001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *   https://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing,
013 * software distributed under the License is distributed on an
014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 * KIND, either express or implied.  See the License for the
016 * specific language governing permissions and limitations
017 * under the License.
018 */
019package org.apache.bcel.generic;
020
021import org.apache.bcel.Const;
022
023/**
024 * Returnaddress, the type JSR or JSR_W instructions push upon the stack.
025 *
026 * see vmspec2 �3.3.3
027 */
028public class ReturnaddressType extends Type {
029
030    public static final ReturnaddressType NO_TARGET = new ReturnaddressType();
031    private InstructionHandle returnTarget;
032
033    /**
034     * A Returnaddress [that doesn't know where to return to].
035     */
036    private ReturnaddressType() {
037        super(Const.T_ADDRESS, "<return address>");
038    }
039
040    /**
041     * Creates a ReturnaddressType object with a target.
042     */
043    public ReturnaddressType(final InstructionHandle returnTarget) {
044        super(Const.T_ADDRESS, "<return address targeting " + returnTarget + ">");
045        this.returnTarget = returnTarget;
046    }
047
048    /**
049     * Returns if the two Returnaddresses refer to the same target.
050     */
051    @Override
052    public boolean equals(final Object rat) {
053        if (!(rat instanceof ReturnaddressType)) {
054            return false;
055        }
056        final ReturnaddressType that = (ReturnaddressType) rat;
057        if (this.returnTarget == null || that.returnTarget == null) {
058            return that.returnTarget == this.returnTarget;
059        }
060        return that.returnTarget.equals(this.returnTarget);
061    }
062
063    /**
064     * @return the target of this ReturnaddressType
065     */
066    public InstructionHandle getTarget() {
067        return returnTarget;
068    }
069
070    /**
071     * @return a hash code value for the object.
072     */
073    @Override
074    public int hashCode() {
075        if (returnTarget == null) {
076            return 0;
077        }
078        return returnTarget.hashCode();
079    }
080}