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//
// MemoryStream.h
//
// Library: Foundation
// Package: Streams
// Module: MemoryStream
//
// Definition of MemoryStreamBuf, MemoryInputStream, MemoryOutputStream
//
// Copyright (c) 2009, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// SPDX-License-Identifier: BSL-1.0
//
#ifndef Foundation_MemoryStream_INCLUDED
#define Foundation_MemoryStream_INCLUDED
#include "Poco/Bugcheck.h"
#include "Poco/Foundation.h"
#include "Poco/StreamUtil.h"
#include <streambuf>
#include <iosfwd>
#include <ios>
#include <istream>
#include <ostream>
namespace Poco {
template <typename ch, typename tr>
class BasicMemoryStreamBuf: public std::basic_streambuf<ch, tr>
/// BasicMemoryStreamBuf is a simple implementation of a
/// stream buffer for reading and writing from a memory area.
///
/// This streambuf only supports unidirectional streams.
/// In other words, the BasicMemoryStreamBuf can be
/// used for the implementation of an istream or an
/// ostream, but not for an iostream.
{
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;
public:
BasicMemoryStreamBuf(char_type* pBuffer, std::streamsize bufferSize):
_pBuffer(pBuffer),
_bufferSize(bufferSize)
{
this->setg(_pBuffer, _pBuffer, _pBuffer + _bufferSize);
this->setp(_pBuffer, _pBuffer + _bufferSize);
}
~BasicMemoryStreamBuf()
{
}
virtual int_type overflow(int_type /*c*/)
{
return char_traits::eof();
}
virtual int_type underflow()
{
return char_traits::eof();
}
virtual pos_type seekoff(off_type off, std::ios_base::seekdir way, std::ios_base::openmode which = std::ios_base::in | std::ios_base::out)
{
const pos_type fail = off_type(-1);
off_type newoff = off_type(-1);
if ((which & std::ios_base::in) != 0)
{
if (this->gptr() == 0)
return fail;
if (way == std::ios_base::beg)
{
newoff = 0;
}
else if (way == std::ios_base::cur)
{
// cur is not valid if both in and out are specified (Condition 3)
if ((which & std::ios_base::out) != 0)
return fail;
newoff = this->gptr() - this->eback();
}
else if (way == std::ios_base::end)
{
newoff = this->egptr() - this->eback();
}
else
{
poco_bugcheck();
}
if ((newoff + off) < 0 || (this->egptr() - this->eback()) < (newoff + off))
return fail;
this->setg(this->eback(), this->eback() + newoff + off, this->egptr());
}
if ((which & std::ios_base::out) != 0)
{
if (this->pptr() == 0)
return fail;
if (way == std::ios_base::beg)
{
newoff = 0;
}
else if (way == std::ios_base::cur)
{
// cur is not valid if both in and out are specified (Condition 3)
if ((which & std::ios_base::in) != 0)
return fail;
newoff = this->pptr() - this->pbase();
}
else if (way == std::ios_base::end)
{
newoff = this->epptr() - this->pbase();
}
else
{
poco_bugcheck();
}
if (newoff + off < 0 || (this->epptr() - this->pbase()) < newoff + off)
return fail;
this->pbump((int)(newoff + off - (this->pptr() - this->pbase())));
}
return newoff;
}
virtual int sync()
{
return 0;
}
std::streamsize charsWritten() const
{
return static_cast<std::streamsize>(this->pptr() - this->pbase());
}
void reset()
/// Resets the buffer so that current read and write positions
/// will be set to the beginning of the buffer.
{
this->setg(_pBuffer, _pBuffer, _pBuffer + _bufferSize);
this->setp(_pBuffer, _pBuffer + _bufferSize);
}
private:
char_type* _pBuffer;
std::streamsize _bufferSize;
BasicMemoryStreamBuf();
BasicMemoryStreamBuf(const BasicMemoryStreamBuf&);
BasicMemoryStreamBuf& operator = (const BasicMemoryStreamBuf&);
};
//
// We provide an instantiation for char
//
typedef BasicMemoryStreamBuf<char, std::char_traits<char> > MemoryStreamBuf;
class Foundation_API MemoryIOS: public virtual std::ios
/// The base class for MemoryInputStream and MemoryOutputStream.
///
/// This class is needed to ensure the correct initialization
/// order of the stream buffer and base classes.
{
public:
MemoryIOS(char* pBuffer, std::streamsize bufferSize);
/// Creates the basic stream.
~MemoryIOS();
/// Destroys the stream.
MemoryStreamBuf* rdbuf();
/// Returns a pointer to the underlying streambuf.
protected:
MemoryStreamBuf _buf;
};
class Foundation_API MemoryInputStream: public MemoryIOS, public std::istream
/// An input stream for reading from a memory area.
{
public:
MemoryInputStream(const char* pBuffer, std::streamsize bufferSize);
/// Creates a MemoryInputStream for the given memory area,
/// ready for reading.
~MemoryInputStream();
/// Destroys the MemoryInputStream.
};
class Foundation_API MemoryOutputStream: public MemoryIOS, public std::ostream
/// An input stream for reading from a memory area.
{
public:
MemoryOutputStream(char* pBuffer, std::streamsize bufferSize);
/// Creates a MemoryOutputStream for the given memory area,
/// ready for writing.
~MemoryOutputStream();
/// Destroys the MemoryInputStream.
std::streamsize charsWritten() const;
/// Returns the number of chars written to the buffer.
};
//
// inlines
//
inline MemoryStreamBuf* MemoryIOS::rdbuf()
{
return &_buf;
}
inline std::streamsize MemoryOutputStream::charsWritten() const
{
return _buf.charsWritten();
}
} // namespace Poco
#endif // Foundation_MemoryStream_INCLUDED
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