src/org/apache/xalan/xsltc/compiler/AlternativePattern.java

/*
 * @(#)$Id$
 *
 * The Apache Software License, Version 1.1
 *
 *
 * Copyright (c) 2001-2003 The Apache Software Foundation.  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 end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
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 * 4. The names "Xalan" and "Apache Software Foundation" must
 *    not be used to endorse or promote products derived from this
 *    software without prior written permission. For written
 *    permission, please contact apache@apache.org.
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 * 5. Products derived from this software may not be called "Apache",
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 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
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 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation and was
 * originally based on software copyright (c) 2001, Sun
 * Microsystems., http://www.sun.com.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 * @author Jacek Ambroziak
 * @author Santiago Pericas-Geertsen
 *
 */

package org.apache.xalan.xsltc.compiler;

import org.apache.xalan.xsltc.compiler.util.Type;
import org.apache.bcel.generic.*;
import org.apache.xalan.xsltc.compiler.util.*;

final class AlternativePattern extends Pattern {
    private final Pattern _left;
    private final Pattern _right;
		
    /**
     * Construct an alternative pattern. The method <code>setParent</code>
     * should not be called in this case.
     */
    public AlternativePattern(Pattern left, Pattern right) {
	_left = left;
	_right = right;
    }
		
    public void setParser(Parser parser) {
	super.setParser(parser);
	_left.setParser(parser);
	_right.setParser(parser);
    }
    
    public Pattern getLeft() {
	return _left;
    }

    public Pattern getRight() {
	return _right;
    }

    /**
     * The type of an '|' is not really defined, hence null is returned.
     */
    public Type typeCheck(SymbolTable stable) throws TypeCheckError {
	_left.typeCheck(stable);
	_right.typeCheck(stable);
	return null;
    }

    public double getPriority() {
	double left = _left.getPriority();
	double right = _right.getPriority();
	
	if (left < right)
	    return(left);
	else
	    return(right);
    }

    public String toString() {
	return "alternative(" + _left + ", " + _right + ')';
    }

    public void translate(ClassGenerator classGen, MethodGenerator methodGen) {
	final InstructionList il = methodGen.getInstructionList();

	_left.translate(classGen, methodGen);
	final InstructionHandle gotot = il.append(new GOTO(null));
	il.append(methodGen.loadContextNode());
	_right.translate(classGen, methodGen);

	_left._trueList.backPatch(gotot);
	_left._falseList.backPatch(gotot.getNext());

	_trueList.append(_right._trueList.add(gotot));
	_falseList.append(_right._falseList);
    }
}