commons-bcel-master/src/main/java/org/apache/bcel/generic/LineNumberGen.java
/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */
package org.apache.bcel.generic;

import java.util.Objects;

import org.apache.bcel.classfile.LineNumber;

/**
 * This class represents a line number within a method, i.e., give an instruction a line number corresponding to the
 * source code line.
 *
 * @see LineNumber
 * @see MethodGen
 */
public class LineNumberGen implements InstructionTargeter, Cloneable {

    static final LineNumberGen[] EMPTY_ARRAY = {};

    private InstructionHandle ih;
    private int srcLine;

    /**
     * Create a line number.
     *
     * @param ih instruction handle to reference
     */
    public LineNumberGen(final InstructionHandle ih, final int srcLine) {
        setInstruction(ih);
        setSourceLine(srcLine);
    }

    @Override
    public Object clone() {
        try {
            return super.clone();
        } catch (final CloneNotSupportedException e) {
            throw new UnsupportedOperationException("Clone Not Supported", e); // never happens
        }
    }

    /**
     * @return true, if ih is target of this line number
     */
    @Override
    public boolean containsTarget(final InstructionHandle ih) {
        return this.ih == ih;
    }

    public InstructionHandle getInstruction() {
        return ih;
    }

    /**
     * Get LineNumber attribute.
     *
     * This relies on that the instruction list has already been dumped to byte code or that the 'setPositions' methods
     * has been called for the instruction list.
     */
    public LineNumber getLineNumber() {
        return new LineNumber(ih.getPosition(), srcLine);
    }

    public int getSourceLine() {
        return srcLine;
    }

    public void setInstruction(final InstructionHandle instructionHandle) { // TODO could be package-protected?
        Objects.requireNonNull(instructionHandle, "instructionHandle");
        BranchInstruction.notifyTarget(this.ih, instructionHandle, this);
        this.ih = instructionHandle;
    }

    public void setSourceLine(final int srcLine) { // TODO could be package-protected?
        this.srcLine = srcLine;
    }

    /**
     * @param oldIh old target
     * @param newIh new target
     */
    @Override
    public void updateTarget(final InstructionHandle oldIh, final InstructionHandle newIh) {
        if (oldIh != ih) {
            throw new ClassGenException("Not targeting " + oldIh + ", but " + ih + "}");
        }
        setInstruction(newIh);
    }
}
