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The ANTLR 4 grammar compiler.
There is a newer version: 4.9.0
/*
 * [The "BSD license"]
 *  Copyright (c) 2012 Terence Parr
 *  Copyright (c) 2012 Sam Harwell
 *  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
 *  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 *  THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package org.antlr.v4.codegen.model;

import org.antlr.v4.codegen.ActionTranslator;
import org.antlr.v4.codegen.CodeGenerator;
import org.antlr.v4.codegen.OutputModelFactory;
import org.antlr.v4.codegen.model.chunk.ActionChunk;
import org.antlr.v4.runtime.atn.AbstractPredicateTransition;
import org.antlr.v4.runtime.misc.NotNull;
import org.antlr.v4.tool.ast.ActionAST;
import org.antlr.v4.tool.ast.GrammarAST;

import java.util.List;

/** */
public class SemPred extends Action {
	/**
	 * The user-specified terminal option {@code fail}, if it was used and the
	 * value is a string literal. For example:
	 *
	 * 
	 * {@code {pred}?}
	 */
	public String msg;
	/**
	 * The predicate string with { and }? stripped from the ends.
	 */
	public String predicate;

	/**
	 * The translated chunks of the user-specified terminal option {@code fail},
	 * if it was used and the value is an action. For example:
	 *
	 * 
	 * {@code {pred}?}
	 */
	@ModelElement public List failChunks;

	public SemPred(OutputModelFactory factory, @NotNull ActionAST ast) {
		super(factory,ast);

		assert ast.atnState != null
			&& ast.atnState.getNumberOfTransitions() == 1
			&& ast.atnState.transition(0) instanceof AbstractPredicateTransition;

		GrammarAST failNode = ast.getOptionAST("fail");
		predicate = ast.getText();
		if (predicate.startsWith("{") && predicate.endsWith("}?")) {
			predicate = predicate.substring(1, predicate.length() - 2);
		}
		predicate = factory.getTarget().getTargetStringLiteralFromString(predicate);

		if ( failNode==null ) return;

		if ( failNode instanceof ActionAST ) {
			ActionAST failActionNode = (ActionAST)failNode;
			RuleFunction rf = factory.getCurrentRuleFunction();
			failChunks = ActionTranslator.translateAction(factory, rf,
														  failActionNode.token,
														  failActionNode);
		}
		else {
			msg = factory.getTarget().getTargetStringLiteralFromANTLRStringLiteral(factory.getGenerator(),
																		  failNode.getText(),
																		  true);
		}
	}
}