tool/src/main/java/org/antlr/analysis/PredicateLabel.java

/*
 * [The "BSD license"]
 *  Copyright (c) 2010 Terence Parr
 *  All rights reserved.
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions
 *  are met:
 *  1. Redistributions of source code must retain the above copyright
 *      notice, this list of conditions and the following disclaimer.
 *  2. Redistributions in binary form must reproduce the above copyright
 *      notice, this list of conditions and the following disclaimer in the
 *      documentation and/or other materials provided with the distribution.
 *  3. The name of the author may not be used to endorse or promote products
 *      derived from this software without specific prior written permission.
 *
 *  THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 *  IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 *  OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 *  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 *  INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 *  NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 *  DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 *  THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 *  THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.antlr.analysis;

import org.antlr.tool.Grammar;
import org.antlr.tool.GrammarAST;

public class PredicateLabel extends Label {
	/** A tree of semantic predicates from the grammar AST if label==SEMPRED.
	 *  In the NFA, labels will always be exactly one predicate, but the DFA
	 *  may have to combine a bunch of them as it collects predicates from
	 *  multiple NFA configurations into a single DFA state.
	 */
	protected SemanticContext semanticContext;
	
	/** Make a semantic predicate label */
	public PredicateLabel(GrammarAST predicateASTNode) {
		super(SEMPRED);
		this.semanticContext = new SemanticContext.Predicate(predicateASTNode);
	}

	/** Make a semantic predicates label */
	public PredicateLabel(SemanticContext semCtx) {
		super(SEMPRED);
		this.semanticContext = semCtx;
	}

	@Override
	public int hashCode() {
		return semanticContext.hashCode();
	}

	@Override
	public boolean equals(Object o) {
		if ( o==null ) {
			return false;
		}
		if ( this == o ) {
			return true; // equals if same object
		}
		if ( !(o instanceof PredicateLabel) ) {
			return false;
		}
		return semanticContext.equals(((PredicateLabel)o).semanticContext);
	}

	@Override
	public boolean isSemanticPredicate() {
		return true;
	}

	@Override
	public SemanticContext getSemanticContext() {
		return semanticContext;
	}

	@Override
	public String toString() {
		return "{"+semanticContext+"}?";
	}

	@Override
	public String toString(Grammar g) {
		return toString();
	}
}