/**
 * All files in the distribution of BLOAT (Bytecode Level Optimization and
 * Analysis tool for Java(tm)) are Copyright 1997-2001 by the Purdue
 * Research Foundation of Purdue University.  All rights reserved.
 * 
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 */

package EDU.purdue.cs.bloat.editor;

/**
 * LocalVariable represents a local variable index operand to various
 * instructions.
 * 
 * @author Nate Nystrom (<a
 *         href="mailto:nystrom@cs.purdue.edu">nystrom@cs.purdue.edu</a>)
 */
public class LocalVariable {
	private String name;

	private Type type;

	private int index;

	/**
	 * Constructor.
	 * 
	 * @param index
	 *            The index of the local variable in the method's local variable
	 *            array.
	 */
	public LocalVariable(final int index) {
		this.name = null;
		this.type = null;
		this.index = index;
	}

	/**
	 * Constructor.
	 * 
	 * @param name
	 *            The name of the local variable.
	 * @param type
	 *            The descriptor (or index into the constant pool) representing
	 *            the variable type.
	 * @param index
	 *            The index of the local variable in the method's local variable
	 *            array.
	 */
	public LocalVariable(final String name, final Type type, final int index) {
		this.name = name;
		this.type = type;
		this.index = index;
	}

	/**
	 * Hash the local variable.
	 * 
	 * A stricter hashing than using the index will break Hashtable lookups
	 * since a variable could have a name assigned to it after its first use.
	 * 
	 * @return The hash code.
	 */
	public int hashCode() {
		return index;
	}

	/**
	 * Check if an object is equal to this variable.
	 * 
	 * A stricter comparison than comparing indices will break Hashtable lookups
	 * since a variable could have a name assigned to it after its first use.
	 * 
	 * @param obj
	 *            The object to compare against.
	 * @return true if equal, false if not.
	 */
	public boolean equals(final Object obj) {
		return (obj != null) && (obj instanceof LocalVariable)
				&& (((LocalVariable) obj).index == index);
	}

	/**
	 * Get the name of the local variable.
	 * 
	 * @return The name of the local variable.
	 */
	public String name() {
		return name;
	}

	/**
	 * Get the type of the local variable.
	 * 
	 * @return The type of the local variable.
	 */
	public Type type() {
		return type;
	}

	/**
	 * Get the index into the local variable array.
	 * 
	 * @return The index into the local variable array.
	 */
	public int index() {
		return index;
	}

	/**
	 * Convert the variable to a string.
	 * 
	 * @return A string representation of the variable.
	 */
	public String toString() {
		if (name == null) {
			return "Local$" + index;
		}

		return name + "$" + index;
	}
}