38 lines
1.2 KiB
TypeScript
38 lines
1.2 KiB
TypeScript
/*
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Copyright 2023 New Vector Ltd
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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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http://www.apache.org/licenses/LICENSE-2.0
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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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* Gets the index of the last element in the array to satsify the given
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* predicate.
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*/
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// TODO: remove this once TypeScript recognizes the existence of
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// Array.prototype.findLastIndex
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export function findLastIndex<T>(
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array: T[],
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predicate: (item: T) => boolean
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): number | null {
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for (let i = array.length - 1; i >= 0; i--) {
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if (predicate(array[i])) return i;
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}
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return null;
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}
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/**
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* Counts the number of elements in an array that satsify the given predicate.
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*/
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export const count = <T>(array: T[], predicate: (item: T) => boolean): number =>
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array.reduce((acc, item) => (predicate(item) ? acc + 1 : acc), 0);
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