1 /* 2 * [The "BSD license"] 3 * Copyright (c) 2010 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.analysis; 29 30 import org.antlr.misc.IntSet; 31 import org.antlr.misc.IntervalSet; 32 import org.antlr.tool.Grammar; 33 34 /** An LL(1) lookahead set; contains a set of token types and a "hasEOF" 35 * condition when the set contains EOF. Since EOF is -1 everywhere and -1 36 * cannot be stored in my BitSet, I set a condition here. There may be other 37 * reasons in the future to abstract a LookaheadSet over a raw BitSet. 38 */ 39 public class LookaheadSet { 40 public IntervalSet tokenTypeSet; 41 LookaheadSet()42 public LookaheadSet() { 43 tokenTypeSet = new IntervalSet(); 44 } 45 LookaheadSet(IntSet s)46 public LookaheadSet(IntSet s) { 47 this(); 48 tokenTypeSet.addAll(s); 49 } 50 LookaheadSet(int atom)51 public LookaheadSet(int atom) { 52 tokenTypeSet = IntervalSet.of(atom); 53 } 54 LookaheadSet(LookaheadSet other)55 public LookaheadSet(LookaheadSet other) { 56 this(); 57 this.tokenTypeSet.addAll(other.tokenTypeSet); 58 } 59 orInPlace(LookaheadSet other)60 public void orInPlace(LookaheadSet other) { 61 this.tokenTypeSet.addAll(other.tokenTypeSet); 62 } 63 or(LookaheadSet other)64 public LookaheadSet or(LookaheadSet other) { 65 return new LookaheadSet(tokenTypeSet.or(other.tokenTypeSet)); 66 } 67 subtract(LookaheadSet other)68 public LookaheadSet subtract(LookaheadSet other) { 69 return new LookaheadSet(this.tokenTypeSet.subtract(other.tokenTypeSet)); 70 } 71 member(int a)72 public boolean member(int a) { 73 return tokenTypeSet.member(a); 74 } 75 intersection(LookaheadSet s)76 public LookaheadSet intersection(LookaheadSet s) { 77 IntSet i = this.tokenTypeSet.and(s.tokenTypeSet); 78 LookaheadSet intersection = new LookaheadSet(i); 79 return intersection; 80 } 81 isNil()82 public boolean isNil() { 83 return tokenTypeSet.isNil(); 84 } 85 remove(int a)86 public void remove(int a) { 87 tokenTypeSet = tokenTypeSet.subtract(IntervalSet.of(a)); 88 } 89 90 @Override hashCode()91 public int hashCode() { 92 return tokenTypeSet.hashCode(); 93 } 94 95 @Override equals(Object other)96 public boolean equals(Object other) { 97 return tokenTypeSet.equals(((LookaheadSet)other).tokenTypeSet); 98 } 99 toString(Grammar g)100 public String toString(Grammar g) { 101 if ( tokenTypeSet==null ) { 102 return ""; 103 } 104 String r = tokenTypeSet.toString(g); 105 return r; 106 } 107 108 @Override toString()109 public String toString() { 110 return toString(null); 111 } 112 } 113