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require "base62/version"
module Base62
KEYS = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ".freeze
KEYS_HASH = KEYS.each_char.with_index.inject({}) { |h, (k, v)| h[k] = v; h }
BASE = KEYS.length
# Encodes base10 (decimal) number to base62 string.
def self.encode(num)
return "0" if num == 0
return nil if num < 0
str = ""
while num > 0
# prepend base62 charaters
str = KEYS[num % BASE] + str
num = num / BASE
end
str
end
# Decodes base62 string to a base10 (decimal) number.
def self.decode(str)
num = 0
i = 0
len = str.length - 1
# while loop is faster than each_char or other 'idiomatic' way
while i < str.length
pow = BASE**(len - i)
num += KEYS_HASH[str[i]] * pow
i += 1
end
num
end
end