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single_line_comparison.rb
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single_line_comparison.rb
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# frozen_string_literal: true
module RuboCop
module Cop
module InternalAffairs
# Enforces the use of `node.single_line?` instead of
# comparing `first_line` and `last_line` for equality.
#
# @example
# # bad
# node.loc.first_line == node.loc.last_line
#
# # bad
# node.loc.last_line == node.loc.first_line
#
# # bad
# node.loc.line == node.loc.last_line
#
# # bad
# node.loc.last_line == node.loc.line
#
# # bad
# node.first_line == node.last_line
#
# # good
# node.single_line?
#
class SingleLineComparison < Base
extend AutoCorrector
MSG = 'Use `%<preferred>s`.'
RESTRICT_ON_SEND = %i[== !=].freeze
# @!method single_line_comparison(node)
def_node_matcher :single_line_comparison, <<~PATTERN
{
(send (send $_receiver {:line :first_line}) {:== :!=} (send _receiver :last_line))
(send (send $_receiver :last_line) {:== :!=} (send _receiver {:line :first_line}))
}
PATTERN
def on_send(node)
return unless (receiver = single_line_comparison(node))
bang = node.method?(:!=) ? '!' : ''
preferred = "#{bang}#{extract_receiver(receiver)}.single_line?"
add_offense(node, message: format(MSG, preferred: preferred)) do |corrector|
corrector.replace(node, preferred)
end
end
private
def extract_receiver(node)
node = node.receiver if node.send_type? && %i[loc source_range].include?(node.method_name)
node.source
end
end
end
end
end