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# frozen_string_literal: true
module RuboCop
module Cop
module Lint
# Certain numeric operations have no impact, being:
# Adding or subtracting 0, multiplying or dividing by 1 or raising to the power of 1.
# These are probably leftover from debugging, or are mistakes.
#
# @example
#
# # bad
# x + 0
# x - 0
# x * 1
# x / 1
# x ** 1
#
# # good
# x
#
# # bad
# x += 0
# x -= 0
# x *= 1
# x /= 1
# x **= 1
#
# # good
# x = x
#
class UselessNumericOperation < Base
extend AutoCorrector
MSG = 'Do not apply inconsequential numeric operations to variables.'
RESTRICT_ON_SEND = %i[+ - * / **].freeze
# @!method useless_operation?(node)
def_node_matcher :useless_operation?, '(send (send nil? $_) $_ (int $_))'
# @!method useless_abbreviated_assignment?(node)
def_node_matcher :useless_abbreviated_assignment?, '(op-asgn (lvasgn $_) $_ (int $_))'
def on_send(node)
return unless useless_operation?(node)
variable, operation, number = useless_operation?(node)
return unless useless?(operation, number)
add_offense(node) do |corrector|
corrector.replace(node, variable)
end
end
def on_op_asgn(node)
return unless useless_abbreviated_assignment?(node)
variable, operation, number = useless_abbreviated_assignment?(node)
return unless useless?(operation, number)
add_offense(node) do |corrector|
corrector.replace(node, "#{variable} = #{variable}")
end
end
private
def useless?(operation, number)
if number.zero?
true if %i[+ -].include?(operation)
elsif number == 1
true if %i[* / **].include?(operation)
end
end
end
end
end
end
Version data entries
8 entries across 8 versions & 1 rubygems