/*****************************************************************************
 *                                                                           *
 *  This file is part of the BeanShell Java Scripting distribution.          *
 *  Documentation and updates may be found at http://www.beanshell.org/      *
 *                                                                           *
 *  Sun Public License Notice:                                               *
 *                                                                           *
 *  The contents of this file are subject to the Sun Public License Version  *
 *  1.0 (the "License"); you may not use this file except in compliance with *
 *  the License. A copy of the License is available at http://www.sun.com    * 
 *                                                                           *
 *  The Original Code is BeanShell. The Initial Developer of the Original    *
 *  Code is Pat Niemeyer. Portions created by Pat Niemeyer are Copyright     *
 *  (C) 2000.  All Rights Reserved.                                          *
 *                                                                           *
 *  GNU Public License Notice:                                               *
 *                                                                           *
 *  Alternatively, the contents of this file may be used under the terms of  *
 *  the GNU Lesser General Public License (the "LGPL"), in which case the    *
 *  provisions of LGPL are applicable instead of those above. If you wish to *
 *  allow use of your version of this file only under the  terms of the LGPL *
 *  and not to allow others to use your version of this file under the SPL,  *
 *  indicate your decision by deleting the provisions above and replace      *
 *  them with the notice and other provisions required by the LGPL.  If you  *
 *  do not delete the provisions above, a recipient may use your version of  *
 *  this file under either the SPL or the LGPL.                              *
 *                                                                           *
 *  Patrick Niemeyer (pat@pat.net)                                           *
 *  Author of Learning Java, O'Reilly & Associates                           *
 *  http://www.pat.net/~pat/                                                 *
 *                                                                           *
 *****************************************************************************/


package bsh;

import java.util.Hashtable;

/**
    Wrapper for primitive types in Bsh.  This is package public because it 
	is used in the implementation of some bsh commands.

    See the note in LHS.java about wrapping objects.
*/
/*
	Note: this class is final because we may test == Primitive.class in places.
	If we need to change that search for those tests.
*/
public final class Primitive implements ParserConstants, java.io.Serializable
{
	static Hashtable primitiveToWrapper = new Hashtable();
	static Hashtable wrapperToPrimitive = new Hashtable();
	static {
		primitiveToWrapper.put( Boolean.TYPE, Boolean.class );
		primitiveToWrapper.put( Byte.TYPE, Byte.class );
		primitiveToWrapper.put( Short.TYPE, Short.class );
		primitiveToWrapper.put( Character.TYPE, Character.class );
		primitiveToWrapper.put( Integer.TYPE, Integer.class );
		primitiveToWrapper.put( Long.TYPE, Long.class );
		primitiveToWrapper.put( Float.TYPE, Float.class );
		primitiveToWrapper.put( Double.TYPE, Double.class );
		wrapperToPrimitive.put( Boolean.class, Boolean.TYPE );
		wrapperToPrimitive.put( Byte.class, Byte.TYPE );
		wrapperToPrimitive.put( Short.class, Short.TYPE );
		wrapperToPrimitive.put( Character.class, Character.TYPE );
		wrapperToPrimitive.put( Integer.class, Integer.TYPE );
		wrapperToPrimitive.put( Long.class, Long.TYPE );
		wrapperToPrimitive.put( Float.class, Float.TYPE );
		wrapperToPrimitive.put( Double.class, Double.TYPE );
	}

    /** The primitive value stored in its java.lang wrapper class */
    private Object value;

    private static class Special implements java.io.Serializable
    {
        private Special() { }

        public static final Special NULL_VALUE = new Special();
        public static final Special VOID_TYPE = new Special();
    }

    /*
        NULL means "no value".
        This ia a placeholder for primitive null value.
    */
    public static final Primitive NULL = new Primitive(Special.NULL_VALUE);

    /**
        VOID means "no type".
        Strictly speaking, this makes no sense here.  But for practical
        reasons we'll consider the lack of a type to be a special value.
    */
    public static final Primitive VOID = new Primitive(Special.VOID_TYPE);

