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/*
* [The "BSD licence"]
* Copyright (c) 2005-2008 Terence Parr
* All rights reserved.
*
* Conversion to C#:
* Copyright (c) 2008-2009 Sam Harwell, Pixel Mine, Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
namespace Antlr.Runtime
{
using System.Collections.Generic;
using InvalidOperationException = System.InvalidOperationException;
using StringBuilder = System.Text.StringBuilder;
/** <summary>
* The most common stream of tokens is one where every token is buffered up
* and tokens are prefiltered for a certain channel (the parser will only
* see these tokens and cannot change the filter channel number during the
* parse).
* </summary>
*
* <remarks>TODO: how to access the full token stream? How to track all tokens matched per rule?</remarks>
*/
[System.Serializable]
public class CommonTokenStream : BufferedTokenStream
{
/** Skip tokens on any channel but this one; this is how we skip whitespace... */
private int _channel;
public CommonTokenStream()
{
}
public CommonTokenStream(ITokenSource tokenSource)
: this(tokenSource, TokenChannels.Default)
{
}
public CommonTokenStream(ITokenSource tokenSource, int channel)
: base(tokenSource)
{
this._channel = channel;
}
public int Channel
{
get
{
return _channel;
}
}
/** Reset this token stream by setting its token source. */
public override ITokenSource TokenSource
{
get
{
return base.TokenSource;
}
set
{
base.TokenSource = value;
_channel = TokenChannels.Default;
}
}
/** Always leave p on an on-channel token. */
public override void Consume()
{
if (_p == -1)
Setup();
_p++;
_p = SkipOffTokenChannels(_p);
}
protected override IToken LB(int k)
{
if (k == 0 || (_p - k) < 0)
return null;
int i = _p;
int n = 1;
// find k good tokens looking backwards
while (n <= k)
{
// skip off-channel tokens
i = SkipOffTokenChannelsReverse(i - 1);
n++;
}
if (i < 0)
return null;
return _tokens[i];
}
public override IToken LT(int k)
{
if (_p == -1)
Setup();
if (k == 0)
return null;
if (k < 0)
return LB(-k);
int i = _p;
int n = 1; // we know tokens[p] is a good one
// find k good tokens
while (n < k)
{
// skip off-channel tokens
i = SkipOffTokenChannels(i + 1);
n++;
}
if (i > Range)
Range = i;
return _tokens[i];
}
/** Given a starting index, return the index of the first on-channel
* token.
*/
protected virtual int SkipOffTokenChannels(int i)
{
Sync(i);
while (_tokens[i].Channel != _channel)
{
// also stops at EOF (it's on channel)
i++;
Sync(i);
}
return i;
}
protected virtual int SkipOffTokenChannelsReverse(int i)
{
while (i >= 0 && ((IToken)_tokens[i]).Channel != _channel)
{
i--;
}
return i;
}
public override void Reset()
{
base.Reset();
_p = SkipOffTokenChannels(0);
}
protected override void Setup()
{
_p = 0;
_p = SkipOffTokenChannels(_p);
}
}
}
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