@a-s8h/liblevenshtein

distance = (algorithm) -> algorithm = 'standard' unless algorithm in [ 'standard' 'transposition' 'merge_and_split' ] f = (u, t) -> if t < u.length u[t+1..] else '' # Source: http://www.fmi.uni-sofia.bg/fmi/logic/theses/mitankin-en.pdf switch algorithm # Calculates the Levenshtein distance between words v and w, using the # following primitive operations: deletion, insertion, and substitution. when 'standard' then do (; distance) -> memoized_distance = {} distance = (v, w) -> key = if v.localeCompare(w) < 0 v + '\0' + w else w + '\0' + v if (value = memoized_distance[key]) isnt `undefined` value else if v is '' memoized_distance[key] = w.length else if w is '' memoized_distance[key] = v.length else # v.length > 0 and w.length > 0 a = v[0]; s = v[1..] b = w[0]; t = w[1..] # Discard identical characters while a is b and s.length > 0 and t.length > 0 a = s[0]; v = s; s = s[1..] b = t[0]; w = t; t = t[1..] # s.length is 0 or t.length is 0 return memoized_distance[key] = s.length || t.length if a is b p = distance(s,w) return memoized_distance[key] = 1 if p is 0 min = p p = distance(v,t) return memoized_distance[key] = 1 if p is 0 min = p if p < min p = distance(s,t) return memoized_distance[key] = 1 if p is 0 min = p if p < min return memoized_distance[key] = 1 + min # Calculates the Levenshtein distance between words v and w, using the # following primitive operations: deletion, insertion, substitution, and # transposition. when 'transposition' then do (; distance) -> memoized_distance = {} distance = (v, w) -> key = if v.localeCompare(w) < 0 v + '\0' + w else w + '\0' + v if (value = memoized_distance[key]) isnt `undefined` value else if v is '' memoized_distance[key] = w.length else if w is '' memoized_distance[key] = v.length else # v.length > 0 and w.length > 0 a = v[0]; x = v[1..] b = w[0]; y = w[1..] # Discard identical characters while a is b and x.length > 0 and y.length > 0 a = x[0]; v = x; x = x[1..] b = y[0]; w = y; y = y[1..] # x.length is 0 or y.length is 0 return memoized_distance[key] = x.length || y.length if a is b p = distance(x,w) return memoized_distance[key] = 1 if p is 0 min = p p = distance(v,y) return memoized_distance[key] = 1 if p is 0 min = p if p < min p = distance(x,y) return memoized_distance[key] = 1 if p is 0 min = p if p < min a1 = x[0] # prefix character of x b1 = y[0] # prefix character of y if a is b1 and a1 is b p = distance(f(v,1), f(w,1)) return memoized_distance[key] = 1 if p is 0 min = p if p < min return memoized_distance[key] = 1 + min # Calculates the Levenshtein distance between words v and w, using the # following primitive operations: deletion, insertion, substitution, # merge, and split. when 'merge_and_split' then do (; distance) -> memoized_distance = {} distance = (v, w) -> key = if v.localeCompare(w) < 0 v + '\0' + w else w + '\0' + v if (value = memoized_distance[key]) isnt `undefined` value else if v is '' memoized_distance[key] = w.length else if w is '' memoized_distance[key] = v.length else # v.length > 0 and w.length > 0 a = v[0]; x = v[1..] b = w[0]; y = w[1..] # Discard identical characters while a is b and x.length > 0 and y.length > 0 a = x[0]; v = x; x = x[1..] b = y[0]; w = y; y = y[1..] # x.length is 0 or y.length is 0 return memoized_distance[key] = x.length || y.length if a is b p = distance(x,w) return memoized_distance[key] = 1 if p is 0 min = p p = distance(v,y) return memoized_distance[key] = 1 if p is 0 min = p if p < min p = distance(x,y) return memoized_distance[key] = 1 if p is 0 min = p if p < min if w.length > 1 p = distance(x, f(w,1)) return memoized_distance[key] = 1 if p is 0 min = p if p < min if v.length > 1 p = distance(f(v,1), y) return memoized_distance[key] = 1 if p is 0 min = p if p < min return memoized_distance[key] = 1 + min global = if typeof exports is 'object' exports else if typeof window is 'object' window else this global['levenshtein'] ||= {} global['levenshtein']['distance'] = distance