175 строки
3.3 KiB
C++
175 строки
3.3 KiB
C++
//
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// UnufferedStreamBuf.h
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//
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// $Id: //poco/1.4/Foundation/include/Poco/UnbufferedStreamBuf.h#1 $
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//
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// Library: Foundation
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// Package: Streams
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// Module: StreamBuf
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//
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// Definition of template BasicUnbufferedStreamBuf and class UnbufferedStreamBuf.
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//
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// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
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// and Contributors.
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//
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// SPDX-License-Identifier: BSL-1.0
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//
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#ifndef Foundation_UnbufferedStreamBuf_INCLUDED
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#define Foundation_UnbufferedStreamBuf_INCLUDED
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#include "Poco/Foundation.h"
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#include "Poco/StreamUtil.h"
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#include <streambuf>
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#include <iosfwd>
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#include <ios>
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namespace Poco {
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template <typename ch, typename tr>
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class BasicUnbufferedStreamBuf: public std::basic_streambuf<ch, tr>
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/// This is an implementation of an unbuffered streambuf
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/// that greatly simplifies the implementation of
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/// custom streambufs of various kinds.
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/// Derived classes only have to override the methods
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/// readFromDevice() or writeToDevice().
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{
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protected:
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typedef std::basic_streambuf<ch, tr> Base;
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typedef std::basic_ios<ch, tr> IOS;
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typedef ch char_type;
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typedef tr char_traits;
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typedef typename Base::int_type int_type;
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typedef typename Base::pos_type pos_type;
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typedef typename Base::off_type off_type;
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typedef typename IOS::openmode openmode;
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public:
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BasicUnbufferedStreamBuf():
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_pb(char_traits::eof()),
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_ispb(false)
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{
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this->setg(0, 0, 0);
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this->setp(0, 0);
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}
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~BasicUnbufferedStreamBuf()
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{
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}
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virtual int_type overflow(int_type c)
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{
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if (c != char_traits::eof())
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return writeToDevice(char_traits::to_char_type(c));
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else
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return c;
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}
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virtual int_type underflow()
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{
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if (_ispb)
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{
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return _pb;
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}
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else
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{
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int_type c = readFromDevice();
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if (c != char_traits::eof())
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{
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_ispb = true;
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_pb = c;
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}
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return c;
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}
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}
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virtual int_type uflow()
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{
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if (_ispb)
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{
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_ispb = false;
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return _pb;
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}
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else
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{
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int_type c = readFromDevice();
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if (c != char_traits::eof())
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{
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_pb = c;
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}
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return c;
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}
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}
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virtual int_type pbackfail(int_type c)
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{
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if (_ispb)
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{
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return char_traits::eof();
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}
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else
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{
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_ispb = true;
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_pb = c;
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return c;
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}
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}
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virtual std::streamsize xsgetn(char_type* p, std::streamsize count)
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/// Some platforms (for example, Compaq C++) have buggy implementations of
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/// xsgetn that handle null buffers incorrectly.
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/// Anyway, it does not hurt to provide an optimized implementation
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/// of xsgetn for this streambuf implementation.
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{
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std::streamsize copied = 0;
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while (count > 0)
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{
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int_type c = uflow();
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if (c == char_traits::eof()) break;
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*p++ = char_traits::to_char_type(c);
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++copied;
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--count;
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}
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return copied;
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}
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protected:
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static int_type charToInt(char_type c)
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{
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return char_traits::to_int_type(c);
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}
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private:
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virtual int_type readFromDevice()
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{
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return char_traits::eof();
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}
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virtual int_type writeToDevice(char_type)
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{
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return char_traits::eof();
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}
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int_type _pb;
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bool _ispb;
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BasicUnbufferedStreamBuf(const BasicUnbufferedStreamBuf&);
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BasicUnbufferedStreamBuf& operator = (const BasicUnbufferedStreamBuf&);
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};
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//
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// We provide an instantiation for char
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//
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typedef BasicUnbufferedStreamBuf<char, std::char_traits<char> > UnbufferedStreamBuf;
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} // namespace Poco
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#endif // Foundation_UnbufferedStreamBuf_INCLUDED
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