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 /** A source of tokens must provide a sequence of tokens via nextToken() 31 * and also must reveal it's source of characters; CommonToken's text is 32 * computed from a CharStream; it only store indices into the char stream. 33 * 34 * Errors from the lexer are never passed to the parser. Either you want 35 * to keep going or you do not upon token recognition error. If you do not 36 * want to continue lexing then you do not want to continue parsing. Just 37 * throw an exception not under RecognitionException and Java will naturally 38 * toss you all the way out of the recognizers. If you want to continue 39 * lexing then you should not throw an exception to the parser--it has already 40 * requested a token. Keep lexing until you get a valid one. Just report 41 * errors and keep going, looking for a valid token. 42 */ 43 public interface TokenSource { 44 /** Return a Token object from your input stream (usually a CharStream). 45 * Do not fail/return upon lexing error; keep chewing on the characters 46 * until you get a good one; errors are not passed through to the parser. 47 */ 48 public Token nextToken(); 49 50 /** Where are you getting tokens from? normally the implication will simply 51 * ask lexers input stream. 52 */ 53 public String getSourceName(); 54 } 55
