35 lines
803 B
Plaintext
35 lines
803 B
Plaintext
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/**
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* Copyright (c) 2013-present, Facebook, Inc.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*
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* @providesModule minBy
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* @flow
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*/
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var compareNumber = (a, b) => a - b;
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/**
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* Returns the minimum element as measured by a scoring function f. Returns the
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* first such element if there are ties.
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*/
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function minBy<A, B>(as: Iterable<A>, f: (a: A) => B, compare?: ?(u: B, v: B) => number): ?A {
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compare = compare || (compareNumber: any);
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var minA = undefined;
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var minB = undefined;
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var seenFirst = false;
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for (var a of as) {
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var b = f(a);
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if (!seenFirst || compare(b, (minB: any)) < 0) {
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minA = a;
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minB = b;
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seenFirst = true;
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}
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}
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return minA;
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}
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module.exports = minBy;
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