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@@ -1809,3 +1809,62 @@ fields_iterator :: proc(s: ^string) -> (field: string, ok: bool) {
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s^ = s[len(s):]
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return
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}
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+
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+// `levenshtein_distance` returns the Levenshtein edit distance between 2 strings.
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+// This is a single-row-version of the Wagner–Fischer algorithm, based on C code by Martin Ettl.
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+// Note: allocator isn't used if the length of string b in runes is smaller than 70.
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+levenshtein_distance :: proc(a, b: string, allocator := context.allocator) -> int {
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+ LEVENSHTEIN_DEFAULT_COSTS: []int : {
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+ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
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+ 10, 11, 12, 13, 14, 15, 16, 17, 18, 19,
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+ 20, 21, 22, 23, 24, 25, 26, 27, 28, 29,
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+ 30, 31, 32, 33, 34, 35, 36, 37, 38, 39,
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+ 40, 41, 42, 43, 44, 45, 46, 47, 48, 49,
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+ 50, 51, 52, 53, 54, 55, 56, 57, 58, 59,
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+ 60, 61, 62, 63, 64, 65, 66, 67, 68, 69,
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+ }
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+
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+ m, n := utf8.rune_count_in_string(a), utf8.rune_count_in_string(b)
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+
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+ if m == 0 do return n
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+ if n == 0 do return m
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+
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+ costs: []int
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+
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+ if n + 1 > len(LEVENSHTEIN_DEFAULT_COSTS) {
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+ costs = make([]int, n + 1, allocator)
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+ } else {
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+ costs = LEVENSHTEIN_DEFAULT_COSTS
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+ }
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+
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+ defer if n + 1 > len(LEVENSHTEIN_DEFAULT_COSTS) {
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+ delete(costs, allocator)
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+ }
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+
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+ for k in 0..=n {
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+ costs[k] = k
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+ }
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+
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+ i: int
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+ for c1 in a {
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+ costs[0] = i + 1
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+ corner := i
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+ j: int
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+ for c2 in b {
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+ upper := costs[j + 1]
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+ if c1 == c2 {
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+ costs[j + 1] = corner
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+ } else {
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+ t := upper if upper < corner else corner
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+ costs[j + 1] = (costs[j] if costs[j] < t else t) + 1
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+ }
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+
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+ corner = upper
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+ j += 1
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+ }
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+
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+ i += 1
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+ }
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+
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+ return costs[n]
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+}
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hikari