/*
 * Copyright 2006 Sascha Weinreuter
 *
 * 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 org.intellij.lang.annotations;

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

/**
 * Specifies that an element of the program represents a string that must completely match given regular expression.
 * Code editors may use this annotation to report errors if the literals that assigned to the annotated variables, 
 * passed as arguments to the annotated parameters, or returned from the annotated methods, do not match the supplied
 * pattern.
 *
 * This annotation also could be used as a meta-annotation, to define other annotations for convenience. 
 * E.g. the following annotation could be defined to annotate the strings that represent UUIDs:
 * 
 * <pre>
 * &#64;Pattern("[\\dA-Fa-f]{8}-[\\dA-Fa-f]{4}-[\\dA-Fa-f]{4}-[\\dA-Fa-f]{4}-[\\dA-Fa-f]{12}")
 * &#64;interface UUID {}
 * </pre>
 *
 * @see RegExp
 */
@Retention(RetentionPolicy.CLASS)
@Target({ METHOD, FIELD, PARAMETER, LOCAL_VARIABLE, ANNOTATION_TYPE })
public @interface Pattern {
    /**
     * A regular expression that matches all the valid string literals that assigned to the annotated variables, 
     * passed as arguments to the annotated parameters, or returned from the annotated methods.
     */
    @Language("RegExp")
    String value();
}
