| /* |
| * [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++; |
| Sync(_p); |
| while (_tokens[_p].Channel != _channel) { |
| _p++; |
| Sync(_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; |
| } |
| |
| protected override void Setup() { |
| _p = 0; |
| Sync(0); |
| int i = 0; |
| while (_tokens[i].Channel != _channel) { |
| i++; |
| Sync(i); |
| } |
| _p = i; |
| } |
| } |
| } |