genesis-3d_engine/Engine/foundation/io/stream.cc

/****************************************************************************
Copyright (c) 2006, Radon Labs GmbH
Copyright (c) 2011-2013,WebJet Business Division,CYOU
 
http://www.genesis-3d.com.cn

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

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 AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
****************************************************************************/
#include "stdneb.h"
#include "io/stream.h"

namespace IO
{
__ImplementClass(IO::Stream, 'STRM', Core::RefCounted);

using namespace Util;

//------------------------------------------------------------------------------
/**
*/
Stream::Stream() :
    accessMode(ReadAccess),
    accessPattern(Sequential),
    isOpen(false),
    isMapped(false)
{
    // empty
}

//------------------------------------------------------------------------------
/**
*/
Stream::~Stream()
{
    n_assert(!this->IsOpen());
    n_assert(!this->IsMapped());
}

//------------------------------------------------------------------------------
/**
    Set the URI of the stream as string. The URI identifies the source
    resource of the stream.
*/
void
Stream::SetURI(const URI& u)
{
    n_assert(!this->IsOpen());
    this->uri = u;
}

//------------------------------------------------------------------------------
/**
    Get the URI of the stream as string.
*/
const URI&
Stream::GetURI() const
{
    return this->uri;
}

//------------------------------------------------------------------------------
/**
    This method must return true if the derived stream class supports reading.
*/
bool
Stream::CanRead() const
{
    return false;
}

//------------------------------------------------------------------------------
/**
    This method must return true if the derived stream class supports writing.
*/
bool
Stream::CanWrite() const
{
    return false;
}

//------------------------------------------------------------------------------
/**
    This method must return true if the derived stream supports seeking.
*/
bool
Stream::CanSeek() const
{
    return false;
}

//------------------------------------------------------------------------------
/**
    This method must return true if the stream supports direct memory
    access through the Map()/Unmap() methods.
*/
bool
Stream::CanBeMapped() const
{
    return false;
}

//------------------------------------------------------------------------------
/**
    This sets a new size for the stream. Not all streams support this method.
    If the new size if smaller then the existing size, the contents will
    be clipped.
*/
void
Stream::SetSize(Size /*s*/)
{
    n_assert(!this->IsOpen());
}

//------------------------------------------------------------------------------
/**
    This method returns the size of the stream in bytes.
*/
Stream::Size
Stream::GetSize() const
{
    return 0;
}

//------------------------------------------------------------------------------
/**
    This method returns the current position of the read/write cursor.
*/
Stream::Position
Stream::GetPosition() const
{
    return 0;
}

//------------------------------------------------------------------------------
/**
    This method sets the intended access mode of the stream. The actual
    behaviour depends on the implementation of the derived class. The
    default is ReadWrite.
*/
void
Stream::SetAccessMode(AccessMode m)
{
    n_assert(!this->IsOpen());
    this->accessMode = m;
}

//------------------------------------------------------------------------------
/**
    Get the access mode of the stream.
*/
Stream::AccessMode
Stream::GetAccessMode() const
{
    return this->accessMode;
}

//------------------------------------------------------------------------------
/**
    Set the prefered access pattern of the stream. This can be Random or
    Sequential. This is an optional flag to improve performance with
    some stream implementations. The default is sequential. The pattern
    cannot be changed while the stream is open.
*/
void
Stream::SetAccessPattern(AccessPattern p)
{
    n_assert(!this->IsOpen());
    this->accessPattern = p;
}

//------------------------------------------------------------------------------
/**
    Get the currently set prefered access pattern of the stream.
*/
Stream::AccessPattern
Stream::GetAccessPattern() const
{
    return this->accessPattern;
}

//------------------------------------------------------------------------------
/**
*/
void
Stream::SetMediaType(const MediaType& t)
{
    this->mediaType = t;
}

//------------------------------------------------------------------------------
/**
*/
const MediaType&
Stream::GetMediaType() const
{
    return this->mediaType;
}

