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# frozen_string_literal: true
module RuboCop
module Cop
module Performance
# This cop identifies uses of `Range#include?` and `Range#member?`, which iterates over each
# item in a `Range` to see if a specified item is there. In contrast,
# `Range#cover?` simply compares the target item with the beginning and
# end points of the `Range`. In a great majority of cases, this is what
# is wanted.
#
# This cop is `Safe: false` by default because `Range#include?` (or `Range#member?`) and
# `Range#cover?` are not equivalent behaviour.
#
# @example
# # bad
# ('a'..'z').include?('b') # => true
# ('a'..'z').member?('b') # => true
#
# # good
# ('a'..'z').cover?('b') # => true
#
# # Example of a case where `Range#cover?` may not provide
# # the desired result:
#
# ('a'..'z').cover?('yellow') # => true
class RangeInclude < Cop
MSG = 'Use `Range#cover?` instead of `Range#%<bad_method>s`.'
# TODO: If we traced out assignments of variables to their uses, we
# might pick up on a few more instances of this issue
# Right now, we only detect direct calls on a Range literal
# (We don't even catch it if the Range is in double parens)
def_node_matcher :range_include, <<~PATTERN
(send {irange erange (begin {irange erange})} ${:include? :member?} ...)
PATTERN
def on_send(node)
range_include(node) do |bad_method|
message = format(MSG, bad_method: bad_method)
add_offense(node, location: :selector, message: message)
end
end
def autocorrect(node)
->(corrector) { corrector.replace(node.loc.selector, 'cover?') }
end
end
end
end
end
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