    // private to prevent invocation with param that isn't a primitive-wrapper
    public Primitive( Object value )
    {
        if ( value == null )
            throw new InterpreterError(
				"Use Primitve.NULL instead of Primitive(null)");

		if ( value != Special.NULL_VALUE 
			&& value != Special.VOID_TYPE &&
			!isWrapperType( value.getClass() ) 
		)
            throw new InterpreterError( "Not a wrapper type: "+value);

        this.value = value;
    }

    public Primitive(boolean value) { this(new Boolean(value)); }
    public Primitive(byte value) { this(new Byte(value)); }
    public Primitive(short value) { this(new Short(value)); }
    public Primitive(char value) { this(new Character(value)); }
    public Primitive(int value) { this(new Integer(value)); }
    public Primitive(long value) { this(new Long(value)); }
    public Primitive(float value) { this(new Float(value)); }
    public Primitive(double value) { this(new Double(value)); }

	/**
    	Return the primitive value stored in its java.lang wrapper class 
	*/
    public Object getValue()
    {
        if ( value == Special.NULL_VALUE )
            return null;
        else 
		if ( value == Special.VOID_TYPE )
                throw new InterpreterError("attempt to unwrap void type");
        else
            return value;
    }

    public String toString()
    {
        if(value == Special.NULL_VALUE)
            return "null";
        else if(value == Special.VOID_TYPE)
            return "void";
        else
            return value.toString();
    }

	/**
		Get the corresponding Java primitive TYPE class for this Primitive.
		@return the primitive TYPE class type of the value or Void.TYPE for
		Primitive.VOID or null value for type of Primitive.NULL
	*/
    public Class getType()
    {
		if ( this == Primitive.VOID )
			return Void.TYPE;

		// NULL return null as type... we currently use null type to indicate 
		// loose typing throughout bsh.
		if ( this == Primitive.NULL )
			return null;

		return unboxType( value.getClass() );
    }

	/**
		Perform a binary operation on two Primitives or wrapper types.
		If both original args were Primitives return a Primitive result
		else it was mixed (wrapper/primitive) return the wrapper type.
		The exception is for boolean operations where we will return the 
		primitive type eithe way.
	*/
    public static Object binaryOperation(
		Object obj1, Object obj2, int kind)
        throws UtilEvalError
    {
		// special primitive types
        if ( obj1 == NULL || obj2 == NULL )
            throw new UtilEvalError(
				"Null value or 'null' literal in binary operation");
        if ( obj1 == VOID || obj2 == VOID )
            throw new UtilEvalError(
			"Undefined variable, class, or 'void' literal in binary operation");

		// keep track of the original types
		Class lhsOrgType = obj1.getClass();
		Class rhsOrgType = obj2.getClass();

		// Unwrap primitives
        if ( obj1 instanceof Primitive )
            obj1 = ((Primitive)obj1).getValue();
        if ( obj2 instanceof Primitive )
            obj2 = ((Primitive)obj2).getValue();

        Object[] operands = promotePrimitives(obj1, obj2);
        Object lhs = operands[0];
        Object rhs = operands[1];

        if(lhs.getClass() != rhs.getClass())
            throw new UtilEvalError("Type mismatch in operator.  " 
			+ lhs.getClass() + " cannot be used with " + rhs.getClass() );

		Object result;
		try {
			result = binaryOperationImpl( lhs, rhs, kind );
		} catch ( ArithmeticException e ) {
			throw new UtilTargetError( "Arithemetic Exception in binary op", e);
		}

		// If both original args were Primitives return a Primitive result
		// else it was mixed (wrapper/primitive) return the wrapper type
		// Exception is for boolean result, return the primitive
		if ( (lhsOrgType == Primitive.class && rhsOrgType == Primitive.class)
			|| result instanceof Boolean
		)
			return new Primitive( result );
		else
			return result;
    }

    static Object binaryOperationImpl( Object lhs, Object rhs, int kind )
        throws UtilEvalError
	{
        if(lhs instanceof Boolean)
            return booleanBinaryOperation((Boolean)lhs, (Boolean)rhs, kind);
        else if(lhs instanceof Integer)
            return intBinaryOperation( (Integer)lhs, (Integer)rhs, kind );
        else if(lhs instanceof Long)
            return longBinaryOperation((Long)lhs, (Long)rhs, kind);
        else if(lhs instanceof Float)
            return floatBinaryOperation((Float)lhs, (Float)rhs, kind);
        else if(lhs instanceof Double)
            return doubleBinaryOperation( (Double)lhs, (Double)rhs, kind);
        else
            throw new UtilEvalError("Invalid types in binary operator" );
	}

