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36 lines
1.2 KiB
TypeScript
36 lines
1.2 KiB
TypeScript
/**
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* Compares a given range to the value, returning the relative position.
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*
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* If the returned value is 1, the value sits AFTER the range.
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* If the returned value is 0, the value sits WITHIN the range.
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* If the returned value is -1, the value sits BEFORE the range.
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* The range given is considered to be inclusive (e.g. 6 sits WITHIN 6-10).
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*
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* @param value The value.
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* @param range The range, two positive numbers split by a single dash.
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* @returns {number} The relative position of the value to the range as -1, 0 or 1.
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*/
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function compareASN(value: number, range: string): number {
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const [start, end] = range.split("-", 2) as [string, string];
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if (value < parseInt(start)) return -1;
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if (value > parseInt(end)) return 1;
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return 0;
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}
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/**
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* Find the range in which a given ASN exists via binary search. If not found, -1 is used.
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*/
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export function findASN(asn: number, ranges: string[]) {
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let start = 0;
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let end = ranges.length - 1;
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while (start <= end) {
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const mid = Math.floor((start + end) / 2);
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const comparison = compareASN(asn, ranges[mid] as string);
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if (comparison == 0) return mid; // Success case
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if (comparison == -1) end = mid - 1;
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else start = mid + 1;
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}
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return -1; // Failure case
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}
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