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 *  Patrick Niemeyer ([email protected])                                           *
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 *  http://www.pat.net/~pat/                                                 *
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package bsh;

class BSHUnaryExpression extends SimpleNode implements ParserConstants {
        public int kind;

        public boolean postfix = false;

        BSHUnaryExpression(int id) {
                super(id);
        }

        public Object eval(CallStack callstack, Interpreter interpreter) throws EvalError {
                SimpleNode node = (SimpleNode) jjtGetChild(0);

                // If this is a unary increment of decrement (either pre or
                // postfix)
                // then we need an LHS to which to assign the result. Otherwise
                // just do the unary operation for the value.
                try {
                        if (kind == INCR || kind == DECR) {
                                LHS lhs = ((BSHPrimaryExpression) node).toLHS(callstack, interpreter);
                                return lhsUnaryOperation(lhs, interpreter.getStrictJava());
                        } else
                                return unaryOperation(node.eval(callstack, interpreter), kind);
                } catch (UtilEvalError e) {
                        throw e.toEvalError(this, callstack);
                }
        }

        private Object lhsUnaryOperation(LHS lhs, boolean strictJava) throws UtilEvalError {
                if (Interpreter.DEBUG)
                        Interpreter.debug("lhsUnaryOperation");
                Object prevalue, postvalue;
                prevalue = lhs.getValue();
                postvalue = unaryOperation(prevalue, kind);

                Object retVal;
                if (postfix)
                        retVal = prevalue;
                else
                        retVal = postvalue;

                lhs.assign(postvalue, strictJava);
                return retVal;
        }

        private Object unaryOperation(Object op, int kind) throws UtilEvalError {
                if (op instanceof Boolean || op instanceof Character || op instanceof Number)
                        return primitiveWrapperUnaryOperation(op, kind);

                if (!(op instanceof Primitive))
                        throw new UtilEvalError("Unary operation " + tokenImage[kind] + " inappropriate for object");

                return Primitive.unaryOperation((Primitive) op, kind);
        }

        private Object primitiveWrapperUnaryOperation(Object val, int kind) throws UtilEvalError {
                Class operandType = val.getClass();
                Object operand = Primitive.promoteToInteger(val);

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

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

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




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