59 lines
1.6 KiB
Ruby
59 lines
1.6 KiB
Ruby
# frozen_string_literal: true
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module RuboCop
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module Cop
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module Gitlab
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# Detects the use of `.keys.first` or `.values.first` and suggests a
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# change to `.each_key.first` or `.each_value.first`. This reduces
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# memory usage and execution time.
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#
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# @example
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#
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# # bad
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#
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# hash.keys.first
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# hash.values.first
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#
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# # good
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#
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# hash.each_key.first
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# hash.each_value.first
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#
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class KeysFirstAndValuesFirst < RuboCop::Cop::Base
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extend RuboCop::Cop::AutoCorrector
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MSG = 'Prefer `.%{autocorrect_method}.first` over `.%{current_method}.first`. ' \
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'This reduces memory usage and execution time.'
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AUTOCORRECT_METHOD = {
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keys: 'each_key',
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values: 'each_value'
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}.freeze
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def_node_matcher :keys_or_values_first, <<~PATTERN
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(send (send ({send const hash lvar} ...) ${:keys :values}) :first)
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PATTERN
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def on_send(node)
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current_method = keys_or_values_first(node)
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return unless current_method
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autocorrect_method = AUTOCORRECT_METHOD.fetch(current_method)
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msg = format(MSG, autocorrect_method: autocorrect_method, current_method: current_method)
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add_offense(node.loc.selector, message: msg) do |corrector|
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replacement = "#{autocorrect_expression(node)}.#{autocorrect_method}.first"
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corrector.replace(node, replacement)
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end
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end
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private
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def autocorrect_expression(node)
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node.receiver.receiver.source
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end
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end
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end
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end
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end
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