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Contents
# frozen_string_literal: true
module RuboCop
module Cop
module Style
# This cop checks for places where `Integer#even?` or `Integer#odd?`
# can be used.
#
# @example
#
# # bad
# if x % 2 == 0
# end
#
# # good
# if x.even?
# end
class EvenOdd < Cop
MSG = 'Replace with `Integer#%<method>s?`.'
def_node_matcher :even_odd_candidate?, <<~PATTERN
(send
{(send $_ :% (int 2))
(begin (send $_ :% (int 2)))}
${:== :!=}
(int ${0 1}))
PATTERN
def on_send(node)
even_odd_candidate?(node) do |_base_number, method, arg|
replacement_method = replacement_method(arg, method)
add_offense(node, message: format(MSG, method: replacement_method))
end
end
def autocorrect(node)
even_odd_candidate?(node) do |base_number, method, arg|
replacement_method = replacement_method(arg, method)
correction = "#{base_number.source}.#{replacement_method}?"
->(corrector) { corrector.replace(node, correction) }
end
end
private
def replacement_method(arg, method)
case arg
when 0
method == :== ? :even : :odd
when 1
method == :== ? :odd : :even
end
end
end
end
end
end
Version data entries
15 entries across 15 versions & 3 rubygems