57 lines
1.7 KiB
JavaScript
57 lines
1.7 KiB
JavaScript
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/**
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* Copyright 2014-present, Facebook, Inc.
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* All rights reserved.
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*
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* This source code is licensed under the BSD-style license found in the
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* LICENSE file in the root directory of this source tree. An additional grant
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* of patent rights can be found in the PATENTS file in the same directory.
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*
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*
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*/
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'use strict';
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var _prodInvariant = require('./reactProdInvariant');
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var invariant = require('fbjs/lib/invariant');
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/**
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* Accumulates items that must not be null or undefined into the first one. This
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* is used to conserve memory by avoiding array allocations, and thus sacrifices
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* API cleanness. Since `current` can be null before being passed in and not
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* null after this function, make sure to assign it back to `current`:
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*
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* `a = accumulateInto(a, b);`
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*
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* This API should be sparingly used. Try `accumulate` for something cleaner.
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*
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* @return {*|array<*>} An accumulation of items.
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*/
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function accumulateInto(current, next) {
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!(next != null) ? process.env.NODE_ENV !== 'production' ? invariant(false, 'accumulateInto(...): Accumulated items must not be null or undefined.') : _prodInvariant('30') : void 0;
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if (current == null) {
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return next;
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}
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// Both are not empty. Warning: Never call x.concat(y) when you are not
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// certain that x is an Array (x could be a string with concat method).
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if (Array.isArray(current)) {
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if (Array.isArray(next)) {
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current.push.apply(current, next);
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return current;
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}
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current.push(next);
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return current;
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}
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if (Array.isArray(next)) {
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// A bit too dangerous to mutate `next`.
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return [current].concat(next);
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}
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return [current, next];
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}
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module.exports = accumulateInto;
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