topical media & game development
lib-of-vs-libs-Poco-include-Poco-UnbufferedStreamBuf.h / h
//
// UnufferedStreamBuf.h
//
//
//
// Library: Foundation
// Package: Streams
// Module: StreamBuf
//
// Definition of template BasicUnbufferedStreamBuf and class UnbufferedStreamBuf.
//
// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// Permission is hereby granted, free of charge, to any person or organization
// obtaining a copy of the software and accompanying documentation covered by
// this license (the "Software") to use, reproduce, display, distribute,
// execute, and transmit the Software, and to prepare derivative works of the
// Software, and to permit third-parties to whom the Software is furnished to
// do so, all subject to the following:
//
// The copyright notices in the Software and this entire statement, including
// the above license grant, this restriction and the following disclaimer,
// must be included in all copies of the Software, in whole or in part, and
// all derivative works of the Software, unless such copies or derivative
// works are solely in the form of machine-executable object code generated by
// a source language processor.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
//
ifndef Foundation_UnbufferedStreamBuf_INCLUDED
define Foundation_UnbufferedStreamBuf_INCLUDED
include "Poco/Foundation.h"
include "Poco/StreamUtil.h"
include <streambuf>
include <iosfwd>
include <ios>
namespace Poco {
template <typename ch, typename tr>
class BasicUnbufferedStreamBuf: public std::basic_streambuf<ch, tr>
This is an implementation of an unbuffered streambuf
that greatly simplifies the implementation of
custom streambufs of various kinds.
Derived classes only have to override the methods
readFromDevice() or writeToDevice().
{
protected:
typedef std::
basic_streambuf<ch, tr> Base;
typedef std::
basic_ios<ch, tr> IOS;
typedef ch char_type;
typedef tr char_traits;
typedef typename Base::int_type int_type;
typedef typename Base::pos_type pos_type;
typedef typename Base::off_type off_type;
typedef typename IOS::openmode openmode;
public:
BasicUnbufferedStreamBuf():
_pb(char_traits::eof()),
_ispb(false)
{
this->setg(0, 0, 0);
this->setp(0, 0);
}
~BasicUnbufferedStreamBuf()
{
}
virtual int_type overflow(int_type c)
{
if (c != char_traits::eof())
return writeToDevice(char_traits::to_char_type(c));
else
return c;
}
virtual int_type underflow()
{
if (_ispb)
{
return _pb;
}
else
{
int_type c = readFromDevice();
if (c != char_traits::eof())
{
_ispb = true;
_pb = c;
}
return c;
}
}
virtual int_type uflow()
{
if (_ispb)
{
_ispb = false;
return _pb;
}
else
{
int_type c = readFromDevice();
if (c != char_traits::eof())
{
_pb = c;
}
return c;
}
}
virtual int_type pbackfail(int_type c)
{
if (_ispb)
{
return char_traits::eof();
}
else
{
_ispb = true;
_pb = c;
return c;
}
}
virtual std::streamsize xsgetn(char_type* p, std::streamsize count)
Some platforms (for example, Compaq C++) have buggy implementations of
xsgetn that handle null buffers incorrectly.
Anyway, it does not hurt to provide an optimized implementation
of xsgetn for this streambuf implementation.
{
std::streamsize copied = 0;
while (count > 0)
{
int_type c = uflow();
if (c == char_traits::eof()) break;
p++ = char_traits::to_char_type(c);
++copied;
--count;
}
return copied;
}
protected:
static int_type charToInt(char_type c)
{
return char_traits::to_int_type(c);
}
private:
virtual int_type readFromDevice()
{
return char_traits::eof();
}
virtual int_type writeToDevice(char_type)
{
return char_traits::eof();
}
int_type _pb;
bool _ispb;
BasicUnbufferedStreamBuf(const BasicUnbufferedStreamBuf&);
BasicUnbufferedStreamBuf& operator = (const BasicUnbufferedStreamBuf&);
};
//
// We provide an instantiation for char
//
typedef BasicUnbufferedStreamBuf<char, std::char_traits<char> > UnbufferedStreamBuf;
} // namespace Poco
endif // Foundation_UnbufferedStreamBuf_INCLUDED
(C) Æliens
04/09/2009
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