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# frozen_string_literal: true
module RuboCop
module Cop
module Performance
class ReadlinesEach < RuboCop::Cop::Base
extend RuboCop::Cop::AutoCorrector
MESSAGE = 'Avoid `IO.readlines.each`, since it reads contents into memory in full. ' \
'Use `IO.each_line` or `IO.each` instead.'
def_node_matcher :full_file_read_via_class?, <<~PATTERN
(send
(send (const nil? {:IO :File}) :readlines _) :each)
PATTERN
def_node_matcher :full_file_read_via_instance?, <<~PATTERN
(... (... :readlines) :each)
PATTERN
def on_send(node)
return unless full_file_read_via_class?(node) || full_file_read_via_instance?(node)
add_offense(node.loc.selector, message: MESSAGE) do |corrector|
corrector.replace(node.loc.expression, node.source.gsub('readlines.each', 'each_line'))
end
end
end
end
end
end
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