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.commons.compress.harmony.unpack200.bytecode;
018
019import java.io.DataOutputStream;
020import java.io.IOException;
021import java.util.Arrays;
022import java.util.List;
023
024import org.apache.commons.compress.harmony.pack200.Pack200Exception;
025
026/**
027 * Abstract superclass for attributes that have some part encoded with a BCI renumbering
028 */
029public abstract class BCIRenumberedAttribute extends Attribute {
030
031    protected boolean renumbered;
032
033    public BCIRenumberedAttribute(final CPUTF8 attributeName) {
034        super(attributeName);
035    }
036
037    @Override
038    protected abstract int getLength();
039
040    protected abstract int[] getStartPCs();
041
042    /*
043     * (non-Javadoc)
044     *
045     * @see org.apache.commons.compress.harmony.unpack200.bytecode.Attribute#hasBCIRenumbering()
046     */
047    @Override
048    public boolean hasBCIRenumbering() {
049        return true;
050    }
051
052    /**
053     * In Pack200, line number tables are BCI renumbered. This method takes the byteCodeOffsets (which is a List of Integers specifying the offset in the byte
054     * code array of each instruction) and updates the start_pcs so that it points to the instruction index itself, not the BCI renumbering of the instruction.
055     *
056     * @param byteCodeOffsets List of Integer offsets of the byte code array
057     * @throws Pack200Exception Thrown from a subclass.
058     */
059    public void renumber(final List<Integer> byteCodeOffsets) throws Pack200Exception {
060        if (renumbered) {
061            throw new Error("Trying to renumber a line number table that has already been renumbered");
062        }
063        renumbered = true;
064        final int[] startPCs = getStartPCs();
065        Arrays.setAll(startPCs, i -> byteCodeOffsets.get(startPCs[i]).intValue());
066    }
067
068    @Override
069    public abstract String toString();
070
071    @Override
072    protected abstract void writeBody(DataOutputStream dos) throws IOException;
073
074}