Code:
/ Dotnetfx_Win7_3.5.1 / Dotnetfx_Win7_3.5.1 / 3.5.1 / WIN_WINDOWS / lh_tools_devdiv_wpf / Windows / wcp / Speech / Src / Internal / SeekableReadStream.cs / 1 / SeekableReadStream.cs
//----------------------------------------------------------------------------
//
// Copyright (C) Microsoft Corporation. All rights reserved.
//
//---------------------------------------------------------------------------
using System;
using System.IO;
using System.Collections.Generic;
using System.Diagnostics;
#pragma warning disable 1634, 1691 // Allows suppression of certain PreSharp messages.
namespace System.Speech.Internal
{
#pragma warning disable 56528 // Override of Dispose(bool) not needed as base stream should not be closed.
// Class that is used to wrap a stream that does not support Seek into one that does.
// While CacheDataForSeeking is true then Read data is buffered so that Seeking can be done later back into the buffer.
// The Read call will first use the buffer and then the actual data once the buffer is read.
// After CacheDataForSeeking is set to false data can be read from the buffer but no more Seeking can be done.
internal class SeekableReadStream : Stream
{
//*******************************************************************
//
// Constructors
//
//*******************************************************************
#region Constructors
internal SeekableReadStream(Stream baseStream)
{
Debug.Assert(baseStream.CanRead);
_canSeek = baseStream.CanSeek; // If the stream is already seekable then don't need to do anything special
_baseStream = baseStream;
}
#endregion
//********************************************************************
//
// Internal Properties
//
//*******************************************************************
#region Internal Properties
internal bool CacheDataForSeeking
{
set
{
// Currently we can switch the caching off, but not back on again. Not needed for current scenarios.
Debug.Assert(!value || _cacheDataForSeeking);
_cacheDataForSeeking = value;
}
}
public override bool CanRead
{
get { return true; }
}
public override bool CanSeek
{
get
{
// Can do seeking only if we are caching data or underlying stream supports it.
return (_canSeek || _cacheDataForSeeking);
}
}
public override bool CanWrite
{
get { return false; }
}
public override long Length
{
// Non Seekable streams may not implement this, but we don't have much choice as we can't calculate the Stream length any other way.
get { return _baseStream.Length; }
}
public override long Position
{
get
{
if (_canSeek)
{
// Delegate to underlying Stream:
return _baseStream.Position;
}
else
{
return _virtualPosition;
}
}
set
{
if (_canSeek)
{
// Delegate to underlying Stream:
_baseStream.Position = value;
}
else if (value != _virtualPosition)
{
if (value < 0)
{
throw new ArgumentOutOfRangeException("value", SR.Get(SRID.MustBeGreaterThanZero));
}
// We can't check the length here so you can Seek beyond the end of the Stream. This will error later though.
if (_cacheDataForSeeking)
{
if (value < _buffer.Count)
{
// We're moving within the already buffered data so just move the position:
_virtualPosition = value;
}
else
{
// We're moving beyond current position.
// Thus Read the new data data and buffer it.
// Read until at new position:
long bytesToReadLong = value - _buffer.Count;
if (bytesToReadLong > int.MaxValue)
{
throw new NotSupportedException(SR.Get(SRID.SeekNotSupported));
}
byte[] readBuffer = new byte[bytesToReadLong];
Helpers.BlockingRead(_baseStream, readBuffer, 0, (int)bytesToReadLong);
// Copy from readBuffer into cache:
_buffer.AddRange(readBuffer);
_virtualPosition = value;
}
}
else
{
// No longer caching data so we can't seek around.
// Limited cases of this could be supported if needed.
throw new NotSupportedException(SR.Get(SRID.SeekNotSupported));
}
}
}
}
#endregion
//********************************************************************
//
// Internal Methods
//
//********************************************************************
#region Internal Methods
public override int Read(byte[] buffer, int offset, int count)
{
if (_canSeek)
{
// Delegate to underlying Stream:
return _baseStream.Read(buffer, offset, count);
}
else
{
int bytesRead = 0;
if (_virtualPosition < _buffer.Count)
{
// if new position inside buffer then read until at end of buffer
int toCopy = (int)(_buffer.Count - _virtualPosition);
if (toCopy > count)
{
toCopy = count;
}
_buffer.CopyTo((int)_virtualPosition, buffer, offset, toCopy);
count -= toCopy;
_virtualPosition += toCopy;
offset += toCopy;
bytesRead += toCopy;
if (!_cacheDataForSeeking && _virtualPosition >= _buffer.Count)
{
// Used up all the buffer, free.
