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175 lines
4.8 KiB
C++
175 lines
4.8 KiB
C++
//
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// BufferedStreamBuf.h
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//
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// $Id: //poco/Main/Foundation/include/Poco/BufferedStreamBuf.h#2 $
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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 BasicBufferedStreamBuf and class BufferedStreamBuf.
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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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// Permission is hereby granted, free of charge, to any person or organization
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// obtaining a copy of the software and accompanying documentation covered by
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// this license (the "Software") to use, reproduce, display, distribute,
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// execute, and transmit the Software, and to prepare derivative works of the
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// Software, and to permit third-parties to whom the Software is furnished to
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// do so, all subject to the following:
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//
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// The copyright notices in the Software and this entire statement, including
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// the above license grant, this restriction and the following disclaimer,
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// must be included in all copies of the Software, in whole or in part, and
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// all derivative works of the Software, unless such copies or derivative
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// works are solely in the form of machine-executable object code generated by
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// a source language processor.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
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// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
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// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
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// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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// DEALINGS IN THE SOFTWARE.
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//
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#ifndef Foundation_BufferedStreamBuf_INCLUDED
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#define Foundation_BufferedStreamBuf_INCLUDED
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#include "Poco/Foundation.h"
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#include "Poco/BufferAllocator.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, typename ba = BufferAllocator<ch> >
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class BasicBufferedStreamBuf: public std::basic_streambuf<ch, tr>
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/// This is an implementation of a buffered 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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/// This streambuf only supports unidirectional streams.
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/// In other words, the BasicBufferedStreamBuf can be
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/// used for the implementation of an istream or an
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/// ostream, but not for an iostream.
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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 ba Allocator;
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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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BasicBufferedStreamBuf(std::streamsize bufferSize, openmode mode):
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_bufsize(bufferSize),
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_pBuffer(Allocator::allocate(_bufsize)),
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_mode(mode)
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{
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this->setg(_pBuffer + 4, _pBuffer + 4, _pBuffer + 4);
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this->setp(_pBuffer, _pBuffer + (_bufsize - 1));
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}
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~BasicBufferedStreamBuf()
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{
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Allocator::deallocate(_pBuffer, _bufsize);
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}
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virtual int_type overflow(int_type c)
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{
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if (!(_mode & IOS::out)) return char_traits::eof();
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if (c != char_traits::eof())
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{
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*this->pptr() = char_traits::to_char_type(c);
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this->pbump(1);
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}
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if (flush_buffer() == std::streamsize(-1)) return char_traits::eof();
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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 (!(_mode & IOS::in)) return char_traits::eof();
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if (this->gptr() && (this->gptr() < this->egptr()))
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return char_traits::to_int_type(*this->gptr());
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int putback = int(this->gptr() - this->eback());
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if (putback > 4) putback = 4;
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char_traits::copy(_pBuffer + (4 - putback), this->gptr() - putback, putback);
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int n = readFromDevice(_pBuffer + 4, _bufsize - 4);
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if (n <= 0) return char_traits::eof();
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this->setg(_pBuffer + (4 - putback), _pBuffer + 4, _pBuffer + 4 + n);
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// return next character
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return char_traits::to_int_type(*this->gptr());
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}
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virtual int sync()
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{
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if (this->pptr() && this->pptr() > this->pbase())
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{
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if (flush_buffer() == -1) return -1;
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}
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return 0;
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}
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private:
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virtual int readFromDevice(char_type* buffer, std::streamsize length)
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{
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return 0;
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}
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virtual int writeToDevice(const char_type* buffer, std::streamsize length)
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{
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return 0;
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}
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int flush_buffer()
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{
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int n = int(this->pptr() - this->pbase());
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if (writeToDevice(this->pbase(), n) == n)
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{
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this->pbump(-n);
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return n;
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}
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return -1;
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}
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std::streamsize _bufsize;
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char_type* _pBuffer;
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openmode _mode;
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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 BasicBufferedStreamBuf<char, std::char_traits<char> > BufferedStreamBuf;
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} // namespace Poco
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#endif // Foundation_BufferedStreamBuf_INCLUDED
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