    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 */
    017package org.apache.bcel.generic;
    018
    019import org.apache.bcel.Const;
    020
    021/**
    022 * Returnaddress, the type JSR or JSR_W instructions push upon the stack.
    023 *
    024 * see vmspec2 �3.3.3
    025 */
    026public class ReturnaddressType extends Type {
    027
    028    public static final ReturnaddressType NO_TARGET = new ReturnaddressType();
    029    private InstructionHandle returnTarget;
    030
    031    /**
    032     * A Returnaddress [that doesn't know where to return to].
    033     */
    034    private ReturnaddressType() {
    035        super(Const.T_ADDRESS, "<return address>");
    036    }
    037
    038    /**
    039     * Creates a ReturnaddressType object with a target.
    040     */
    041    public ReturnaddressType(final InstructionHandle returnTarget) {
    042        super(Const.T_ADDRESS, "<return address targeting " + returnTarget + ">");
    043        this.returnTarget = returnTarget;
    044    }
    045
    046    /**
    047     * Returns if the two Returnaddresses refer to the same target.
    048     */
    049    @Override
    050    public boolean equals(final Object rat) {
    051        if (!(rat instanceof ReturnaddressType)) {
    052            return false;
    053        }
    054        final ReturnaddressType that = (ReturnaddressType) rat;
    055        if (this.returnTarget == null || that.returnTarget == null) {
    056            return that.returnTarget == this.returnTarget;
    057        }
    058        return that.returnTarget.equals(this.returnTarget);
    059    }
    060
    061    /**
    062     * @return the target of this ReturnaddressType
    063     */
    064    public InstructionHandle getTarget() {
    065        return returnTarget;
    066    }
    067
    068    /**
    069     * @return a hash code value for the object.
    070     */
    071    @Override
    072    public int hashCode() {
    073        if (returnTarget == null) {
    074            return 0;
    075        }
    076        return returnTarget.hashCode();
    077    }
    078}