/*
 * Bytecode Analysis Framework
 * Copyright (C) 2003,2004 University of Maryland
 * 
 * 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

package edu.umd.cs.findbugs.ba.type;

/**
 * Extended type codes used by StackAndLocalTypes and StackAndLocalTypeAnalysis
 * for typing locals and stack values used in Java bytecode.
 *
 * @author David Hovemeyer
 * @see TypeFrame
 * @see TypeAnalysis
 */
public interface ExtendedTypes {
	// FIXME: these values depend on those in org.apache.bcel.Constants.
	// They need to be distinct from all type codes defined there.
	// It would be nice if BCEL provided built-in functionality for
	// some or all of these.

	/**
	 * Special type code for the "Top" type in the lattice.
	 */
	public static final byte T_TOP = 17;

	/**
	 * Special type that represents the value store in
	 * local <i>n+1</i> when a long value is stored in
	 * local <i>n</i>.
	 */
	public static final byte T_LONG_EXTRA = 18;

	/**
	 * Special type that represents the value store in
	 * local <i>n+1</i> when a double value is stored in
	 * local <i>n</i>.
	 */
	public static final byte T_DOUBLE_EXTRA = 19;

	/**
	 * Special type code for the "Bottom" type in the lattice.
	 */
	public static final byte T_BOTTOM = 20;

	/**
	 * Special type code for the "Null" type.
	 * This is a type which is higher in the lattice than any object type,
	 * but lower than the overall Top type.  It represents the type
	 * of the null value, which may logically be merged with any
	 * object type without loss of information.
	 */
	public static final byte T_NULL = 21;

	/**
	 * Special type code for "Exception" object type,
	 * which is an instance of the ExceptionObjectType class.
	 * These instances maintain an ExceptionSet to keep track
	 * of possible exceptions that are feasible, and whether those
	 * exceptions are explicit or implicit.
	 */
	public static final byte T_EXCEPTION = 22;

	/**
	 * A Type code that is available for "user-defined" types.
	 * Any type code equal or greated than this one is guaranteed
	 * to be distinct from both standard and extended types.
	 */
	public static final byte T_AVAIL_TYPE = 100;
}

// vim:ts=4
