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matchIndexesToRanges.js
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matchIndexesToRanges.js
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/**
* Copyright (c) 2017-present, Facebook, Inc.
* All rights reserved.
*
* This source code is licensed under the BSD-style license found in the
* LICENSE file in the root directory of this source tree. An additional grant
* of patent rights can be found in the PATENTS file in the same directory.
*
* @flow strict
* @format
*/
type MatchRange = [/* start */ number, /* end */ number];
export default function matchIndexesToRanges(
matchIndexes: Array<number>,
): Array<MatchRange> {
let streakOngoing = false;
let start = 0;
const ranges = [];
// Collapse consecutive values for consecutive indexes into range pairs.
// Do this in O(n) where n is the number of matchIndexes (ie. less than the length of the path).
matchIndexes.forEach((i, n) => {
if (matchIndexes[n + 1] === i + 1) {
if (!streakOngoing) {
start = i;
streakOngoing = true;
}
} else {
if (streakOngoing) {
ranges.push([start, i + 1]);
streakOngoing = false;
} else {
ranges.push([i, i + 1]);
}
start = i + 1;
}
});
return ranges;
}