ChairsReloaded/src/org/apache/bcel/classfile/ConstantValue.java

/*
 * Copyright  2000-2004 The Apache Software Foundation
 *
 *  Licensed 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.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import org.apache.bcel.Constants;

/**
 * This class is derived from <em>Attribute</em> and represents a constant
 * value, i.e., a default value for initializing a class field. This class is
 * instantiated by the <em>Attribute.readAttribute()</em> method.
 * 
 * @version $Id: ConstantValue.java 386056 2006-03-15 11:31:56Z tcurdt $
 * @author <A HREF="mailto:m.dahm@gmx.de">M. Dahm</A>
 * @see Attribute
 */
public final class ConstantValue extends Attribute {

	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;
	private int constantvalue_index;

	/**
	 * Initialize from another object. Note that both objects use the same
	 * references (shallow copy). Use clone() for a physical copy.
	 */
	public ConstantValue(ConstantValue c) {
		this(c.getNameIndex(), c.getLength(), c.getConstantValueIndex(), c
				.getConstantPool());
	}

	/**
	 * Construct object from file stream.
	 * 
	 * @param name_index
	 *            Name index in constant pool
	 * @param length
	 *            Content length in bytes
	 * @param file
	 *            Input stream
	 * @param constant_pool
	 *            Array of constants
	 * @throws IOException
	 */
	ConstantValue(int name_index, int length, DataInputStream file,
			ConstantPool constant_pool) throws IOException {
		this(name_index, length, file.readUnsignedShort(), constant_pool);
	}

	/**
	 * @param name_index
	 *            Name index in constant pool
	 * @param length
	 *            Content length in bytes
	 * @param constantvalue_index
	 *            Index in constant pool
	 * @param constant_pool
	 *            Array of constants
	 */
	public ConstantValue(int name_index, int length, int constantvalue_index,
			ConstantPool constant_pool) {
		super(Constants.ATTR_CONSTANT_VALUE, name_index, length, constant_pool);
		this.constantvalue_index = constantvalue_index;
	}

	/**
	 * Called by objects that are traversing the nodes of the tree implicitely
	 * defined by the contents of a Java class. I.e., the hierarchy of methods,
	 * fields, attributes, etc. spawns a tree of objects.
	 * 
	 * @param v
	 *            Visitor object
	 */
	@Override
	public void accept(Visitor v) {
		v.visitConstantValue(this);
	}

	/**
	 * Dump constant value attribute to file stream on binary format.
	 * 
	 * @param file
	 *            Output file stream
	 * @throws IOException
	 */
	@Override
	public final void dump(DataOutputStream file) throws IOException {
		super.dump(file);
		file.writeShort(constantvalue_index);
	}

	/**
	 * @return Index in constant pool of constant value.
	 */
	public final int getConstantValueIndex() {
		return constantvalue_index;
	}

	/**
	 * @param constantvalue_index
	 *            the index info the constant pool of this constant value
	 */
	public final void setConstantValueIndex(int constantvalue_index) {
		this.constantvalue_index = constantvalue_index;
	}

	/**
	 * @return String representation of constant value.
	 */
	@Override
	public final String toString() {
		Constant c = constant_pool.getConstant(constantvalue_index);
		String buf;
		int i;
		// Print constant to string depending on its type
		switch (c.getTag()) {
		case Constants.CONSTANT_Long:
			buf = "" + ((ConstantLong) c).getBytes();
			break;
		case Constants.CONSTANT_Float:
			buf = "" + ((ConstantFloat) c).getBytes();
			break;
		case Constants.CONSTANT_Double:
			buf = "" + ((ConstantDouble) c).getBytes();
			break;
		case Constants.CONSTANT_Integer:
			buf = "" + ((ConstantInteger) c).getBytes();
			break;
		case Constants.CONSTANT_String:
			i = ((ConstantString) c).getStringIndex();
			c = constant_pool.getConstant(i, Constants.CONSTANT_Utf8);
			buf = "\"" + Utility.convertString(((ConstantUtf8) c).getBytes())
					+ "\"";
			break;
		default:
			throw new IllegalStateException("Type of ConstValue invalid: " + c);
		}
		return buf;
	}

	/**
	 * @return deep copy of this attribute
	 */
	@Override
	public Attribute copy(ConstantPool _constant_pool) {
		ConstantValue c = (ConstantValue) clone();
		c.constant_pool = _constant_pool;
		return c;
	}
}