/*
 * 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 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.
 *
 * @version $Id$
 * @see     LineNumber
 * @see     MethodGen
 */
public class LineNumberGen implements InstructionTargeter, Cloneable {

    private InstructionHandle ih;
    private int src_line;


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


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


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


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


    public void setInstruction( final InstructionHandle ih ) { // TODO could be package-protected?
        if (ih == null) {
            throw new NullPointerException("InstructionHandle may not be null");
        }
        BranchInstruction.notifyTarget(this.ih, ih, this);
        this.ih = ih;
    }


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


    public InstructionHandle getInstruction() {
        return ih;
    }


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


    public int getSourceLine() {
        return src_line;
    }
}