    static Boolean booleanBinaryOperation(Boolean B1, Boolean B2, int kind)
        throws UtilEvalError
    {
        boolean lhs = B1.booleanValue();
        boolean rhs = B2.booleanValue();

        switch(kind)
        {
            case EQ:
                return new Boolean(lhs == rhs);

            case NE:
                return new Boolean(lhs != rhs);

            case BOOL_OR:
            case BOOL_ORX:
                return new Boolean( lhs || rhs );

            case BOOL_AND:
            case BOOL_ANDX:
                return new Boolean( lhs && rhs );

            default:
                throw new InterpreterError("unimplemented binary operator");
        }
    }

    // returns Object covering both Long and Boolean return types
    static Object longBinaryOperation(Long L1, Long L2, int kind)
    {
        long lhs = L1.longValue();
        long rhs = L2.longValue();

        switch(kind)
        {
            // boolean
            case LT:
            case LTX:
                return new Boolean(lhs < rhs);

            case GT:
            case GTX:
                return new Boolean(lhs > rhs);

            case EQ:
                return new Boolean(lhs == rhs);

            case LE:
            case LEX:
                return new Boolean(lhs <= rhs);

            case GE:
            case GEX:
                return new Boolean(lhs >= rhs);

            case NE:
                return new Boolean(lhs != rhs);

            // arithmetic
            case PLUS:
                return new Long(lhs + rhs);

            case MINUS:
                return new Long(lhs - rhs);

            case STAR:
                return new Long(lhs * rhs);

            case SLASH:
                return new Long(lhs / rhs);

            case MOD:
                return new Long(lhs % rhs);

            // bitwise
            case LSHIFT:
            case LSHIFTX:
                return new Long(lhs << rhs);

            case RSIGNEDSHIFT:
            case RSIGNEDSHIFTX:
                return new Long(lhs >> rhs);

            case RUNSIGNEDSHIFT:
            case RUNSIGNEDSHIFTX:
                return new Long(lhs >>> rhs);

            case BIT_AND:
            case BIT_ANDX:
                return new Long(lhs & rhs);

            case BIT_OR:
            case BIT_ORX:
                return new Long(lhs | rhs);

            case XOR:
                return new Long(lhs ^ rhs);

            default:
                throw new InterpreterError(
					"Unimplemented binary long operator");
        }
    }

    // returns Object covering both Integer and Boolean return types
    static Object intBinaryOperation(Integer I1, Integer I2, int kind)
    {
        int lhs = I1.intValue();
        int rhs = I2.intValue();

        switch(kind)
        {
            // boolean
            case LT:
            case LTX:
                return new Boolean(lhs < rhs);

            case GT:
            case GTX:
                return new Boolean(lhs > rhs);

            case EQ:
                return new Boolean(lhs == rhs);

            case LE:
            case LEX:
                return new Boolean(lhs <= rhs);

            case GE:
            case GEX:
                return new Boolean(lhs >= rhs);

            case NE:
                return new Boolean(lhs != rhs);

            // arithmetic
            case PLUS:
                return new Integer(lhs + rhs);

            case MINUS:
                return new Integer(lhs - rhs);

            case STAR:
                return new Integer(lhs * rhs);

            case SLASH:
                return new Integer(lhs / rhs);

            case MOD:
                return new Integer(lhs % rhs);

            // bitwise
            case LSHIFT:
            case LSHIFTX:
                return new Integer(lhs << rhs);

            case RSIGNEDSHIFT:
            case RSIGNEDSHIFTX:
                return new Integer(lhs >> rhs);

            case RUNSIGNEDSHIFT:
            case RUNSIGNEDSHIFTX:
                return new Integer(lhs >>> rhs);

            case BIT_AND:
            case BIT_ANDX:
                return new Integer(lhs & rhs);

            case BIT_OR:
            case BIT_ORX:
                return new Integer(lhs | rhs);

            case XOR:
                return new Integer(lhs ^ rhs);

            default:
                throw new InterpreterError(
					"Unimplemented binary integer operator");
        }
    }

