user/src/jsinterop/annotations/JsOptional.java

/*
 * Copyright 2016 Google Inc.
 *
 * 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 jsinterop.annotations;

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;

/**
 * JsOptional marks a parameter in a method as optional indicating that the argument can be omitted
 * from the function call when called from JavaScript side.
 *
 * <p>Note that JsOptional can only be used in a JsConstructor, a JsMethod or a JsFunction method.
 * An optional argument cannot precede a non-optional argument (a vararg is considered an
 * optional argument).
 *
 * <p>This annotation is informational in the GWT compiler but other compilers or tools might use it
 * for example to annotate types in the output JavaScript program.
 */
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.PARAMETER)
@Documented
public @interface JsOptional {
}