60 lines
1.3 KiB
Plaintext
60 lines
1.3 KiB
Plaintext
// @flow strict
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/**
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* Returns a number indicating whether a reference string comes before, or after,
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* or is the same as the given string in natural sort order.
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*
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* See: https://en.wikipedia.org/wiki/Natural_sort_order
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*
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*/
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export default function naturalCompare(aStr: string, bStr: string): number {
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let aIdx = 0;
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let bIdx = 0;
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while (aIdx < aStr.length && bIdx < bStr.length) {
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let aChar = aStr.charCodeAt(aIdx);
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let bChar = bStr.charCodeAt(bIdx);
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if (isDigit(aChar) && isDigit(bChar)) {
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let aNum = 0;
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do {
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++aIdx;
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aNum = aNum * 10 + aChar - DIGIT_0;
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aChar = aStr.charCodeAt(aIdx);
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} while (isDigit(aChar) && aNum > 0);
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let bNum = 0;
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do {
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++bIdx;
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bNum = bNum * 10 + bChar - DIGIT_0;
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bChar = bStr.charCodeAt(bIdx);
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} while (isDigit(bChar) && bNum > 0);
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if (aNum < bNum) {
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return -1;
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}
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if (aNum > bNum) {
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return 1;
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}
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} else {
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if (aChar < bChar) {
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return -1;
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}
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if (aChar > bChar) {
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return 1;
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}
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++aIdx;
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++bIdx;
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}
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}
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return aStr.length - bStr.length;
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}
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const DIGIT_0 = 48;
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const DIGIT_9 = 57;
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function isDigit(code: number): boolean {
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return !isNaN(code) && DIGIT_0 <= code && code <= DIGIT_9;
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}
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