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Finite element discretization library
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gzstream.hpp
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1 // ============================================================================
2 // gzstream, C++ iostream classes wrapping the zlib compression library.
3 // Copyright (C) 2001 Deepak Bandyopadhyay, Lutz Kettner
4 //
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18 // ============================================================================
19 //
20 // File : gzstream.h
21 // Revision : $Revision: 1.5 $
22 // Revision_date : $Date: 2002/04/26 23:30:15 $
23 // Author(s) : Deepak Bandyopadhyay, Lutz Kettner
24 //
25 // Standard streambuf implementation following Nicolai Josuttis, "The
26 // Standard C++ Library".
27 // ============================================================================
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532 // 10Oct16: Mark C. Miller:
533 // * Modified to build in MFEM source tree and use 'mfem' namespace
534 // * Modified to use char *mode for constructors/open instead of int
535 // * Changed bufferSize from 47+256 to 8192 (8 kilobytes)
536 // * Other notes:
537 // * consider mode char options for zlib's internal buffer sizes
538 
539 
540 #ifndef MFEM_GZSTREAM_H
541 #define MFEM_GZSTREAM_H
542 
543 #include "../config/config.hpp"
544 
545 // standard C++ with new header file names and std:: namespace
546 #include <iostream>
547 #ifdef MFEM_USE_GZSTREAM
548 #include <zlib.h>
549 #endif
550 
551 namespace mfem
552 {
553 
554 // ----------------------------------------------------------------------------
555 // Internal classes to implement gzstream. See below for user classes.
556 // ----------------------------------------------------------------------------
557 
558 #ifdef MFEM_USE_GZSTREAM
559 class gzstreambuf : public std::streambuf
560 {
561 private:
562  static const int bufferSize = 8192; // size of data buff
563  // totals 512 bytes under g++ for igzstream at the end.
564 
565  gzFile file; // file handle for compressed file
566  char buffer[bufferSize]; // data buffer
567  char opened; // open/close state of stream
568  char mode[16]; // I/O mode chars
569 
570  int flush_buffer();
571 public:
572  gzstreambuf() : opened(0)
573  {
574  setp( buffer, buffer + (bufferSize-1));
575  setg( buffer + 4, // beginning of putback area
576  buffer + 4, // read position
577  buffer + 4); // end position
578  // ASSERT: both input & output capabilities will not be used together
579  }
580  int is_open() { return opened; }
581  gzstreambuf* open(char const *name, char const *mode);
582  gzstreambuf* close();
584 
585  virtual int overflow( int c = traits_type::eof());
586  virtual int underflow();
587  virtual int sync();
588 };
589 
590 class gzstreambase : virtual public std::ios
591 {
592 protected:
594 public:
595  gzstreambase() { init(&buf); }
596  gzstreambase(char const * name, char const *mode);
597  ~gzstreambase();
598  void open(char const * name, char const *mode);
599  void close();
600  gzstreambuf* rdbuf() { return &buf; }
601 };
602 
603 // ----------------------------------------------------------------------------
604 // User classes. Use igzstream and ogzstream analogously to ifstream and
605 // ofstream respectively. They read and write files based on the gz*
606 // function interface of the zlib. Files are compatible with gzip compression.
607 // ----------------------------------------------------------------------------
608 
609 class igzstream : public gzstreambase, public std::istream
610 {
611 public:
612  igzstream() : std::istream( &buf) {}
613  /** Constructs a gzip compressed input stream object and opens
614  the associated file. The mode chars are as in gzopen(),
615  https://refspecs.linuxbase.org/LSB_3.0.0/LSB-PDA/LSB-PDA/zlib-gzopen-1.html.
616  Default mode is "rb". */
617  igzstream(char const * name, char const *mode = "rb")
618  : gzstreambase(name, mode), std::istream( &buf) {}
620  /** Opens a gzip compressed input stream. The mode chars are as in gzopen(),
621  https://refspecs.linuxbase.org/LSB_3.0.0/LSB-PDA/LSB-PDA/zlib-gzopen-1.html.
622  Default mode is "rb". */
623  void open(char const * name, char const *mode = "rb")
624  {
625  gzstreambase::open(name, mode);
626  }
627 };
628 #endif
629 
630 class ifgzstream : public std::istream
631 {
632 public:
633  /** Simple replacement for class @c std::ifstream that automatically detects
634  compressed files in gzip format and transparently uncompresses them.