    // returns Object covering both Double and Boolean return types
    static Object doubleBinaryOperation(Double D1, Double D2, int kind)
        throws UtilEvalError
    {
        double lhs = D1.doubleValue();
        double rhs = D2.doubleValue();

        switch(kind)
        {
            // boolean
            case LT:
            case LTX:
                return new Boolean(lhs < rhs);

            case GT:
            case GTX:
                return new Boolean(lhs > rhs);

            case EQ:
                return new Boolean(lhs == rhs);

            case LE:
            case LEX:
                return new Boolean(lhs <= rhs);

            case GE:
            case GEX:
                return new Boolean(lhs >= rhs);

            case NE:
                return new Boolean(lhs != rhs);

            // arithmetic
            case PLUS:
                return new Double(lhs + rhs);

            case MINUS:
                return new Double(lhs - rhs);

            case STAR:
                return new Double(lhs * rhs);

            case SLASH:
                return new Double(lhs / rhs);

            case MOD:
                return new Double(lhs % rhs);

            // can't shift floating-point values
            case LSHIFT:
            case LSHIFTX:
            case RSIGNEDSHIFT:
            case RSIGNEDSHIFTX:
            case RUNSIGNEDSHIFT:
            case RUNSIGNEDSHIFTX:
                throw new UtilEvalError("Can't shift doubles");

            default:
                throw new InterpreterError(
					"Unimplemented binary double operator");
        }
    }
    // returns Object covering both Long and Boolean return types
    static Object floatBinaryOperation(Float F1, Float F2, int kind)
        throws UtilEvalError
    {
        float lhs = F1.floatValue();
        float rhs = F2.floatValue();

        switch(kind)
        {
            // boolean
            case LT:
            case LTX:
                return new Boolean(lhs < rhs);

            case GT:
            case GTX:
                return new Boolean(lhs > rhs);

            case EQ:
                return new Boolean(lhs == rhs);

            case LE:
            case LEX:
                return new Boolean(lhs <= rhs);

            case GE:
            case GEX:
                return new Boolean(lhs >= rhs);

            case NE:
                return new Boolean(lhs != rhs);

            // arithmetic
            case PLUS:
                return new Float(lhs + rhs);

            case MINUS:
                return new Float(lhs - rhs);

            case STAR:
                return new Float(lhs * rhs);

            case SLASH:
                return new Float(lhs / rhs);

            case MOD:
                return new Float(lhs % rhs);

            // can't shift floats
            case LSHIFT:
            case LSHIFTX:
            case RSIGNEDSHIFT:
            case RSIGNEDSHIFTX:
            case RUNSIGNEDSHIFT:
            case RUNSIGNEDSHIFTX:
                throw new UtilEvalError("Can't shift floats ");

            default:
                throw new InterpreterError(
					"Unimplemented binary float operator");
        }
    }

	/**
		Promote primitive wrapper type to to Integer wrapper type
	*/
    static Object promoteToInteger(Object wrapper )
    {
        if(wrapper instanceof Character)
            return new Integer(((Character)wrapper).charValue());
        else if((wrapper instanceof Byte) || (wrapper instanceof Short))
            return new Integer(((Number)wrapper).intValue());

        return wrapper;
    }

	/**
		Promote the pair of primitives to the maximum type of the two.
		e.g. [int,long]->[long,long]
	*/
    static Object[] promotePrimitives(Object lhs, Object rhs)
    {
        lhs = promoteToInteger(lhs);
        rhs = promoteToInteger(rhs);

        if((lhs instanceof Number) && (rhs instanceof Number))
        {
            Number lnum = (Number)lhs;
            Number rnum = (Number)rhs;

            boolean b;

            if((b = (lnum instanceof Double)) || (rnum instanceof Double))
            {
                if(b)
                    rhs = new Double(rnum.doubleValue());
                else
                    lhs = new Double(lnum.doubleValue());
            }
            else if((b = (lnum instanceof Float)) || (rnum instanceof Float))
            {
                if(b)
                    rhs = new Float(rnum.floatValue());
                else
                    lhs = new Float(lnum.floatValue());
            }
            else if((b = (lnum instanceof Long)) || (rnum instanceof Long))
            {
                if(b)
                    rhs = new Long(rnum.longValue());
                else
                    lhs = new Long(lnum.longValue());
            }
        }

        return new Object[] { lhs, rhs };
    }

    public static Primitive unaryOperation(Primitive val, int kind)
        throws UtilEvalError
    {
        if (val == NULL)
            throw new UtilEvalError(
				"illegal use of null object or 'null' literal");
        if (val == VOID)
            throw new UtilEvalError(
				"illegal use of undefined object or 'void' literal");

