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;
022import org.apache.bcel.ExceptionConst;
023
024/**
025 * Super class for the xRETURN family of instructions.
026 */
027public abstract class ReturnInstruction extends Instruction implements ExceptionThrower, TypedInstruction, StackConsumer {
028
029    /**
030     * Empty constructor needed for Instruction.readInstruction. Not to be used otherwise.
031     */
032    ReturnInstruction() {
033    }
034
035    /**
036     * Constructs a ReturnInstruction.
037     *
038     * @param opcode of instruction.
039     */
040    protected ReturnInstruction(final short opcode) {
041        super(opcode, (short) 1);
042    }
043
044    @Override
045    public Class<?>[] getExceptions() {
046        return new Class[] {ExceptionConst.ILLEGAL_MONITOR_STATE};
047    }
048
049    /**
050     * Gets the type of the returned value.
051     *
052     * @return The type.
053     */
054    public Type getType() {
055        final short opcode = super.getOpcode();
056        switch (opcode) {
057        case Const.IRETURN:
058            return Type.INT;
059        case Const.LRETURN:
060            return Type.LONG;
061        case Const.FRETURN:
062            return Type.FLOAT;
063        case Const.DRETURN:
064            return Type.DOUBLE;
065        case Const.ARETURN:
066            return Type.OBJECT;
067        case Const.RETURN:
068            return Type.VOID;
069        default: // Never reached
070            throw new ClassGenException("Unknown type " + opcode);
071        }
072    }
073
074    /**
075     * @return type associated with the instruction.
076     */
077    @Override
078    public Type getType(final ConstantPoolGen cp) {
079        return getType();
080    }
081}