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// stdiostream.hpp
//
// Copyright (c) 2010 Michael Thomas Greer
// Distributed under the Boost Software License, Version 1.0
// (See <a href="http://www.boost.org/LICENSE_1_0.txt">http://www.boost.org/LICENSE_1_0.txt</a> )
//
#pragma once
#ifndef DUTHOMHAS_STDIOSTREAM_HPP
#define DUTHOMHAS_STDIOSTREAM_HPP
#include <cstdio>
#include <iostream>
#include <streambuf>
#include <string>
#include <vector>
namespace duthomhas
{
/* /////////////////////////////////////////////////////////////////////////
basic_stdiobuf
///////////////////////////////////////////////////////////////////////// */
template <
typename CharType,
typename CharTraits = std::char_traits <CharType>
>
class basic_stdiobuf: public std::basic_streambuf <CharType, CharTraits>
{
//------------------------------------------------------------------------
public:
//------------------------------------------------------------------------
typedef CharType char_type;
typedef CharTraits traits_type;
typedef typename traits_type::int_type int_type;
typedef typename traits_type::pos_type pos_type;
typedef typename traits_type::off_type off_type;
typedef basic_stdiobuf <char_type, traits_type> this_type;
//......................................................................
basic_stdiobuf( FILE* fp = NULL ):
fp( fp )
{ }
//......................................................................
//BUG 1: Hey! I never get called! (How is that?)
~basic_stdiobuf()
{
this->close();
}
//......................................................................
bool is_open() const throw()
{
return fp != NULL;
}
//......................................................................
this_type* open( const char* filename, std::ios_base::openmode mode )
{
if (is_open()) return NULL;
// Figure out the open mode flags . . . . . . . . . . . . . . . . . .
std::string fmode;
bool is_ate = mode & std::ios_base::ate;
bool is_bin = mode & std::ios_base::binary;
mode &= ~(std::ios_base::ate | std::ios_base::binary);
#define _(flag) std::ios_base::flag
if (mode == ( _(in) )) fmode = "r";
else if (mode == ( _(out) & _(trunc))) fmode = "w";
else if (mode == (_(app) & _(out) )) fmode = "a";
else if (mode == ( _(in) & _(out) )) fmode = "r+";
else if (mode == ( _(in) & _(out) & _(trunc))) fmode = "w+";
else if (mode == (_(app) & _(in) & _(out) )) fmode = "a+";
// I would prefer to throw an exception here,
// but the standard only wants a NULL result.
else return NULL;
#undef _
if (is_bin) fmode.insert( 1, 1, 'b' );
// Try opening the file . . . . . . . . . . . . . . . . . . . . . . .
fp = std::fopen( filename, fmode.c_str() );
if (!fp) return NULL;
// Reposition to EOF if wanted . . . . . . . . . . . . . . . . . . . .
if (is_ate) std::fseek( fp, 0, SEEK_END );
return this;
}
//......................................................................
this_type* close()
{
if (fp)
{
std::fclose( fp );
fp = NULL;
}
pushbacks.clear();
return this;
}
//......................................................................
FILE* stdiofile() const
{
return fp;
}
//------------------------------------------------------------------------
protected:
//------------------------------------------------------------------------
//......................................................................
// Get the CURRENT character without advancing the file pointer
virtual int_type underflow()
{
// Return anything previously pushed-back
if (pushbacks.size())
return pushbacks.back();
// Else do the right thing
fpos_t pos;
if (std::fgetpos( fp, &pos ) != 0)
return traits_type::eof();
int c = std::fgetc( fp );
std::fsetpos( fp, &pos );
return maybe_eof( c );
}
//......................................................................
