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// Copyright 2017 The Closure Library Authors. All Rights Reserved.
//
// 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.
/**
* @fileoverview Provides some utility methods for calling delegate lists with
* common "calling conventions".
*
* @see goog.delegate.DelegateRegistry
*/
goog.module('goog.delegate.delegates');
/**
* Calls the first delegate, or returns undefined if none are given.
* @param {!Array<T>} delegates
* @param {function(T): R} mapper
* @return {R|undefined}
* @template T, R
*/
exports.callFirst = (delegates, mapper) => {
return delegates.length > 0 ? mapper(delegates[0]) : undefined;
};
/**
* Calls delegates until one returns a defined, non-null result. Returns
* undefined if no such element is found.
* @param {!Array<T>} delegates
* @param {function(T): R|undefined} mapper
* @return {R|undefined}
* @template T, R
*/
exports.callUntilDefinedAndNotNull = (delegates, mapper) => {
for (const delegate of delegates) {
const result = mapper(delegate);
if (result != null) return result;
}
return undefined;
};
/**
* Calls delegates until one returns a truthy result. Returns false if no such
* element is found.
* @param {!Array<T>} delegates
* @param {function(T): R} mapper
* @return {boolean|R}
* @template T, R
*/
exports.callUntilTruthy = (delegates, mapper) => {
for (const delegate of delegates) {
const result = mapper(delegate);
if (result) return result;
}
return false;
};
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