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package org.checkerframework.checker.regex.qual;
import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import org.checkerframework.framework.qual.SubtypeOf;
/**
* If a type is annotated as {@code @Regex(n)}, then the run-time value is a regular expression with
* n capturing groups.
*
* For example, if an expression's type is @Regex(2) String, then at run time its value
* will be a legal regular expression with at least two capturing groups. The type states that
* possible run-time values include {@code "(a*)(b*)"}, {@code "a(b?)c(d?)e"}, and {@code
* "(.)(.)(.)"}, but not {@code "hello"} nor {@code "(good)bye"} nor {@code "(a*)(b*)("}.
*
* @checker_framework.manual #regex-checker Regex Checker
*/
@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.TYPE_USE, ElementType.TYPE_PARAMETER})
@SubtypeOf(UnknownRegex.class)
public @interface Regex {
/** The number of groups in the regular expression. Defaults to 0. */
int value() default 0;
}