expression.java

来自「OpenJMS是一个开源的Java Message Service API 1.」· Java 代码 · 共 81 行

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package org.exolab.jms.selector;

import javax.jms.Message;


/**
 * This class is the base class for all expressions.
 *
 * @version     $Revision: 1.1 $ $Date: 2004/11/26 01:50:44 $
 * @author      <a href="mailto:[e-mail]">Tim Anderson</a>
 * @see         javax.jms.Message
 * @see         org.exolab.jms.selector.SObject
 * @see         org.exolab.jms.selector.TypeMismatchException
 **/
public interface Expression {

    /**
     * Evaluate the expression
     *
     * @param msg the message to use to obtain any header identifier and
     * property values
     * @return the evaluated result, or <code>null</code> if the value of the
     *  expression is unknown
     * @throws TypeMismatchException if the expression tries to evaluate
     * mismatched types.
     */
    SObject evaluate(Message msg) throws TypeMismatchException;

    /**
     * Return a string representation of this expression. This
     * should be compatible with the selector syntax.
     *
     * @return a string representation of this expression
     */
    String toString();

}