/*
 *  Licensed to the Apache Software Foundation (ASF) under one
 *  or more contributor license agreements.  See the NOTICE file
 *  distributed with this work for additional information
 *  regarding copyright ownership.  The ASF licenses this file
 *  to you 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 groovy.transform;

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

/**
 * Marker interface used to indicate that the name of the annotated parameter
 * (or specified optional name) is a valid key name when using named arguments
 * and that the parameter type is applicable for type checking purposes.
 *
 * @since 2.5.0
 */
@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.PARAMETER)
@Repeatable(NamedParams.class)
public @interface NamedParam {
    /**
     * Returns the accepted named-argument key.
     * Defaults to {@link Undefined#STRING}, which indicates the annotated parameter name.
     *
     * @return the named-argument key
     */
    String value() default Undefined.STRING;

    /**
     * Returns the expected value type for the named argument.
     * Defaults to {@link Object}.
     *
     * @return the named-argument type
     */
    Class type() default Object.class;

    /**
     * Indicates whether the named argument must be supplied.
     * Defaults to {@code false}.
     *
     * @return {@code true} if the named argument is required
     */
    boolean required() default false;
}
