/*
 * Copyright 2002-2006,2009 The Apache Software Foundation.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.opensymphony.xwork2.validator.annotations;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
 * <!-- START SNIPPET: description -->
 * This non-field level validator validates a supplied regular expression.
 * <!-- END SNIPPET: description -->
 *
 * <p/> <u>Annotation usage:</u>
 *
 * <!-- START SNIPPET: usage -->
 * <p/>The annotation must be applied at method level.
 * <!-- END SNIPPET: usage -->
 *
 * <p/> <u>Annotation parameters:</u>
 *
 * <!-- START SNIPPET: parameters -->
 * <table class='confluenceTable'>
 * <tr>
 * <th class='confluenceTh'> Parameter </th>
 * <th class='confluenceTh'> Required </th>
 * <th class='confluenceTh'> Default </th>
 * <th class='confluenceTh'> Notes </th>
 * </tr>
 * <tr>
 * <td class='confluenceTd'>message</td>
 * <td class='confluenceTd'>yes</td>
 * <td class='confluenceTd'>&nbsp;</td>
 * <td class='confluenceTd'>field error message</td>
 * </tr>
 * <tr>
 * <td class='confluenceTd'>key</td>
 * <td class='confluenceTd'>no</td>
 * <td class='confluenceTd'>&nbsp;</td>
 * <td class='confluenceTd'>i18n key from language specific properties file.</td>
 * </tr>
 * <tr>
 * <td class='confluenceTd'>shortCircuit</td>
 * <td class='confluenceTd'>no</td>
 * <td class='confluenceTd'>false</td>
 * <td class='confluenceTd'>If this validator should be used as shortCircuit.</td>
 * </tr>
 * <tr>
 * <td class='confluenceTd'> expression </td>
 * <td class='confluenceTd'> yes </td>
 * <td class='confluenceTd'>&nbsp;</td>
 * <td class='confluenceTd'> An OGNL expression that returns a boolean value.  </td>
 * </tr>
 * </table>
 * <!-- END SNIPPET: parameters -->
 *
 * <p/> <u>Example code:</u>
 *
 * <pre>
 * <!-- START SNIPPET: example -->
 * &#64;ExpressionValidator(message = "Default message", key = "i18n.key", shortCircuit = true, expression = "an OGNL expression" )
 * <!-- END SNIPPET: example -->
 * </pre>
 *
 * @author Rainer Hermanns
 * @version $Id$
 */
@Retention(RetentionPolicy.RUNTIME)
@Target({ ElementType.METHOD})
public @interface ExpressionValidator {

    /**
     * The expressions to validate.
     * An OGNL expression that returns a boolean value.
     */
    String expression();

    /**
     * The default error message for this validator.
     * NOTE: It is required to set a message, if you are not using the message key for 18n lookup!
     */
    String message() default "";

    /**
     * The message key to lookup for i18n.
     */
    String key() default "";

    /**
     * If this is activated, the validator will be used as short-circuit.
     *
     * Adds the short-circuit="true" attribute value if <tt>true</tt>.
     *
     */
    boolean shortCircuit() default false;

}
