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package org.antlr.runtime;

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

	
How far ahead has the stream been asked to look?  The return
 value is a valid index from 0..n-1.
/** How far ahead has the stream been asked to look?  The return
	 *  value is a valid index from 0..n-1.
	 */
	int range();
	
	
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.
/** 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.
	 */
	public Token get(int i);

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

	
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.
/** 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.
	 */
	public String toString(int start, int stop);

	
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).
/** 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).
	 */
	public String toString(Token start, Token stop);
}