1 /* 2 * [The "BSD licence"] 3 * Copyright (c) 2005-2008 Terence Parr 4 * All rights reserved. 5 * 6 * Conversion to C#: 7 * Copyright (c) 2009 Sam Harwell 8 * All rights reserved. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. The name of the author may not be used to endorse or promote products 19 * derived from this software without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 22 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 23 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 24 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 25 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 26 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 27 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 28 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 29 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 30 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 31 */ 32 33 namespace Antlr.Runtime 34 { 35 using Antlr.Runtime.Misc; 36 using CLSCompliant = System.CLSCompliantAttribute; 37 using NotSupportedException = System.NotSupportedException; 38 using IndexOutOfRangeException = System.IndexOutOfRangeException; 39 40 /** A token stream that pulls tokens from the code source on-demand and 41 * without tracking a complete buffer of the tokens. This stream buffers 42 * the minimum number of tokens possible. It's the same as 43 * OnDemandTokenStream except that OnDemandTokenStream buffers all tokens. 44 * 45 * You can't use this stream if you pass whitespace or other off-channel 46 * tokens to the parser. The stream can't ignore off-channel tokens. 47 * 48 * You can only look backwards 1 token: LT(-1). 49 * 50 * Use this when you need to read from a socket or other infinite stream. 51 * 52 * @see BufferedTokenStream 53 * @see CommonTokenStream 54 */ 55 public class UnbufferedTokenStream : LookaheadStream<IToken>, ITokenStream, ITokenStreamInformation 56 { 57 [CLSCompliant(false)] 58 protected ITokenSource tokenSource; 59 protected int tokenIndex; // simple counter to set token index in tokens 60 61 /** Skip tokens on any channel but this one; this is how we skip whitespace... */ 62 protected int channel = TokenChannels.Default; 63 64 private readonly ListStack<IToken> _realTokens = new ListStack<IToken>() { null }; 65 UnbufferedTokenStream(ITokenSource tokenSource)66 public UnbufferedTokenStream(ITokenSource tokenSource) 67 { 68 this.tokenSource = tokenSource; 69 } 70 71 public ITokenSource TokenSource 72 { 73 get 74 { 75 return this.tokenSource; 76 } 77 } 78 79 public string SourceName 80 { 81 get 82 { 83 return TokenSource.SourceName; 84 } 85 } 86 87 #region ITokenStreamInformation Members 88 89 public IToken LastToken 90 { 91 get 92 { 93 return LB(1); 94 } 95 } 96 97 public IToken LastRealToken 98 { 99 get 100 { 101 return _realTokens.Peek(); 102 } 103 } 104 105 public int MaxLookBehind 106 { 107 get 108 { 109 return 1; 110 } 111 } 112 Mark()113 public override int Mark() 114 { 115 _realTokens.Push(_realTokens.Peek()); 116 return base.Mark(); 117 } 118 Release(int marker)119 public override void Release(int marker) 120 { 121 base.Release(marker); 122 _realTokens.Pop(); 123 } 124 Clear()125 public override void Clear() 126 { 127 _realTokens.Clear(); 128 _realTokens.Push(null); 129 } 130 Consume()131 public override void Consume() 132 { 133 base.Consume(); 134 if (PreviousElement != null && PreviousElement.Line > 0) 135 _realTokens[_realTokens.Count - 1] = PreviousElement; 136 } 137 138 #endregion 139 NextElement()140 public override IToken NextElement() 141 { 142 IToken t = this.tokenSource.NextToken(); 143 t.TokenIndex = this.tokenIndex++; 144 return t; 145 } 146 IsEndOfFile(IToken o)147 public override bool IsEndOfFile(IToken o) 148 { 149 return o.Type == CharStreamConstants.EndOfFile; 150 } 151 Get(int i)152 public IToken Get(int i) 153 { 154 throw new NotSupportedException("Absolute token indexes are meaningless in an unbuffered stream"); 155 } 156 LA(int i)157 public int LA(int i) 158 { 159 return LT(i).Type; 160 } 161 ToString(int start, int stop)162 public string ToString(int start, int stop) 163 { 164 return "n/a"; 165 } 166 ToString(IToken start, IToken stop)167 public string ToString(IToken start, IToken stop) 168 { 169 return "n/a"; 170 } 171 } 172 } 173