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233 lines
6.1 KiB
C++
233 lines
6.1 KiB
C++
//
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// MemoryStream.h
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//
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// Library: Foundation
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// Package: Streams
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// Module: MemoryStream
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//
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// Definition of MemoryStreamBuf, MemoryInputStream, MemoryOutputStream
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//
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// Copyright (c) 2009, 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_MemoryStream_INCLUDED
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#define Foundation_MemoryStream_INCLUDED
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#include <ios>
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#include <iosfwd>
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#include <istream>
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#include <ostream>
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#include <streambuf>
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#include "Poco/Bugcheck.h"
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#include "Poco/Foundation.h"
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#include "Poco/StreamUtil.h"
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namespace Poco
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{
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template <typename ch, typename tr>
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class BasicMemoryStreamBuf : public std::basic_streambuf<ch, tr>
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/// BasicMemoryStreamBuf is a simple implementation of a
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/// stream buffer for reading and writing from a memory area.
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///
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/// This streambuf only supports unidirectional streams.
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/// In other words, the BasicMemoryStreamBuf 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 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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public:
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BasicMemoryStreamBuf(char_type * pBuffer, std::streamsize bufferSize) : _pBuffer(pBuffer), _bufferSize(bufferSize)
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{
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this->setg(_pBuffer, _pBuffer, _pBuffer + _bufferSize);
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this->setp(_pBuffer, _pBuffer + _bufferSize);
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}
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~BasicMemoryStreamBuf() { }
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virtual int_type overflow(int_type /*c*/) { return char_traits::eof(); }
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virtual int_type underflow() { return char_traits::eof(); }
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virtual pos_type
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seekoff(off_type off, std::ios_base::seekdir way, std::ios_base::openmode which = std::ios_base::in | std::ios_base::out)
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{
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const pos_type fail = off_type(-1);
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off_type newoff = off_type(-1);
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if ((which & std::ios_base::in) != 0)
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{
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if (this->gptr() == 0)
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return fail;
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if (way == std::ios_base::beg)
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{
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newoff = 0;
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}
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else if (way == std::ios_base::cur)
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{
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// cur is not valid if both in and out are specified (Condition 3)
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if ((which & std::ios_base::out) != 0)
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return fail;
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newoff = this->gptr() - this->eback();
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}
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else if (way == std::ios_base::end)
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{
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newoff = this->egptr() - this->eback();
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}
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else
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{
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poco_bugcheck();
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}
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if ((newoff + off) < 0 || (this->egptr() - this->eback()) < (newoff + off))
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return fail;
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this->setg(this->eback(), this->eback() + newoff + off, this->egptr());
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}
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if ((which & std::ios_base::out) != 0)
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{
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if (this->pptr() == 0)
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return fail;
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if (way == std::ios_base::beg)
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{
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newoff = 0;
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}
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else if (way == std::ios_base::cur)
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{
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// cur is not valid if both in and out are specified (Condition 3)
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if ((which & std::ios_base::in) != 0)
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return fail;
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newoff = this->pptr() - this->pbase();
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}
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else if (way == std::ios_base::end)
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{
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newoff = this->epptr() - this->pbase();
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}
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else
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{
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poco_bugcheck();
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}
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if (newoff + off < 0 || (this->epptr() - this->pbase()) < newoff + off)
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return fail;
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this->pbump((int)(newoff + off - (this->pptr() - this->pbase())));
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}
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return newoff;
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}
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virtual int sync() { return 0; }
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std::streamsize charsWritten() const { return static_cast<std::streamsize>(this->pptr() - this->pbase()); }
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void reset()
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/// Resets the buffer so that current read and write positions
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/// will be set to the beginning of the buffer.
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{
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this->setg(_pBuffer, _pBuffer, _pBuffer + _bufferSize);
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this->setp(_pBuffer, _pBuffer + _bufferSize);
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}
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private:
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char_type * _pBuffer;
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std::streamsize _bufferSize;
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BasicMemoryStreamBuf();
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BasicMemoryStreamBuf(const BasicMemoryStreamBuf &);
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BasicMemoryStreamBuf & operator=(const BasicMemoryStreamBuf &);
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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 BasicMemoryStreamBuf<char, std::char_traits<char>> MemoryStreamBuf;
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class Foundation_API MemoryIOS : public virtual std::ios
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/// The base class for MemoryInputStream and MemoryOutputStream.
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///
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/// This class is needed to ensure the correct initialization
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/// order of the stream buffer and base classes.
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{
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public:
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MemoryIOS(char * pBuffer, std::streamsize bufferSize);
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/// Creates the basic stream.
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~MemoryIOS();
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/// Destroys the stream.
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MemoryStreamBuf * rdbuf();
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/// Returns a pointer to the underlying streambuf.
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protected:
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MemoryStreamBuf _buf;
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};
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class Foundation_API MemoryInputStream : public MemoryIOS, public std::istream
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/// An input stream for reading from a memory area.
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{
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public:
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MemoryInputStream(const char * pBuffer, std::streamsize bufferSize);
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/// Creates a MemoryInputStream for the given memory area,
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/// ready for reading.
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~MemoryInputStream();
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/// Destroys the MemoryInputStream.
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};
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class Foundation_API MemoryOutputStream : public MemoryIOS, public std::ostream
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/// An input stream for reading from a memory area.
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{
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public:
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MemoryOutputStream(char * pBuffer, std::streamsize bufferSize);
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/// Creates a MemoryOutputStream for the given memory area,
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/// ready for writing.
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~MemoryOutputStream();
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/// Destroys the MemoryInputStream.
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std::streamsize charsWritten() const;
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/// Returns the number of chars written to the buffer.
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};
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//
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// inlines
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//
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inline MemoryStreamBuf * MemoryIOS::rdbuf()
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{
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return &_buf;
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}
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inline std::streamsize MemoryOutputStream::charsWritten() const
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{
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return _buf.charsWritten();
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}
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} // namespace Poco
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#endif // Foundation_MemoryStream_INCLUDED
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