        Class operandType = val.getType();
        Object operand = promoteToInteger(val.getValue());

        if ( operand instanceof Boolean )
            return new Primitive(booleanUnaryOperation((Boolean)operand, kind));
        else if(operand instanceof Integer)
        {
            int result = intUnaryOperation((Integer)operand, kind);

            // ++ and -- must be cast back the original type
            if(kind == INCR || kind == DECR)
            {
                if(operandType == Byte.TYPE)
                    return new Primitive((byte)result);
                if(operandType == Short.TYPE)
                    return new Primitive((short)result);
                if(operandType == Character.TYPE)
                    return new Primitive((char)result);
            }

            return new Primitive(result);
        }
        else if(operand instanceof Long)
            return new Primitive(longUnaryOperation((Long)operand, kind));
        else if(operand instanceof Float)
            return new Primitive(floatUnaryOperation((Float)operand, kind));
        else if(operand instanceof Double)
            return new Primitive(doubleUnaryOperation((Double)operand, kind));
        else
            throw new InterpreterError(
				"An error occurred.  Please call technical support.");
    }

    static boolean booleanUnaryOperation(Boolean B, int kind) 
		throws UtilEvalError
    {
        boolean operand = B.booleanValue();
        switch(kind)
        {
            case BANG:
                return !operand;
            default:
                throw new UtilEvalError("Operator inappropriate for boolean");
        }
    }

    static int intUnaryOperation(Integer I, int kind)
    {
        int operand = I.intValue();

        switch(kind)
        {
            case PLUS:
                return operand;
            case MINUS:
                return -operand;
            case TILDE:
                return ~operand;
            case INCR:
                return operand + 1;
            case DECR:
                return operand - 1;
            default:
                throw new InterpreterError("bad integer unaryOperation");
        }
    }

    static long longUnaryOperation(Long L, int kind)
    {
        long operand = L.longValue();

        switch(kind)
        {
            case PLUS:
                return operand;
            case MINUS:
                return -operand;
            case TILDE:
                return ~operand;
            case INCR:
                return operand + 1;
            case DECR:
                return operand - 1;
            default:
                throw new InterpreterError("bad long unaryOperation");
        }
    }

    static float floatUnaryOperation(Float F, int kind)
    {
        float operand = F.floatValue();

        switch(kind)
        {
            case PLUS:
                return operand;
            case MINUS:
                return -operand;
            default:
                throw new InterpreterError("bad float unaryOperation");
        }
    }

    static double doubleUnaryOperation(Double D, int kind)
    {
        double operand = D.doubleValue();

        switch(kind)
        {
            case PLUS:
                return operand;
            case MINUS:
                return -operand;
            default:
                throw new InterpreterError("bad double unaryOperation");
        }
    }

    public int intValue() throws UtilEvalError
    {
        if(value instanceof Number)
            return((Number)value).intValue();
        else
            throw new UtilEvalError("Primitive not a number");
    }

    public boolean booleanValue() throws UtilEvalError
    {
        if(value instanceof Boolean)
            return((Boolean)value).booleanValue();
        else
            throw new UtilEvalError("Primitive not a boolean");
    }

	/**
		Determine if this primitive is a numeric type.
		i.e. not boolean, null, or void (but including char)
	*/
	public boolean isNumber() {
		return ( !(value instanceof Boolean) 
			&& !(this == NULL) && !(this == VOID) );
	}

    public Number numberValue() throws UtilEvalError
    {
		Object value = this.value;

		// Promote character to Number type for these purposes
		if (value instanceof Character)
			value = new Integer(((Character)value).charValue());

        if (value instanceof Number)
            return (Number)value;
        else
            throw new UtilEvalError("Primitive not a number");
    }

	/**
		Primitives compare equal with other Primitives containing an equal
		wrapped value.
	*/
	public boolean equals( Object obj ) 
	{
		if ( obj instanceof Primitive )
			return ((Primitive)obj).value.equals( this.value );
		else
			return false;
	}

	/**
		The hash of the Primitive is tied to the hash of the wrapped value but
		shifted so that they are not the same.
	*/
	public int hashCode() 
	{
		return this.value.hashCode() * 21; // arbitrary
	}

	/**
		Unwrap primitive values and map voids to nulls.
		Non Primitive types remain unchanged.

