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.commons.compress.harmony.unpack200.bytecode;
020
021import java.io.DataOutputStream;
022import java.io.IOException;
023import java.util.Arrays;
024import java.util.List;
025
026import org.apache.commons.compress.harmony.pack200.Pack200Exception;
027
028/**
029 * Abstract superclass for attributes that have some part encoded with Byte Code Injection (BCI) renumbering.
030 */
031public abstract class BCIRenumberedAttribute extends Attribute {
032
033    /**
034     * Whether renumbering has occurred.
035     */
036    protected boolean renumbered;
037
038    /**
039     * Constructs a new instance for an attribute name.
040     *
041     * @param attributeName an attribute name.
042     */
043    public BCIRenumberedAttribute(final CPUTF8 attributeName) {
044        super(attributeName);
045    }
046
047    @Override
048    protected abstract int getLength();
049
050    /**
051     * Gets the array of indices for the start of line numbers.
052     *
053     * @return the array of indices for the start of line numbers.
054     */
055    protected abstract int[] getStartPCs();
056
057    /*
058     * (non-Javadoc)
059     *
060     * @see org.apache.commons.compress.harmony.unpack200.bytecode.Attribute#hasBCIRenumbering()
061     */
062    @Override
063    public boolean hasBCIRenumbering() {
064        return true;
065    }
066
067    /**
068     * 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
069     * 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.
070     *
071     * @param byteCodeOffsets List of Integer offsets of the byte code array.
072     * @throws Pack200Exception Thrown from a subclass.
073     */
074    public void renumber(final List<Integer> byteCodeOffsets) throws Pack200Exception {
075        if (renumbered) {
076            throw new Error("Trying to renumber a line number table that has already been renumbered");
077        }
078        renumbered = true;
079        final int[] startPCs = getStartPCs();
080        Arrays.setAll(startPCs, i -> byteCodeOffsets.get(startPCs[i]).intValue());
081    }
082
083    @Override
084    public abstract String toString();
085
086    @Override
087    protected abstract void writeBody(DataOutputStream dos) throws IOException;
088
089}