters at usc dot edu>
00009 //
00010 // created: Wed Jun 20 09:12:51 2001
00011 // commit: $Id: gzstreambuf.h 8249 2007-04-12 06:03:40Z rjpeters $
00012 // $HeadURL: svn://isvn.usc.edu/software/invt/trunk/saliency/src/rutz/gzstreambuf.h $
00013 //
00014 // --------------------------------------------------------------------
00015 //
00016 // This file is part of GroovX.
00017 //   [http://ilab.usc.edu/rjpeters/groovx/]
00018 //
00019 // GroovX is free software; you can redistribute it and/or modify it
00020 // under the terms of the GNU General Public License as published by
00021 // the Free Software Foundation; either version 2 of the License, or
00022 // (at your option) any later version.
00023 //
00024 // GroovX is distributed in the hope that it will be useful, but
00025 // WITHOUT ANY WARRANTY; without even the implied warranty of
00026 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00027 // General Public License for more details.
00028 //
00029 // You should have received a copy of the GNU General Public License
00030 // along with GroovX; if not, write to the Free Software Foundation,
00031 // Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
00032 //
00033 ///////////////////////////////////////////////////////////////////////
00034 
00035 #ifndef GROOVX_RUTZ_GZSTREAMBUF_H_UTC20050626084020_DEFINED
00036 #define GROOVX_RUTZ_GZSTREAMBUF_H_UTC20050626084020_DEFINED
00037 
00038 #include <istream>
00039 #include <ostream>
00040 #include <streambuf>
00041 #include <zlib.h>
00042 
00043 namespace rutz
00044 {
00045   class fstring;
00046 
00047   template <class T> class shared_ptr;
00048 
00049   /// A std::streambuf implementation that handles gzip-encoded data.
00050   class gzstreambuf : public std::streambuf
00051   {
00052   private:
00053     bool m_opened;
00054     int m_mode;
00055     gzFile m_gzfile;
00056 
00057     gzstreambuf(const gzstreambuf&);
00058     gzstreambuf& operator=(const gzstreambuf&);
00059 
00060     static const int s_buf_size = 4092;
00061     static const int s_pback_size = 4;
00062     char m_buf[s_buf_size];
00063 
00064     int flushoutput();
00065 
00066   public:
00067     gzstreambuf(const char* name, int om, bool throw_exception=false);
00068     ~gzstreambuf() { close(); }
00069 
00070     bool is_open() { return m_opened; }
00071 
00072     void ensure_open();
00073 
00074     void close();
00075 
00076     virtual int underflow();
00077 
00078     virtual int overflow(int c);
00079 
00080     virtual int sync();
00081   };
00082 
00083   /** Opens a file for writing. An exception will be thrown if the
00084       specified file cannot be opened. The output file will be
00085       gz-compressed if the filename ends with ".gz". */
00086   shared_ptr<std::ostream> ogzopen(const rutz::fstring& filename,
00087                                    std::ios::openmode flags =
00088                                    std::ios::openmode(0));
00089 
00090   /// Overload.
00091   shared_ptr<std::ostream> ogzopen(const char* filename,
00092                                    std::ios::openmode flags =
00093                                    std::ios::openmode(0));
00094 
00095   /** Opens a file for reading. An exception will be thrown if the
00096       specified file cannot be opened. If the file is gz-compressed,
00097       this will be automagically detected regardless of the filename
00098       extension. */
00099   shared_ptr<std::istream> igzopen(const rutz::fstring& filename,
00100                                    std::ios::openmode flags =
00101                                    std::ios::openmode(0));
00102 
00103   /// Overload.
00104   shared_ptr<std::istream> igzopen(const char* filename,
00105                                    std::ios::openmode flags =
00106                                    std::ios::openmode(0));
00107 }
00108 
00109 static const char __attribute__((used)) vcid_groovx_rutz_gzstreambuf_h_utc20050626084020[] = "$Id: gzstreambuf.h 8249 2007-04-12 06:03:40Z rjpeters $ $HeadURL: svn://isvn.usc.edu/software/invt/trunk/saliency/src/rutz/gzstreambuf.h $";
00110 #endif // !GROOVX_RUTZ_GZSTREAMBUF_H_UTC20050626084020_DEFINED
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