sneeker
c490488423
Levenshtein with a cutoff, returning the closest valid name at a position, or nothing when no candidate is close enough.
34 lines
1015 B
OCaml
34 lines
1015 B
OCaml
let distance a b =
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let la = String.length a and lb = String.length b in
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if la = 0 then lb
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else if lb = 0 then la
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else begin
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let prev = Array.init (lb + 1) (fun j -> j) in
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let cur = Array.make (lb + 1) 0 in
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for i = 1 to la do
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cur.(0) <- i;
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for j = 1 to lb do
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let cost = if a.[i - 1] = b.[j - 1] then 0 else 1 in
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cur.(j) <- min (min (cur.(j - 1) + 1) (prev.(j) + 1)) (prev.(j - 1) + cost)
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done;
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Array.blit cur 0 prev 0 (lb + 1)
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done;
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prev.(lb)
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end
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let closest word candidates =
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let limit = 1 + String.length word / 3 in
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List.fold_left
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(fun best c ->
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let d = distance word c in
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match best with
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| Some (_, bd) when bd <= d -> best
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| _ -> if d <= limit then Some (c, d) else best)
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None candidates
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|> Option.map fst
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let hint word candidates =
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match closest word candidates with
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| Some c -> Printf.sprintf "did you mean %S?" c
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| None -> Printf.sprintf "expected one of: %s" (String.concat ", " candidates)
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