    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 java.io.DataOutputStream;
    022import java.io.IOException;
    023
    024/**
    025 * JSR - Jump to subroutine
    026 */
    027public class JSR extends JsrInstruction implements VariableLengthInstruction {
    028
    029    /**
    030     * Empty constructor needed for Instruction.readInstruction. Not to be used otherwise.
    031     */
    032    JSR() {
    033    }
    034
    035    public JSR(final InstructionHandle target) {
    036        super(org.apache.bcel.Const.JSR, target);
    037    }
    038
    039    /**
    040     * Call corresponding visitor method(s). The order is: Call visitor methods of implemented interfaces first, then call
    041     * methods according to the class hierarchy in descending order, that is, the most specific visitXXX() call comes last.
    042     *
    043     * @param v Visitor object.
    044     */
    045    @Override
    046    public void accept(final Visitor v) {
    047        v.visitStackProducer(this);
    048        v.visitVariableLengthInstruction(this);
    049        v.visitBranchInstruction(this);
    050        v.visitJsrInstruction(this);
    051        v.visitJSR(this);
    052    }
    053
    054    /**
    055     * Dumps instruction as byte code to stream out.
    056     *
    057     * @param out Output stream.
    058     */
    059    @Override
    060    public void dump(final DataOutputStream out) throws IOException {
    061        super.setIndex(getTargetOffset());
    062        if (super.getOpcode() == org.apache.bcel.Const.JSR) {
    063            super.dump(out);
    064        } else { // JSR_W
    065            super.setIndex(getTargetOffset());
    066            out.writeByte(super.getOpcode());
    067            out.writeInt(super.getIndex());
    068        }
    069    }
    070
    071    @Override
    072    protected int updatePosition(final int offset, final int maxOffset) {
    073        final int i = getTargetOffset(); // Depending on old position value
    074        setPosition(getPosition() + offset); // Position may be shifted by preceding expansions
    075        if (Math.abs(i) >= Short.MAX_VALUE - maxOffset) { // to large for short (estimate)
    076            super.setOpcode(org.apache.bcel.Const.JSR_W);
    077            final short oldLength = (short) super.getLength();
    078            super.setLength(5);
    079            return super.getLength() - oldLength;
    080        }
    081        return 0;
    082    }
    083}