1 /* 2 [The "BSD license"] 3 Copyright (c) 2005-2009 Terence Parr 4 All rights reserved. 5 6 Redistribution and use in source and binary forms, with or without 7 modification, are permitted provided that the following conditions 8 are met: 9 1. Redistributions of source code must retain the above copyright 10 notice, this list of conditions and the following disclaimer. 11 2. Redistributions in binary form must reproduce the above copyright 12 notice, this list of conditions and the following disclaimer in the 13 documentation and/or other materials provided with the distribution. 14 3. The name of the author may not be used to endorse or promote products 15 derived from this software without specific prior written permission. 16 17 THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 18 IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 19 OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 20 IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 21 INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 22 NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 26 THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 */ 28 package org.antlr.runtime; 29 30 import java.util.List; 31 32 /** A stream of tokens accessing tokens from a TokenSource */ 33 public interface TokenStream extends IntStream { 34 /** Get Token at current input pointer + i ahead where i=1 is next Token. 35 * i<0 indicates tokens in the past. So -1 is previous token and -2 is 36 * two tokens ago. LT(0) is undefined. For i>=n, return Token.EOFToken. 37 * Return null for LT(0) and any index that results in an absolute address 38 * that is negative. 39 */ 40 public Token LT(int k); 41 42 /** How far ahead has the stream been asked to look? The return 43 * value is a valid index from 0..n-1. 44 */ 45 int range(); 46 47 /** Get a token at an absolute index i; 0..n-1. This is really only 48 * needed for profiling and debugging and token stream rewriting. 49 * If you don't want to buffer up tokens, then this method makes no 50 * sense for you. Naturally you can't use the rewrite stream feature. 51 * I believe DebugTokenStream can easily be altered to not use 52 * this method, removing the dependency. 53 */ 54 public Token get(int i); 55 56 /** Where is this stream pulling tokens from? This is not the name, but 57 * the object that provides Token objects. 58 */ 59 public TokenSource getTokenSource(); 60 61 /** Return the text of all tokens from start to stop, inclusive. 62 * If the stream does not buffer all the tokens then it can just 63 * return "" or null; Users should not access $ruleLabel.text in 64 * an action of course in that case. 65 */ 66 public String toString(int start, int stop); 67 68 /** Because the user is not required to use a token with an index stored 69 * in it, we must provide a means for two token objects themselves to 70 * indicate the start/end location. Most often this will just delegate 71 * to the other toString(int,int). This is also parallel with 72 * the TreeNodeStream.toString(Object,Object). 73 */ 74 public String toString(Token start, Token stop); 75 } 76
