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Versions: 177
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Stored size: 1.02 KB
Contents
module BookKeeping
VERSION = 1
end
class RotationalCipher
SMALL_LETTERS_RANGE = (97..122)
BIG_LETTERS_RANGE = (65..90)
ROTATION_MODIFIER = 1
attr_reader :text
def initialize(text, key)
@text = text
@shift_key = key
end
def self.rotate(text, key)
new(text, key).rotate
end
def rotate
text.split('').map { |char| shift_char(char) }.join
end
private
def shift_char(char)
shift_ascii(char.ord).chr
end
def shift_key
@shift_key % 26
end
def shift_ascii(char_ascii)
case char_ascii
when SMALL_LETTERS_RANGE
shift_within(char_ascii, SMALL_LETTERS_RANGE.min, SMALL_LETTERS_RANGE.max)
when BIG_LETTERS_RANGE
shift_within(char_ascii, BIG_LETTERS_RANGE.min, BIG_LETTERS_RANGE.max)
else
char_ascii
end
end
def shift_within(char_ascii, lower_limit, upper_limit)
shifted_ascii = char_ascii + shift_key
return shifted_ascii if shifted_ascii <= upper_limit
lower_limit + (shifted_ascii - upper_limit - ROTATION_MODIFIER)
end
end
Version data entries
177 entries across 177 versions & 1 rubygems