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 * Copyright 2000-2020 JetBrains s.r.o.
 *
 * 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
 *
 * https://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 org.jetbrains.annotations.NonNls;

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:
@Pattern("[\\dA-Fa-f]{8}-[\\dA-Fa-f]{4}-[\\dA-Fa-f]{4}-[\\dA-Fa-f]{4}-[\\dA-Fa-f]{12}")
@interface UUID {}


Note that using the derived annotation as meta-annotation is not supported. 
Meta-annotation works only one level deep.
See Also:
RegExp/**
 * 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.
 * <p>
 * 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>
 * <p>
 * Note that using the derived annotation as meta-annotation is not supported. 
 * Meta-annotation works only one level deep.
 *
 * @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.
/**
     * 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")
    @NonNls
    String value();
}