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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
using System;
using System.Collections.Immutable;
using System.Diagnostics;
using System.IO;
namespace Microsoft.CodeAnalysis.Collections
{
internal sealed class ImmutableMemoryStream : Stream
{
private readonly ImmutableArray<byte> _array;
private int _position;
internal ImmutableMemoryStream(ImmutableArray<byte> array)
{
Debug.Assert(!array.IsDefault);
_array = array;
}
public ImmutableArray<byte> GetBuffer()
{
return _array;
}
public override bool CanRead
{
get { return true; }
}
public override bool CanSeek
{
get { return true; }
}
public override bool CanWrite
{
get { return false; }
}
public override long Length
{
get { return _array.Length; }
}
public override long Position
{
get
{
return _position;
}
set
{
if (value < 0 || value >= _array.Length)
{
throw new ArgumentOutOfRangeException(nameof(value));
}
_position = (int)value;
}
}
public override void Flush()
{
}
public override int Read(byte[] buffer, int offset, int count)
{
int result = Math.Min(count, _array.Length - _position);
_array.CopyTo(_position, buffer, offset, result);
_position += result;
return result;
}
public override long Seek(long offset, SeekOrigin origin)
{
long target;
try
{
switch (origin)
{
case SeekOrigin.Begin:
target = offset;
break;
case SeekOrigin.Current:
target = checked(offset + _position);
break;
case SeekOrigin.End:
target = checked(offset + _array.Length);
break;
default:
throw new ArgumentOutOfRangeException(nameof(origin));
}
}
catch (OverflowException)
{
throw new ArgumentOutOfRangeException(nameof(offset));
}
if (target < 0 || target >= _array.Length)
{
throw new ArgumentOutOfRangeException(nameof(offset));
}
_position = (int)target;
return target;
}
public override void SetLength(long value)
{
throw new NotSupportedException();
}
public override void Write(byte[] buffer, int offset, int count)
{
throw new NotSupportedException();
}
}
}
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