_buffer.Clear();
}
}
if (count > 0)
{
// Still data to Read so read it from the base Stream:
int localBytesRead = _baseStream.Read(buffer, offset, count);
bytesRead += localBytesRead;
_virtualPosition += localBytesRead;
if (_cacheDataForSeeking)
{
// if caching then extend Stream.
_buffer.Capacity += localBytesRead;
// Copy from buffer + offset for bytesRead
for (int i = 0; i < localBytesRead; i++)
{
_buffer.Add(buffer[offset + i]);
}
}
// Even if we didn't read every requested byte we can return - that's the contract on Stream.Read.
}
return bytesRead;
}
}
public override long Seek(long offset, SeekOrigin origin)
{
long position;
checked // Check for integer overflow
{
switch (origin)
{
case SeekOrigin.Begin:
position = offset;
break;
case SeekOrigin.Current:
position = Position + offset;
break;
case SeekOrigin.End:
position = Length + offset;
break;
default:
throw new ArgumentException(SR.Get(SRID.EnumInvalid, "SeekOrigin"), "origin");
}
}
Position = position; // Actually update position, checks for out of range
return position;
}
public override void SetLength(long value)
{
throw new NotSupportedException(SR.Get(SRID.SeekNotSupported));
}
public override void Write(byte[] buffer, int offset, int count)
{
throw new NotSupportedException(SR.Get(SRID.StreamMustBeWriteable));
}
public override void Flush()
{
_baseStream.Flush();
}
#endregion
//*******************************************************************
//
// Private Fields
//
//********************************************************************
#region Private Fields
private long _virtualPosition;
private List _buffer = new List(); // Data cached from start of stream onwards.
private Stream _baseStream;
private bool _cacheDataForSeeking = true;
private bool _canSeek;
#endregion
}
#pragma warning restore 56528
}
// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
//----------------------------------------------------------------------------
//
// Copyright (C) Microsoft Corporation. All rights reserved.
//
//---------------------------------------------------------------------------
using System;
using System.IO;
using System.Collections.Generic;
using System.Diagnostics;
#pragma warning disable 1634, 1691 // Allows suppression of certain PreSharp messages.
namespace System.Speech.Internal
{
#pragma warning disable 56528 // Override of Dispose(bool) not needed as base stream should not be closed.
// Class that is used to wrap a stream that does not support Seek into one that does.
// While CacheDataForSeeking is true then Read data is buffered so that Seeking can be done later back into the buffer.
// The Read call will first use the buffer and then the actual data once the buffer is read.
// After CacheDataForSeeking is set to false data can be read from the buffer but no more Seeking can be done.
internal class SeekableReadStream : Stream
{
//*******************************************************************
//
// Constructors
//
//*******************************************************************
#region Constructors
internal SeekableReadStream(Stream baseStream)
{
Debug.Assert(baseStream.CanRead);
_canSeek = baseStream.CanSeek; // If the stream is already seekable then don't need to do anything special
_baseStream = baseStream;
}
#endregion
//********************************************************************
//
// Internal Properties
//
//*******************************************************************
#region Internal Properties
internal bool CacheDataForSeeking
{
set
{
// Currently we can switch the caching off, but not back on again. Not needed for current scenarios.
