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