102 lines
1.9 KiB
TypeScript
102 lines
1.9 KiB
TypeScript
function min (d0: number, d1: number, d2: number, bx: number, ay: number) {
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return d0 < d1 || d2 < d1
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? d0 > d2
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? d2 + 1
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: d0 + 1
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: bx === ay
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? d1
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: d1 + 1
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}
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/**
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* @see https://github.com/gustf/js-levenshtein
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*/
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export function levenshteinDistance (a: string, b: string): number {
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if (a === b) {
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return 0
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}
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if (a.length > b.length) {
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const tmp = a
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a = b
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b = tmp
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}
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let la = a.length
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let lb = b.length
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while (la > 0 && (a.charCodeAt(la - 1) === b.charCodeAt(lb - 1))) {
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la--
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lb--
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}
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let offset = 0
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while (offset < la && (a.charCodeAt(offset) === b.charCodeAt(offset))) {
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offset++
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}
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la -= offset
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lb -= offset
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if (la === 0 || lb < 3) {
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return lb
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}
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let x = 0
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let y: number
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let d0: number
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let d1: number
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let d2: number
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let d3: number
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let dd: number
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let dy: number
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let ay: number
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let bx0: number
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let bx1: number
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let bx2: number
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let bx3: number
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const vector: number[] = []
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for (y = 0; y < la; y++) {
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vector.push(y + 1)
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vector.push(a.charCodeAt(offset + y))
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}
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const len = vector.length - 1
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for (; x < lb - 3;) {
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bx0 = b.charCodeAt(offset + (d0 = x))
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bx1 = b.charCodeAt(offset + (d1 = x + 1))
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bx2 = b.charCodeAt(offset + (d2 = x + 2))
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bx3 = b.charCodeAt(offset + (d3 = x + 3))
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dd = (x += 4)
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for (y = 0; y < len; y += 2) {
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dy = vector[y]
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ay = vector[y + 1]
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d0 = min(dy, d0, d1, bx0, ay)
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d1 = min(d0, d1, d2, bx1, ay)
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d2 = min(d1, d2, d3, bx2, ay)
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dd = min(d2, d3, dd, bx3, ay)
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vector[y] = dd
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d3 = d2
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d2 = d1
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d1 = d0
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d0 = dy
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}
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}
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for (; x < lb;) {
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bx0 = b.charCodeAt(offset + (d0 = x))
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dd = ++x
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for (y = 0; y < len; y += 2) {
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dy = vector[y]
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vector[y] = dd = min(dy, d0, dd, bx0, vector[y + 1])
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d0 = dy
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}
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}
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return dd
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}
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