// Get the CURRENT character AND advance the file pointer
virtual int_type uflow()
{
// Return anything previously pushed-back
if (pushbacks.size())
{
int_type c = pushbacks.back();
pushbacks.pop_back();
return c;
}
// Else do the right thing
return maybe_eof( std::fgetc( fp ) );
}
//......................................................................
virtual int_type pbackfail( int_type c = traits_type::eof() )
{
if (!is_open())
return traits_type::eof();
// If the argument c is EOF and the file pointer is not at the
// beginning of the character sequence, it is decremented by one.
if (traits_type::eq_int_type( c, traits_type::eof() ))
{
pushbacks.clear();
return std::fseek( fp, -1L, SEEK_CUR )
? traits_type::eof()
: 0;
}
// Otherwise, make the argument the next value to be returned by
// underflow() or uflow()
pushbacks.push_back( c );
return c;
}
virtual int_type overflow( int_type c = traits_type::eof() )
{
pushbacks.clear();
// Do nothing
if (traits_type::eq_int_type( c, traits_type::eof() ))
return 0;
// Else write a character
return maybe_eof( std::fputc( c, fp ) );
}
//......................................................................
virtual this_type* setbuf( char* s, std::streamsize n )
{
return std::setvbuf( fp, s, (s and n) ? _IOLBF : _IONBF, (size_t)n )
? NULL
: this;
}
//......................................................................
virtual pos_type seekoff(
off_type offset,
std::ios_base::seekdir direction,
std::ios_base::openmode which = std::ios_base::in | std::ios_base::out
) {
pushbacks.clear();
return std::fseek( fp, offset,
(direction == std::ios_base::beg) ? SEEK_SET :
(direction == std::ios_base::cur) ? SEEK_CUR :
SEEK_END
) ? (-1) : std::ftell( fp );
}
//......................................................................
virtual pos_type seekpos(
pos_type position,
std::ios_base::openmode which = std::ios_base::in | std::ios_base::out
) {
pushbacks.clear();
return std::fseek( fp, position, SEEK_SET )
? (-1)
: std::ftell( fp );
}
//......................................................................
virtual int sync()
{
pushbacks.clear();
return std::fflush( fp )
? traits_type::eof()
: 0;
}
//------------------------------------------------------------------------
private:
//------------------------------------------------------------------------
FILE* fp;
std::vector <int_type> pushbacks; // we'll treat this like a stack
//......................................................................
// Utility function to make sure EOF gets translated to the proper value
inline int_type maybe_eof( int value ) const
{
return (value == EOF) ? traits_type::eof() : value;
}
};
/* /////////////////////////////////////////////////////////////////////////
basic_stdiostream
///////////////////////////////////////////////////////////////////////// */
template <
typename CharType,
typename CharTraits = std::char_traits <CharType>
>
struct basic_stdiostream: public std::basic_iostream <CharType, CharTraits>
{
typedef CharType char_type;
typedef CharTraits traits_type;
typedef basic_stdiobuf <char_type, traits_type> sbuf_type;
typedef basic_stdiostream <char_type, traits_type> this_type;
typedef std::basic_iostream <char_type, traits_type> base_type;
//......................................................................
basic_stdiostream( FILE* fp = NULL ):
base_type( new sbuf_type( fp ) )
{ }
//......................................................................
basic_stdiostream( const char* filename, std::ios_base::openmode mode ):
//BUG 2: Oops! This is a potential memory leak!
base_type( (new sbuf_type)->open( filename, mode ) )
{ }
//......................................................................
void open(
const char* filename,
std::ios_base::openmode mode = std::ios_base::in | std::ios_base::out
) {
sbuf_type* buf = static_cast <sbuf_type*> ( this->rdbuf() );
if (!(buf->open( filename, mode )))
this->setstate( std::ios_base::badbit );
}
//......................................................................
void close()
{
sbuf_type* buf = static_cast <sbuf_type*> ( this->rdbuf() );
buf->close();
}
};
/* /////////////////////////////////////////////////////////////////////////
Useful typedefs
///////////////////////////////////////////////////////////////////////// */
typedef basic_stdiobuf <char> stdiobuf;
typedef basic_stdiostream <char> stdiostream;
} // namespace duthomhas
#endif
// end stdiostream.hpp
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