xref: /external/antlr/antlr-3.4/runtime/CSharp2/Sources/Antlr3.Runtime/Antlr.Runtime/ITokenSource.cs

/*
[The "BSD licence"]
Copyright (c) 2007-2008 Johannes Luber
Copyright (c) 2005-2007 Kunle Odutola
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.
4. Unless explicitly state otherwise, any contribution intentionally
   submitted for inclusion in this work to the copyright owner or licensor
   shall be under the terms and conditions of this license, without any
   additional terms or conditions.

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,
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*/


namespace Antlr.Runtime
{
	using System;

	/// <summary>
	/// A source of tokens must provide a sequence of tokens via NextToken()
	/// and also must reveal it's source of characters; CommonToken's text is
	/// computed from a CharStream; it only store indices into the char stream.
	///
	/// Errors from the lexer are never passed to the parser.  Either you want
	/// to keep going or you do not upon token recognition error.  If you do not
	/// want to continue lexing then you do not want to continue parsing.  Just
	/// throw an exception not under RecognitionException and Java will naturally
	/// toss you all the way out of the recognizers.  If you want to continue
	/// lexing then you should not throw an exception to the parser--it has already
	/// requested a token.  Keep lexing until you get a valid one.  Just report
	/// errors and keep going, looking for a valid token.
	/// </summary>
	public interface ITokenSource
	{
		/// <summary>
		/// Returns a Token object from the input stream (usually a CharStream).
		/// Does not fail/return upon lexing error; just keeps chewing on the
		/// characters until it gets a good one; errors are not passed through
		/// to the parser.
		/// </summary>
		IToken NextToken();

		/// <summary>
		/// Where are you getting tokens from? normally the implication will simply
		/// ask lexers input stream.
		/// </summary>
		string SourceName {
			get;
		}
	}
}