lib/rubocop/cop/style/redundant_array_constructor.rb
# frozen_string_literal: true
module RuboCop
module Cop
module Style
# Checks for the instantiation of array using redundant `Array` constructor.
# Autocorrect replaces to array literal which is the simplest and fastest.
#
# @example
#
# # bad
# Array.new([])
# Array[]
# Array([])
# Array.new(['foo', 'foo', 'foo'])
# Array['foo', 'foo', 'foo']
# Array(['foo', 'foo', 'foo'])
#
# # good
# []
# ['foo', 'foo', 'foo']
# Array.new(3, 'foo')
# Array.new(3) { 'foo' }
#
class RedundantArrayConstructor < Base
extend AutoCorrector
MSG = 'Remove the redundant `Array` constructor.'
RESTRICT_ON_SEND = %i[new [] Array].freeze
# @!method redundant_array_constructor(node)
def_node_matcher :redundant_array_constructor, <<~PATTERN
{
(send
(const {nil? cbase} :Array) :new
$(array ...))
(send
(const {nil? cbase} :Array) :[]
$...)
(send
nil? :Array
$(array ...))
}
PATTERN
def on_send(node)
return unless (array_literal = redundant_array_constructor(node))
receiver = node.receiver
selector = node.loc.selector
if node.method?(:new)
range = receiver.source_range.join(selector)
replacement = array_literal
elsif node.method?(:Array)
range = selector
replacement = array_literal
else
range = receiver
replacement = selector.begin.join(node.source_range.end)
end
register_offense(range, node, replacement)
end
private
def register_offense(range, node, replacement)
add_offense(range) do |corrector|
corrector.replace(node, replacement.source)
end
end
end
end
end
end