commons-bcel-master/src/main/java/org/apache/bcel/classfile/ConstantCP.java
/*
 * 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.classfile;

import java.io.DataInput;
import java.io.DataOutputStream;
import java.io.IOException;

import org.apache.bcel.Const;

/**
 * Abstract super class for Fieldref, Methodref, InterfaceMethodref and InvokeDynamic constants.
 *
 * @see ConstantFieldref
 * @see ConstantMethodref
 * @see ConstantInterfaceMethodref
 * @see ConstantInvokeDynamic
 */
public abstract class ConstantCP extends Constant {

    /**
     * References to the constants containing the class and the field signature
     */
    // Note that this field is used to store the
    // bootstrap_method_attr_index of a ConstantInvokeDynamic.
    /**
     * @deprecated (since 6.0) will be made private; do not access directly, use getter/setter
     */
    @java.lang.Deprecated
    protected int class_index; // TODO make private (has getter & setter)
    // This field has the same meaning for all subclasses.

    /**
     * @deprecated (since 6.0) will be made private; do not access directly, use getter/setter
     */
    @java.lang.Deprecated
    protected int name_and_type_index; // TODO make private (has getter & setter)

    /**
     * Initialize instance from file data.
     *
     * @param tag Constant type tag
     * @param file Input stream
     * @throws IOException if an I/O error occurs.
     */
    ConstantCP(final byte tag, final DataInput file) throws IOException {
        this(tag, file.readUnsignedShort(), file.readUnsignedShort());
    }

    /**
     * @param classIndex Reference to the class containing the field
     * @param nameAndTypeIndex and the field signature
     */
    protected ConstantCP(final byte tag, final int classIndex, final int nameAndTypeIndex) {
        super(tag);
        this.class_index = classIndex;
        this.name_and_type_index = nameAndTypeIndex;
    }

    /**
     * Initialize from another object.
     *
     * @param c Source to copy.
     */
    public ConstantCP(final ConstantCP c) {
        this(c.getTag(), c.getClassIndex(), c.getNameAndTypeIndex());
    }

    /**
     * Dump constant field reference to file stream in binary format.
     *
     * @param file Output file stream
     * @throws IOException if an I/O error occurs.
     */
    @Override
    public final void dump(final DataOutputStream file) throws IOException {
        file.writeByte(super.getTag());
        file.writeShort(class_index);
        file.writeShort(name_and_type_index);
    }

    /**
     * @return Class this field belongs to.
     */
    public String getClass(final ConstantPool cp) {
        return cp.constantToString(class_index, Const.CONSTANT_Class);
    }

    /**
     * @return Reference (index) to class this constant refers to.
     */
    public final int getClassIndex() {
        return class_index;
    }

    /**
     * @return Reference (index) to signature of the field.
     */
    public final int getNameAndTypeIndex() {
        return name_and_type_index;
    }

    /**
     * @param classIndex points to Constant_class
     */
    public final void setClassIndex(final int classIndex) {
        this.class_index = classIndex;
    }

    /**
     * @param nameAndTypeIndex points to Constant_NameAndType
     */
    public final void setNameAndTypeIndex(final int nameAndTypeIndex) {
        this.name_and_type_index = nameAndTypeIndex;
    }

    /**
     * @return String representation.
     *
     *         not final as ConstantInvokeDynamic needs to modify
     */
    @Override
    public String toString() {
        return super.toString() + "(class_index = " + class_index + ", name_and_type_index = " + name_and_type_index + ")";
    }
}