Debug.Assert(!value || _cacheDataForSeeking);
_cacheDataForSeeking = value;
}
}
public override bool CanRead
{
get { return true; }
}
public override bool CanSeek
{
get
{
// Can do seeking only if we are caching data or underlying stream supports it.
return (_canSeek || _cacheDataForSeeking);
}
}
public override bool CanWrite
{
get { return false; }
}
public override long Length
{
// Non Seekable streams may not implement this, but we don't have much choice as we can't calculate the Stream length any other way.
get { return _baseStream.Length; }
}
public override long Position
{
get
{
if (_canSeek)
{
// Delegate to underlying Stream:
return _baseStream.Position;
}
else
{
return _virtualPosition;
}
}
set
{
if (_canSeek)
{
// Delegate to underlying Stream:
_baseStream.Position = value;
}
else if (value != _virtualPosition)
{
if (value < 0)
{
throw new ArgumentOutOfRangeException("value", SR.Get(SRID.MustBeGreaterThanZero));
}
// We can't check the length here so you can Seek beyond the end of the Stream. This will error later though.
if (_cacheDataForSeeking)
{
if (value < _buffer.Count)
{
// We're moving within the already buffered data so just move the position:
_virtualPosition = value;
}
else
{
// We're moving beyond current position.
// Thus Read the new data data and buffer it.
// Read until at new position:
long bytesToReadLong = value - _buffer.Count;
if (bytesToReadLong > int.MaxValue)
{
throw new NotSupportedException(SR.Get(SRID.SeekNotSupported));
}
byte[] readBuffer = new byte[bytesToReadLong];
Helpers.BlockingRead(_baseStream, readBuffer, 0, (int)bytesToReadLong);
// Copy from readBuffer into cache:
_buffer.AddRange(readBuffer);
_virtualPosition = value;
}
}
else
{
// No longer caching data so we can't seek around.
// Limited cases of this could be supported if needed.
throw new NotSupportedException(SR.Get(SRID.SeekNotSupported));
}
}
}
}
#endregion
//********************************************************************
//
// Internal Methods
//
//********************************************************************
#region Internal Methods
public override int Read(byte[] buffer, int offset, int count)
{
if (_canSeek)
{
// Delegate to underlying Stream:
return _baseStream.Read(buffer, offset, count);
}
else
{
int bytesRead = 0;
if (_virtualPosition < _buffer.Count)
{
// if new position inside buffer then read until at end of buffer
int toCopy = (int)(_buffer.Count - _virtualPosition);
if (toCopy > count)
{
toCopy = count;
}
_buffer.CopyTo((int)_virtualPosition, buffer, offset, toCopy);
count -= toCopy;
_virtualPosition += toCopy;
offset += toCopy;
bytesRead += toCopy;
if (!_cacheDataForSeeking && _virtualPosition >= _buffer.Count)
{
// Used up all the buffer, free.
_buffer.Clear();
}
}
if (count > 0)
{
// Still data to Read so read it from the base Stream:
int localBytesRead = _baseStream.Read(buffer, offset, count);
bytesRead += localBytesRead;
_virtualPosition += localBytesRead;
if (_cacheDataForSeeking)
{
// if caching then extend Stream.
_buffer.Capacity += localBytesRead;
// Copy from buffer + offset for bytesRead
for (int i = 0; i < localBytesRead; i++)
{
_buffer.Add(buffer[offset + i]);
}
}
// Even if we didn't read every requested byte we can return - that's the contract on Stream.Read.
}
return bytesRead;
}
}
public override long Seek(long offset, SeekOrigin origin)
{
long position;
checked // Check for integer overflow
{
switch (origin)
{
case SeekOrigin.Begin:
position = offset;
break;
case SeekOrigin.Current:
position = Position + offset;
break;
case SeekOrigin.End:
position = Length + offset;
break;
default:
throw new ArgumentException(SR.Get(SRID.EnumInvalid, "SeekOrigin"), "origin");
}
}
Position = position; // Actually update position, checks for out of range
return position;
}
public override void SetLength(long value)
{
throw new NotSupportedException(SR.Get(SRID.SeekNotSupported));
}
public override void Write(byte[] buffer, int offset, int count)
{
throw new NotSupportedException(SR.Get(SRID.StreamMustBeWriteable));
}
public override void Flush()
{
_baseStream.Flush();
}
#endregion
//*******************************************************************
//
// Private Fields
//
//********************************************************************
#region Private Fields
private long _virtualPosition;
private List _buffer = new List(); // Data cached from start of stream onwards.
private Stream _baseStream;
private bool _cacheDataForSeeking = true;
private bool _canSeek;
#endregion
}
#pragma warning restore 56528
}
// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
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