/*
 * 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 represents colection of local variables in a method. This
 * attribute is contained in the <em>Code</em> attribute.
 * 
 * @version $Id: LocalVariableTable.java 386056 2006-03-15 11:31:56Z tcurdt $
 * @author <A HREF="mailto:m.dahm@gmx.de">M. Dahm</A>
 * @see Code
 * @see LocalVariable
 */
public class LocalVariableTable extends Attribute {

	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;
	private int local_variable_table_length; // Table of local
	private LocalVariable[] local_variable_table; // variables

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

	/**
	 * @param name_index
	 *            Index in constant pool to `LocalVariableTable'
	 * @param length
	 *            Content length in bytes
	 * @param local_variable_table
	 *            Table of local variables
	 * @param constant_pool
	 *            Array of constants
	 */
	public LocalVariableTable(int name_index, int length,
			LocalVariable[] local_variable_table, ConstantPool constant_pool) {
		super(Constants.ATTR_LOCAL_VARIABLE_TABLE, name_index, length,
				constant_pool);
		setLocalVariableTable(local_variable_table);
	}

	/**
	 * Construct object from file stream.
	 * 
	 * @param name_index
	 *            Index in constant pool
	 * @param length
	 *            Content length in bytes
	 * @param file
	 *            Input stream
	 * @param constant_pool
	 *            Array of constants
	 * @throws IOException
	 */
	LocalVariableTable(int name_index, int length, DataInputStream file,
			ConstantPool constant_pool) throws IOException {
		this(name_index, length, (LocalVariable[]) null, constant_pool);
		local_variable_table_length = (file.readUnsignedShort());
		local_variable_table = new LocalVariable[local_variable_table_length];
		for (int i = 0; i < local_variable_table_length; i++) {
			local_variable_table[i] = new LocalVariable(file, constant_pool);
		}
	}

	/**
	 * 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.visitLocalVariableTable(this);
	}

	/**
	 * Dump local variable table attribute to file stream in binary format.
	 * 
	 * @param file
	 *            Output file stream
	 * @throws IOException
	 */
	@Override
	public final void dump(DataOutputStream file) throws IOException {
		super.dump(file);
		file.writeShort(local_variable_table_length);
		for (int i = 0; i < local_variable_table_length; i++) {
			local_variable_table[i].dump(file);
		}
	}

	/**
	 * @return Array of local variables of method.
	 */
	public final LocalVariable[] getLocalVariableTable() {
		return local_variable_table;
	}

	/**
	 * @return first matching variable using index
	 * 
	 * @param index
	 *            the variable slot
	 * 
	 * @return the first LocalVariable that matches the slot or null if not
	 *         found
	 * 
	 */
	public final LocalVariable getLocalVariable(int index) {
		for (int i = 0; i < local_variable_table_length; i++) {
			if (local_variable_table[i].getIndex() == index) {
				return local_variable_table[i];
			}
		}
		return null;
	}

	/**
	 * @return matching variable using index when variable is used at supplied
	 *         pc
	 * 
	 * @param index
	 *            the variable slot
	 * @param pc
	 *            the current pc that this variable is alive
	 * 
	 * @return the LocalVariable that matches or null if not found
	 */
	public final LocalVariable getLocalVariable(int index, int pc) {
		for (int i = 0; i < local_variable_table_length; i++) {
			if (local_variable_table[i].getIndex() == index) {
				int start_pc = local_variable_table[i].getStartPC();
				int end_pc = start_pc + local_variable_table[i].getLength();
				if ((pc >= start_pc) && (pc < end_pc)) {
					return local_variable_table[i];
				}
			}
		}
		return null;
	}

	public final void setLocalVariableTable(LocalVariable[] local_variable_table) {
		this.local_variable_table = local_variable_table;
		local_variable_table_length = (local_variable_table == null) ? 0
				: local_variable_table.length;
	}

	/**
	 * @return String representation.
	 */
	@Override
	public final String toString() {
		StringBuffer buf = new StringBuffer("");
		for (int i = 0; i < local_variable_table_length; i++) {
			buf.append(local_variable_table[i].toString());
			if (i < local_variable_table_length - 1) {
				buf.append('\n');
			}
		}
		return buf.toString();
	}

	/**
	 * @return deep copy of this attribute
	 */
	@Override
	public Attribute copy(ConstantPool _constant_pool) {
		LocalVariableTable c = (LocalVariableTable) clone();
		c.local_variable_table = new LocalVariable[local_variable_table_length];
		for (int i = 0; i < local_variable_table_length; i++) {
			c.local_variable_table[i] = local_variable_table[i].copy();
		}
		c.constant_pool = _constant_pool;
		return c;
	}

	public final int getTableLength() {
		return local_variable_table_length;
	}
}