		@param obj object type which may be bsh.Primitive
		@return corresponding "normal" Java type, "unwrapping" 
			any bsh.Primitive types to their wrapper types.
	*/
	public static Object unwrap( Object obj ) 
	{
        // map voids to nulls for the outside world
        if (obj == Primitive.VOID)
            return null;

        // unwrap primitives
        if (obj instanceof Primitive)
            return((Primitive)obj).getValue();
        else
            return obj;
	}

    /*
        Unwrap Primitive wrappers to their java.lang wrapper values.
		e.g. Primitive(42) becomes Integer(42)
		@see #unwrap( Object )
    */
    public static Object [] unwrap( Object[] args )
    {
		Object [] oa = new Object[ args.length ];
        for(int i=0; i
		The value null is mapped to Primitive.NULL.
		Any value specified with type Void.TYPE is mapped to Primitive.VOID.
	*/
    public static Object wrap(
		Object value, Class type )
    {
        if ( type == Void.TYPE )
            return Primitive.VOID;

        if ( value == null )
            return Primitive.NULL;

		if ( type.isPrimitive() )
			return new Primitive( value );

		return value;
    }


	/**
		Get the appropriate default value per JLS 4.5.4
	*/
	public static Primitive getDefaultValue( Class type )
	{
		if ( type == null || !type.isPrimitive() )
			return Primitive.NULL;
		if ( type == Boolean.TYPE )
			return new Primitive( false );

		// non boolean primitive, get appropriate flavor of zero
		try {
			return new Primitive((int)0).castToType( type, Types.CAST );
		} catch ( UtilEvalError e ) {
			throw new InterpreterError( "bad cast" );
		}
	}

	/**
		Get the corresponding java.lang wrapper class for the primitive TYPE
		class.
		e.g.  Integer.TYPE -> Integer.class
	*/
	public static Class boxType( Class primitiveType )
	{
		Class c = (Class)primitiveToWrapper.get( primitiveType );
		if ( c != null )
			return c;
		throw new InterpreterError( 
			"Not a primitive type: "+ primitiveType );
	}

	/**
		Get the corresponding primitive TYPE class for the java.lang wrapper
		class type.
		e.g.  Integer.class -> Integer.TYPE
	*/
	public static Class unboxType( Class wrapperType )
	{
		Class c = (Class)wrapperToPrimitive.get( wrapperType );
		if ( c != null )
			return c;
		throw new InterpreterError( 
			"Not a primitive wrapper type: "+wrapperType );
	}

	/**
		Cast this bsh.Primitive value to a new bsh.Primitive value
		This is usually a numeric type cast.  Other cases include:
			A boolean can be cast to boolen
			null can be cast to any object type and remains null
			Attempting to cast a void causes an exception
		@param toType is the java object or primitive TYPE class
	*/
	public Primitive castToType( Class toType, int operation ) 
		throws UtilEvalError
	{
		return castPrimitive( 
			toType, getType()/*fromType*/, this/*fromValue*/, 
			false/*checkOnly*/, operation );
	}

