/*

 * reserved comment block

 * DO NOT REMOVE OR ALTER!

 */

/*

 * Licensed to the Apache Software Foundation (ASF) under one or more

 * contributor license agreements.  See the NOTICE file distributed with

 * this work for additional information regarding copyright ownership.

 * The ASF licenses this file to You under the Apache License, Version 2.0

 * (the "License"); you may not use this file except in compliance with

 * the License.  You may obtain a copy of the License at

 *

 *      http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

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package com.sun.org.apache.xalan.internal.xsltc.compiler;

import com.sun.org.apache.bcel.internal.generic.GOTO;

import com.sun.org.apache.bcel.internal.generic.InstructionHandle;

import com.sun.org.apache.bcel.internal.generic.InstructionList;

import com.sun.org.apache.xalan.internal.xsltc.compiler.util.ClassGenerator;

import com.sun.org.apache.xalan.internal.xsltc.compiler.util.MethodGenerator;

import com.sun.org.apache.xalan.internal.xsltc.compiler.util.Type;

import com.sun.org.apache.xalan.internal.xsltc.compiler.util.TypeCheckError;

/**

 * @author Jacek Ambroziak

 * @author Santiago Pericas-Geertsen

 */

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);

    }

}