1 stdio_streambuf

     1 /*

     2  * Copyright (c) 1999

     3  * Silicon Graphics Computer Systems, Inc.

     4  *

     5  * Copyright (c) 1999 

     6  * Boris Fomitchev

     7  *

     8  * This material is provided "as is", with absolutely no warranty expressed

     9  * or implied. Any use is at your own risk.

    10  *

    11  * Permission to use or copy this software for any purpose is hereby granted 

    12  * without fee, provided the above notices are retained on all copies.

    13  * Permission to modify the code and to distribute modified code is granted,

    14  * provided the above notices are retained, and a notice that the code was

    15  * modified is included with the above copyright notice.

    16  *

    17  */ 

    18 // This header is an extension.  It defines two streambufs:

    19 // stdio_istreambuf, a read-only streambuf synchronized with a C stdio

    20 // FILE object, and stdio_ostreambuf, a write-only streambuf

    21 // synchronized with a C stdio FILE object.  Note that neither 

    22 // stdio_istreambuf nor stdio_ostreambuf is a template; both classes

    23 // are derived from basic_streambuf<char, char_traits<char> >.

    24 

    25 // Note: the imbue() member function is a no-op.  In particular, these

    26 // classes assume that codecvt<char, char, mbstate_t> is always an identity

    27 // transformation.  This is true of the default locale, and of all locales

    28 // defined for the C I/O library.  If you need to use a locale where 

    29 // the codecvt<char, char, mbstate_t> facet performs a nontrivial 

    30 // conversion, then you should use basic_filebuf<> instead of stdio_istreambuf

    31 // or stdio_ostreambuf.  (If you don't understand what any of this means, 

    32 // then it's not a feature you need to worry about.  Locales where 

    33 // codecvt<char, char, mbstate_t> does something nontrivial are a rare

    34 // corner case.)

    35 

    36 

    37 #ifndef _STLP_STDIO_STREAMBUF

    38 #define _STLP_STDIO_STREAMBUF

    39 

    40 #if !defined(STLP_WINCE)

    41 

    42 #include <streambuf>            // For basic_streambuf<>

    43 #include <cstdio>              // For FILE.

    44 

    45 # ifndef _STLP_HAS_NO_NAMESPACES

    46 // This is an extension.  It is in namespace SGI, not namespace std

    47 namespace _SgI {

    48 

    49 # ifdef _STLP_USE_NAMESPACES

    50 using namespace _STLP_STD;

    51   // MSVC needs this

    52 using _STLP_STD::streamsize;

    53 using _STLP_STD::streambuf;

    54 using _STLP_STD::basic_streambuf;

    55 using _STLP_STD::ios_base;

    56   // using _STLP_STD::ios_base::openmode;

    57 # endif

    58 # endif

    59 

    60 // Base class for features common to stdio_istreambuf and stdio_ostreambuf

    61 class stdio_streambuf_base : public basic_streambuf<char, _STLP_STD::char_traits<char> >

    62 {

    63 public:                         // Constructor, destructor.

    64   // The argument may not be null.  It must be an open file pointer.

    65   stdio_streambuf_base(FILE*);

    66 

    67   // The destructor flushes the stream, but does not close it.

    68   ~stdio_streambuf_base();

    69 

    70 protected:                      // Virtual functions from basic_streambuf.

    71   streambuf* setbuf(char*, streamsize);

    72 

    73   pos_type seekoff(off_type, ios_base::seekdir,

    74                    ios_base::openmode

    75                           = ios_base::in | ios_base::out);

    76   pos_type seekpos(pos_type,

    77                    ios_base::openmode

    78                           = ios_base::in | ios_base::out);

    79   int sync();

    80 

    81 protected:

    82   FILE* _M_file;

    83 };

    84 

    85 class stdio_istreambuf : public stdio_streambuf_base

    86 {

    87 public:                         // Constructor, destructor.

    88   stdio_istreambuf(FILE* __f) : stdio_streambuf_base(__f) {}

    89 

    90   ~stdio_istreambuf();

    91 

    92 protected:                      // Virtual functions from basic_streambuf.

    93   streamsize showmanyc();

    94   int_type underflow();

    95   int_type uflow();

    96   virtual int_type pbackfail(int_type c = traits_type::eof());

    97 };

    98 

    99 class stdio_ostreambuf : public stdio_streambuf_base

   100 {

   101 public:                         // Constructor, destructor.

   102   stdio_ostreambuf(FILE* __f) : stdio_streambuf_base(__f) {}

   103   ~stdio_ostreambuf();

   104 

   105 protected:                      // Virtual functions from basic_streambuf.

   106   streamsize showmanyc();

   107   int_type overflow(int_type c = traits_type::eof());

   108 };

   109 

   110 # ifndef _STLP_HAS_NO_NAMESPACES

   111 } // Close namespace _SgI.

   112 # endif

   113 

   114 #endif /* _STLP_STDIO_STREAMBUF */

   115 

   116 #endif /* _STLP_WINCE */

   117 

   118 // Local Variables:

   119 // mode:C++

   120 // End:

   121