39 lines
1.3 KiB
JavaScript
39 lines
1.3 KiB
JavaScript
/**
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* @license
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* Copyright (C) 2017 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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/**
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* @template T
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* @param {!Array<T>} array
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* @param {!Function} fn An iteratee function to be passed each element of
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* the array in order. Must return a promise, and the following
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* iteration will not begin until resolution of the promise returned by
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* the previous iteration.
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*
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* An optional second argument to fn is a callback that will halt the
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* loop if called.
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* @return {!Promise<undefined>}
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*/
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export function asyncForeach(array, fn) {
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if (!array.length) { return Promise.resolve(); }
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let stop = false;
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const stopCallback = () => { stop = true; };
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return fn(array[0], stopCallback).then(exit => {
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if (stop) { return Promise.resolve(); }
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return asyncForeach(array.slice(1), fn);
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});
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}
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