module DidYouMean
module Jaro
module_function
def distance(str1, str2)
str1, str2 = str2, str1 if str1.length > str2.length
length1, length2 = str1.length, str2.length
m = 0.0
t = 0.0
range = (length2 / 2).floor - 1
range = 0 if range < 0
flags1 = 0
flags2 = 0
# Avoid duplicating enumerable objects
str1_codepoints = str1.codepoints
str2_codepoints = str2.codepoints
i = 0
while i < length1
last = i + range
j = (i >= range) ? i - range : 0
while j <= last
if flags2[j] == 0 && str1_codepoints[i] == str2_codepoints[j]
flags2 |= (1 << j)
flags1 |= (1 << i)
m += 1
break
end
j += 1
end
i += 1
end
k = i = 0
while i < length1
if flags1[i] != 0
j = index = k
k = while j < length2
index = j
break(j + 1) if flags2[j] != 0
j += 1
end
t += 1 if str1_codepoints[i] != str2_codepoints[index]
end
i += 1
end
t = (t / 2).floor
m == 0 ? 0 : (m / length1 + m / length2 + (m - t) / m) / 3
end
end
module JaroWinkler
WEIGHT = 0.1
THRESHOLD = 0.7
module_function
def distance(str1, str2)
jaro_distance = Jaro.distance(str1, str2)
if jaro_distance > THRESHOLD
codepoints2 = str2.codepoints
prefix_bonus = 0
i = 0
str1.each_codepoint do |char1|
char1 == codepoints2[i] && i < 4 ? prefix_bonus += 1 : break
i += 1
end
jaro_distance + (prefix_bonus * WEIGHT * (1 - jaro_distance))
else
jaro_distance
end
end
end
end
