binaryoperator.java

实现了Jms的服务器源码,支持多种适配器,DB,FTP,支持多种数据库

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package org.exolab.jms.selector;


/**
 * This class is the base class for all expressions that are binary
 * operators.
 *
 * @version     $Revision: 1.4 $ $Date: 2003/08/09 15:49:50 $
 * @author      <a href="mailto:[e-mail]">Tim Anderson</a>
 * @see         Expression
 * @see         Operator
 */
abstract class BinaryOperator extends Operator {

    /**
     * The left-hand side of the binary expression
     */
    private final Expression _lhs;

    /**
     * The right-hand side of the binary expression
     */
    private final Expression _rhs;

    /**
     * Construct a new <code>BinaryOperator</code>
     *
     * @param operator the operator
     * @param lhs the left hand side of the expression
     * @param rhs the right hand side of the expression
     */
    public BinaryOperator(final String operator, final Expression lhs,
                          final Expression rhs) {
        super(operator);
        _lhs = lhs;
        _rhs = rhs;
    }

    /**
     * Returns the left hand side of the expression
     *
     * @return the left hand side of the expression
     */
    public final Expression left() {
        return _lhs;
    }

    /**
     * Returns the right hand side of the expression
     *
     * @return the right hand side of the expression
     */
    public final Expression right() {
        return _rhs;
    }

    /**
     * Returns a stringified version of the expression
     *
     * @return a stringified version of the expression
     */
    public final String toString() {
        StringBuffer result = new StringBuffer();
        result.append('(');
        result.append(_lhs.toString());
        result.append(' ');
        result.append(operator());
        result.append(' ');
        result.append(_rhs.toString());
        result.append(')');
        return result.toString();
    }

} //-- BinaryOperator