xref: /external/antlr/antlr-3.4/runtime/ActionScript/project/src/org/antlr/runtime/TokenStream.as

/*
 [The "BSD licence"]
 Copyright (c) 2005-2006 Terence Parr
 All rights reserved.

 Redistribution and use in source and binary forms, with or without
 modification, are permitted provided that the following conditions
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 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.
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*/
package org.antlr.runtime {

	/** A stream of tokens accessing tokens from a TokenSource */
	public interface TokenStream extends IntStream {
	    /** Get Token at current input pointer + i ahead where i=1 is next Token.
		 *  i<0 indicates tokens in the past.  So -1 is previous token and -2 is
		 *  two tokens ago. LT(0) is undefined.  For i>=n, return Token.EOFToken.
		 *  Return null for LT(0) and any index that results in an absolute address
		 *  that is negative.
		 */
	    function LT(k:int):Token;

		/** Get a token at an absolute index i; 0..n-1.  This is really only
		 *  needed for profiling and debugging and token stream rewriting.
		 *  If you don't want to buffer up tokens, then this method makes no
		 *  sense for you.  Naturally you can't use the rewrite stream feature.
		 *  I believe DebugTokenStream can easily be altered to not use
		 *  this method, removing the dependency.
		 */
		function getToken(i:int):Token;

		/** Where is this stream pulling tokens from?  This is not the name, but
		 *  the object that provides Token objects.
		 */
		function get tokenSource():TokenSource;

		/** Return the text of all tokens from start to stop, inclusive.
		 *  If the stream does not buffer all the tokens then it can just
		 *  return "" or null;  Users should not access $ruleLabel.text in
		 *  an action of course in that case.
		 */
		function toStringWithRange(start:int, stop:int):String;

		/** Because the user is not required to use a token with an index stored
		 *  in it, we must provide a means for two token objects themselves to
		 *  indicate the start/end location.  Most often this will just delegate
		 *  to the other toString(int,int).  This is also parallel with
		 *  the TreeNodeStream.toString(Object,Object).
		 */
		function toStringWithTokenRange(start:Token, stop:Token):String;
	}

}