635  Internally, the classes @c std::filebuf or @ref gzstreambuf are used to
636  handle the file I/O. Reading compressed files requires the MFEM
637  build-time option MFEM_USE_GZSTREAM.
638  @note For uncompressed files, the @a mode option is ignored and the file
639  is opened with @c std::ios_base::in mode.
640  @see @ref ofgzstream,
641  https://refspecs.linuxbase.org/LSB_3.0.0/LSB-PDA/LSB-PDA/zlib-gzopen-1.html. */
642  ifgzstream(char const *name, char const *mode = "rb");
643  ~ifgzstream() { delete buf; }
644 
645 protected:
646  std::streambuf *buf;
647  static bool maybe_gz(const char *fn);
648 };
649 
650 #ifdef MFEM_USE_GZSTREAM
651 class ogzstream : public gzstreambase, public std::ostream
652 {
653 public:
654  ogzstream() : std::ostream( &buf) {}
655  /** Constructs a gzip compressed output stream object and opens
656  the associated file. The mode chars are as in gzopen(),
657  https://refspecs.linuxbase.org/LSB_3.0.0/LSB-PDA/LSB-PDA/zlib-gzopen-1.html.
658  Default mode is "wb6". */
659  ogzstream(char const * name, char const *mode = "wb6")
660  : gzstreambase(name, mode), std::ostream( &buf) {}
662  /** Opens a gzip compressed output stream. The mode chars are as in gzopen(),
663  https://refspecs.linuxbase.org/LSB_3.0.0/LSB-PDA/LSB-PDA/zlib-gzopen-1.html.
664  Default mode is "wb6". */
665  void open(char const * name, char const *mode = "wb6")
666  {
667  gzstreambase::open(name, mode);
668  }
669 };
670 #endif
671 
672 class ofgzstream : public std::ostream
673 {
674 public:
675  static char const *default_mode; // defined in gzstream.cpp
676 
677  /** Simple replacement for class @c std::ofstream that can transparently
678  create files compressed in gzip format (when @a mode contains the
679  character @c 'z') or regular uncompressed files. Internally, the classes
680  @c std::filebuf or @ref gzstreambuf are used to handle the file I/O.
681  The mode chars are as in gzopen() with additional caveat that presence of
682  a @c 'z' character indicates desire to compress. Default mode is "zwb6".
683  Writing compressed files requires the MFEM build-time option
684  MFEM_USE_GZSTREAM.
685  @note For uncompressed files, the @a mode option is ignored and the file
686  is opened with @c std::ios_base::out mode.
687  @see @ref ifgzstream,
688  https://refspecs.linuxbase.org/LSB_3.0.0/LSB-PDA/LSB-PDA/zlib-gzopen-1.html. */
689  ofgzstream(char const *name, char const *mode = default_mode);
690 
691  ~ofgzstream() { delete buf; }
692 
693 protected:
694  std::streambuf *buf;
695 };
696 
697 } // namespace mfem
698 
699 #endif // MFEM_GZSTREAM_H
gzstreambuf buf
Definition: gzstream.hpp:593
gzstreambuf * close()
Definition: gzstream.cpp:62
std::streambuf * buf
Definition: gzstream.hpp:694
virtual int overflow(int c=traits_type::eof())
Definition: gzstream.cpp:123
static bool maybe_gz(const char *fn)
Definition: gzstream.cpp:193
static char const * default_mode
Definition: gzstream.hpp:675
gzstreambuf * rdbuf()
Definition: gzstream.hpp:661
ogzstream(char const *name, char const *mode="wb6")
Definition: gzstream.hpp:659
igzstream(char const *name, char const *mode="rb")
Definition: gzstream.hpp:617
ifgzstream(char const *name, char const *mode="rb")
Definition: gzstream.cpp:202
gzstreambuf * rdbuf()
Definition: gzstream.hpp:600
ofgzstream(char const *name, char const *mode=default_mode)
Definition: gzstream.cpp:240
void open(char const *name, char const *mode="wb6")
Definition: gzstream.hpp:665
gzstreambuf * rdbuf()
Definition: gzstream.hpp:619
std::streambuf * buf
Definition: gzstream.hpp:646
void open(char const *name, char const *mode="rb")
Definition: gzstream.hpp:623
virtual int underflow()
Definition: gzstream.cpp:76
virtual int sync()
Definition: gzstream.cpp:142
gzstreambuf * open(char const *name, char const *mode)
Definition: gzstream.cpp:46
void open(char const *name, char const *mode)
Definition: gzstream.cpp:172