//------------------------------------------------------------------------------
/**
    Open the stream. Only one thread may open a stream at any time.
    Returns true if succeeded.
*/
bool
Stream::Open()
{
    n_assert(!this->IsOpen());
    this->isOpen = true;
    return true;
}

//------------------------------------------------------------------------------
/**
    Closes the stream.
*/
void
Stream::Close()
{
    n_assert(this->IsOpen());
    this->isOpen = false;
}

//------------------------------------------------------------------------------
/**
    Return true if the stream is currently open.
*/
bool
Stream::IsOpen() const
{
    return this->isOpen;
}

//------------------------------------------------------------------------------
/**
    Write raw data to the stream. For more convenient writing, attach the
    stream to an IO::StreamWriter object. This method is only valid if the 
    stream class returns true in CanWrite().
*/
void
Stream::Write(const void* /*ptr*/, Size /*numBytes*/)
{
    n_assert(this->IsOpen());
    n_assert(!this->isMapped);
}

//------------------------------------------------------------------------------
/**
    Read raw data from the stream. For more convenient reading, attach
    the stream to an IO::StreamReader object. The method returns the number
    of bytes actually read. This method is only valid if the stream
    class returns true in CanRead(). Returns the number of bytes actually
    read from the stream, this may be less then numBytes, or 0 if end-of-stream
    is reached.
*/
Stream::Size
Stream::Read(void* /*ptr*/, Size /*numBytes*/)
{
    n_assert(this->IsOpen());
    n_assert(!this->isMapped);
    return 0;
}

//------------------------------------------------------------------------------
/**
    Move the read/write cursor to a new position, returns the new position
    in the stream. This method is only supported if the stream class
    returns true in CanSeek().
*/
void
Stream::Seek(Offset /*offset*/, SeekOrigin /*origin*/)
{
    n_assert(this->IsOpen());
    n_assert(!this->isMapped);
}

//------------------------------------------------------------------------------
/**
    Flush any unsaved data. Note that unsaved data will also be flushed
    automatically when the stream is closed.
*/
void
Stream::Flush()
{
    n_assert(this->IsOpen());
    n_assert(!this->isMapped);
}

//------------------------------------------------------------------------------
/**
    Return true if the read/write cursor is at the end of the stream.
*/
bool
Stream::Eof() const
{
    n_assert(this->IsOpen());
    n_assert(!this->isMapped);
    return true;
}

//------------------------------------------------------------------------------
/**
    If the stream provides memory mapping, this method will return a pointer
    to the beginning of the stream data in memory. The application is 
    free to read and write to the stream through direct memory access. Special
    care must be taken to not read or write past the end of the mapped data
    (indicated by GetSize()). The normal Read()/Write() method are not
    valid while the stream is mapped, also the read/write cursor position
    will not be updated.
*/
void*
Stream::Map()
{
    n_assert(this->IsOpen());
    n_assert(this->CanBeMapped());
    n_assert(!this->isMapped);
    this->isMapped = true;
    return 0;
}

//------------------------------------------------------------------------------
/**
    This will unmap a memory-mapped stream.
*/
void
Stream::Unmap()
{
    n_assert(this->IsOpen());
    n_assert(this->CanBeMapped());
    n_assert(this->isMapped);
    this->isMapped = false;
}

//------------------------------------------------------------------------------
/**
    just copy some data to memory,not so many check!
*/
Stream::Size
Stream::Copy( void* ptr, Size numBytes )const
{
	return 0;
}

//------------------------------------------------------------------------------
/**
    Returns true if the stream is currently mapped.
*/
bool
Stream::IsMapped() const
{
    return this->isMapped;
}

//-------------------------------------------------------------------------
bool
	Stream::IsHeader( void* headPtr, Size numBytes )
{
	n_error("derived class must implement!");
	return false;
}

} // namespace IO