/*
 *  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.harmony.unpack200.bytecode.forms;

import org.apache.harmony.pack200.Pack200Exception;
import org.apache.harmony.unpack200.SegmentConstantPool;
import org.apache.harmony.unpack200.bytecode.ByteCode;
import org.apache.harmony.unpack200.bytecode.ClassFileEntry;
import org.apache.harmony.unpack200.bytecode.OperandManager;

/**
 * Abstract class of all ByteCodeForms which add a nested entry from the
 * globalConstantPool.
 */
public abstract class ReferenceForm extends ByteCodeForm {

    public ReferenceForm(int opcode, String name, int[] rewrite) {
        super(opcode, name, rewrite);
    }

    protected abstract int getPoolID();

    protected abstract int getOffset(OperandManager operandManager);

    protected void setNestedEntries(ByteCode byteCode,
            OperandManager operandManager, int offset) throws Pack200Exception {
        final SegmentConstantPool globalPool = operandManager
                .globalConstantPool();
        ClassFileEntry[] nested = null;
        nested = new ClassFileEntry[] { globalPool.getConstantPoolEntry(
                getPoolID(), offset) };
        if(nested[0] == null) {
            throw new NullPointerException("Null nested entries are not allowed");
        }
        byteCode.setNested(nested);
        byteCode.setNestedPositions(new int[][] { { 0, 2 } });
    }

    /*
     * (non-Javadoc)
     *
     * @see org.apache.harmony.unpack200.bytecode.forms.ByteCodeForm#setByteCodeOperands(org.apache.harmony.unpack200.bytecode.ByteCode,
     *      org.apache.harmony.unpack200.bytecode.OperandTable,
     *      org.apache.harmony.unpack200.Segment)
     */
    public void setByteCodeOperands(ByteCode byteCode,
            OperandManager operandManager, int codeLength) {
        final int offset = getOffset(operandManager);
        try {
            setNestedEntries(byteCode, operandManager, offset);
        } catch (final Pack200Exception ex) {
            throw new Error("Got a pack200 exception. What to do?");
        }
    }
}