	/**
		@param toType is the java primitive TYPE type of the primitive to be
		cast to.
		@param fromType is the java primitive TYPE type of the primitive to be
		cast.  fromType should be null to indicate that the fromValue was null
		or void.
		@param fromValue is, optionally, the value to be converted.  If
		checkOnly is true fromValue must be null.  If checkOnly is false,
		fromValue must be non-null (Primitive.NULL is of course valid).
	*/
	static Primitive castPrimitive( 
		Class toType, Class fromType, Primitive fromValue, 
		boolean checkOnly, int operation ) 
		throws UtilEvalError
	{
		/*
			Lots of preconditions checked here...
			Once things are running smoothly we might comment these out
			(That's what assertions are for).
		*/
		if ( checkOnly && fromValue != null )
			throw new InterpreterError("bad cast param 1");
		if ( !checkOnly && fromValue == null )
			throw new InterpreterError("bad cast param 2");
		if ( fromType != null && !fromType.isPrimitive() )
			throw new InterpreterError("bad fromType:" +fromType);
		if ( fromValue == Primitive.NULL && fromType != null )
			throw new InterpreterError("inconsistent args 1");
		if ( fromValue == Primitive.VOID && fromType != Void.TYPE )
			throw new InterpreterError("inconsistent args 2");

		// can't cast void to anything
		if ( fromType == Void.TYPE )
			if ( checkOnly )
				return Types.INVALID_CAST;
			else
				throw Types.castError( Reflect.normalizeClassName(toType), 
					"void value", operation );

		// unwrap, etc.
		Object value = null; 
		if ( fromValue != null )
			value = fromValue.getValue();

		if ( toType.isPrimitive() )
		{
			// Trying to cast null to primitive type?
			if ( fromType == null )
				if ( checkOnly )
					return Types.INVALID_CAST;
				else
					throw Types.castError(
						"primitive type:" + toType, "Null value", operation );

			// fall through
		} else
		{
			// Trying to cast primitive to an object type
			// Primitive.NULL can be cast to any object type
			if ( fromType == null )
				return checkOnly ? Types.VALID_CAST : 
					Primitive.NULL;

			if ( checkOnly )
				return Types.INVALID_CAST;
			else
				throw Types.castError(
						"object type:" + toType, "primitive value", operation);
		}

		// can only cast boolean to boolean
		if ( fromType == Boolean.TYPE )
		{
			if ( toType != Boolean.TYPE )
				if ( checkOnly )
					return Types.INVALID_CAST;
				else
					throw Types.castError( toType, fromType, operation );

			return checkOnly ? Types.VALID_CAST :
				fromValue;
		}

		// Do numeric cast

		// Only allow legal Java assignment unless we're a CAST operation
		if ( operation == Types.ASSIGNMENT 
			&& !Types.isJavaAssignable( toType, fromType ) 
		) {
			if ( checkOnly )
				return Types.INVALID_CAST;
			else
				throw Types.castError( toType, fromType, operation );
		}

		return checkOnly ? Types.VALID_CAST :
			new Primitive( castWrapper(toType, value) );
	}

	public static boolean isWrapperType( Class type )
	{
		return wrapperToPrimitive.get( type ) != null;
	}

	/**
		Cast a primitive value represented by its java.lang wrapper type to the
		specified java.lang wrapper type.  e.g.  Byte(5) to Integer(5) or
		Integer(5) to Byte(5) 
		@param toType is the java TYPE type
		@param value is the value in java.lang wrapper.
		value may not be null.
	*/
	static Object castWrapper( 
		Class toType, Object value ) 
	{
		if ( !toType.isPrimitive() )
			throw new InterpreterError("invalid type in castWrapper: "+toType);
		if ( value == null )
			throw new InterpreterError("null value in castWrapper, guard");
		if ( value instanceof Boolean && toType != Boolean.TYPE )
			throw new InterpreterError("bad wrapper cast of boolean");

		Class fromType = value.getClass();

		// first promote char to Number type to avoid duplicating code
		if ( value instanceof Character )
			value = new Integer(((Character)value).charValue());

		if ( !(value instanceof Number) )
			throw new InterpreterError("bad type in cast");

		Number number = (Number)value;

		if (toType == Byte.TYPE)
			return new Byte(number.byteValue());
		if (toType == Short.TYPE)
			return new Short(number.shortValue());
		if (toType == Character.TYPE)
			return new Character((char)number.intValue());
		if (toType == Integer.TYPE)
			return new Integer(number.intValue());
		if (toType == Long.TYPE)
			return new Long(number.longValue());
		if (toType == Float.TYPE)
			return new Float(number.floatValue());
		if (toType == Double.TYPE)
			return new Double(number.doubleValue());

		throw new InterpreterError("error in wrapper cast");
	}

}