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 *
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 */

package org.exolab.jms.selector;


/**
 * This class is the base class for all unary operators.
 *
 * @version     $Revision: 1.1 $ $Date: 2004/11/26 01:50:45 $
 * @author      <a href="mailto:tma@netspace.net.au">Tim Anderson</a>
 * @see         Expression
 * @see         Operator
 */
abstract class UnaryOperator extends Operator {

    /**
     * The operand to apply the operator to
     */
    private final Expression _operand;


    /**
     * Construct a new <code>UnaryOperator</code>
     *
     * @param operator the operator
     * @param operand the operand
     */
    public UnaryOperator(final String operator, final Expression operand) {
        super(operator);
        _operand = operand;
    }

    /**
     * Returns the operand
     *
     * @return the operand
     */
    public final Expression operand() {
        return _operand;
    }

    /**
     * Return a string representation of this expression.
     *
     * @return a string representation of this expression
     */
    public final String toString() {
        return "(" + operator() + " " + _operand.toString() + ")";
    }

} //-- UnaryOperator