ITokenSource.cs revision 324c4644fee44b9898524c09511bd33c3f12e2df 
1/*
2[The "BSD licence"]
3Copyright (c) 2007-2008 Johannes Luber
4Copyright (c) 2005-2007 Kunle Odutola
5All rights reserved.
6
7Redistribution and use in source and binary forms, with or without
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163. The name of the author may not be used to endorse or promote products
17   derived from this software without specific prior WRITTEN permission.
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23THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
24IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
25OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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33*/
34
35
36namespace Antlr.Runtime
37{
38	using System;
39
40	/// <summary>
41	/// A source of tokens must provide a sequence of tokens via NextToken()
42	/// and also must reveal it's source of characters; CommonToken's text is
43	/// computed from a CharStream; it only store indices into the char stream.
44	///
45	/// Errors from the lexer are never passed to the parser.  Either you want
46	/// to keep going or you do not upon token recognition error.  If you do not
47	/// want to continue lexing then you do not want to continue parsing.  Just
48	/// throw an exception not under RecognitionException and Java will naturally
49	/// toss you all the way out of the recognizers.  If you want to continue
50	/// lexing then you should not throw an exception to the parser--it has already
51	/// requested a token.  Keep lexing until you get a valid one.  Just report
52	/// errors and keep going, looking for a valid token.
53	/// </summary>
54	public interface ITokenSource
55	{
56		/// <summary>
57		/// Returns a Token object from the input stream (usually a CharStream).
58		/// Does not fail/return upon lexing error; just keeps chewing on the
59		/// characters until it gets a good one; errors are not passed through
60		/// to the parser.
61		/// </summary>
62		IToken NextToken();
63
64		/// <summary>
65		/// Where are you getting tokens from? normally the implication will simply
66		/// ask lexers input stream.
67		/// </summary>
68		string SourceName {
69			get;
70		}
71	}
72}