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      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.tool.Grammar;
     31 import org.antlr.tool.GrammarAST;
     32 
     33 public class PredicateLabel extends Label {
     34 	/** A tree of semantic predicates from the grammar AST if label==SEMPRED.
     35 	 *  In the NFA, labels will always be exactly one predicate, but the DFA
     36 	 *  may have to combine a bunch of them as it collects predicates from
     37 	 *  multiple NFA configurations into a single DFA state.
     38 	 */
     39 	protected SemanticContext semanticContext;
     40 
     41 	/** Make a semantic predicate label */
     42 	public PredicateLabel(GrammarAST predicateASTNode) {
     43 		super(SEMPRED);
     44 		this.semanticContext = new SemanticContext.Predicate(predicateASTNode);
     45 	}
     46 
     47 	/** Make a semantic predicates label */
     48 	public PredicateLabel(SemanticContext semCtx) {
     49 		super(SEMPRED);
     50 		this.semanticContext = semCtx;
     51 	}
     52 
     53 	public int hashCode() {
     54 		return semanticContext.hashCode();
     55 	}
     56 
     57 	public boolean equals(Object o) {
     58 		if ( o==null ) {
     59 			return false;
     60 		}
     61 		if ( this == o ) {
     62 			return true; // equals if same object
     63 		}
     64 		if ( !(o instanceof PredicateLabel) ) {
     65 			return false;
     66 		}
     67 		return semanticContext.equals(((PredicateLabel)o).semanticContext);
     68 	}
     69 
     70 	public boolean isSemanticPredicate() {
     71 		return true;
     72 	}
     73 
     74 	public SemanticContext getSemanticContext() {
     75 		return semanticContext;
     76 	}
     77 
     78 	public String toString() {
     79 		return "{"+semanticContext+"}?";
     80 	}
     81 
     82 	public String toString(Grammar g) {
     83 		return toString();
     84 	}
     85 }
     86