    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.forms;
    020
    021import java.util.Objects;
    022
    023import org.apache.commons.compress.harmony.pack200.Pack200Exception;
    024import org.apache.commons.compress.harmony.unpack200.SegmentConstantPool;
    025import org.apache.commons.compress.harmony.unpack200.bytecode.ByteCode;
    026import org.apache.commons.compress.harmony.unpack200.bytecode.ClassFileEntry;
    027import org.apache.commons.compress.harmony.unpack200.bytecode.OperandManager;
    028
    029/**
    030 * Abstract class of all ByteCodeForms which add a nested entry from the globalConstantPool.
    031 */
    032public abstract class ReferenceForm extends ByteCodeForm {
    033
    034    /**
    035     * Constructs a new instance with the specified opcode, name, operandType and rewrite.
    036     *
    037     * @param opcode  index corresponding to the opcode's value.
    038     * @param name    String printable name of the opcode.
    039     * @param rewrite Operand positions (which will later be rewritten in ByteCodes) are indicated by -1.
    040     */
    041    public ReferenceForm(final int opcode, final String name, final int[] rewrite) {
    042        super(opcode, name, rewrite);
    043    }
    044
    045    protected abstract int getOffset(OperandManager operandManager);
    046
    047    protected abstract int getPoolID();
    048
    049    /*
    050     * (non-Javadoc)
    051     *
    052     * @see org.apache.commons.compress.harmony.unpack200.bytecode.forms.ByteCodeForm#setByteCodeOperands(org.apache.commons.
    053     * compress.harmony.unpack200.bytecode.ByteCode, org.apache.commons.compress.harmony.unpack200.bytecode.OperandTable,
    054     * org.apache.commons.compress.harmony.unpack200.Segment)
    055     */
    056    @Override
    057    public void setByteCodeOperands(final ByteCode byteCode, final OperandManager operandManager, final int codeLength) throws Pack200Exception {
    058        final int offset = getOffset(operandManager);
    059        try {
    060            setNestedEntries(byteCode, operandManager, offset);
    061        } catch (final Pack200Exception ex) {
    062            throw new Error("Got a pack200 exception. What to do?");
    063        }
    064    }
    065
    066    /**
    067     * Sets the nested entries.
    068     *
    069     * @param byteCode byte codes.
    070     * @param operandManager Operand manager.
    071     * @param offset offset.
    072     * @throws Pack200Exception if support for a type is not supported or the offset not in the range [0, {@link Integer#MAX_VALUE}].
    073     */
    074    protected void setNestedEntries(final ByteCode byteCode, final OperandManager operandManager, final int offset) throws Pack200Exception {
    075        final SegmentConstantPool globalPool = operandManager.globalConstantPool();
    076        final ClassFileEntry[] nested = { globalPool.getConstantPoolEntry(getPoolID(), offset) };
    077        Objects.requireNonNull(nested[0], "Null nested entries are not allowed");
    078        byteCode.setNested(nested);
    079        byteCode.setNestedPositions(new int[][] { { 0, 2 } });
    080    }
    081}