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# This may be added in the near future to rubocop, see https://github.com/bbatsov/rubocop/issues/5332
module RuboCop
module Cop
module Salsify
# Use `dig` for deeply nested access.
#
# @example
#
# # good
# my_hash.dig('foo', 'bar')
# my_array.dig(0, 1)
#
# # bad
# my_hash['foo']['bar']
# my_hash['foo'] && my_hash['foo']['bar']
# my_array[0][1]
class StyleDig < Cop
extend TargetRubyVersion
minimum_target_ruby_version 2.3
MSG = 'Use `dig` for nested access.'.freeze
def_node_matcher :nested_access_match, <<-PATTERN
(send (send (send _receiver !:[]) :[] !{irange erange}) :[] !{irange erange})
PATTERN
def on_send(node)
return unless nested_access_match(node) && !assignment?(node)
match_node = node
# walk to outermost access node
match_node = match_node.parent while access_node?(match_node.parent)
add_offense(match_node, location: :expression, message: MSG)
end
def autocorrect(node)
access_node = node
source_args = [access_node.first_argument.source]
while access_node?(access_node.children.first)
access_node = access_node.children.first
source_args << access_node.first_argument.source
end
root_node = access_node.children.first
lambda do |corrector|
range = Parser::Source::Range.new(node.source_range.source_buffer,
root_node.source_range.end_pos,
node.source_range.end_pos)
corrector.replace(range, ".dig(#{source_args.reverse.join(', ')})")
end
end
private
def assignment?(node)
node.parent&.assignment? && (node.parent.children.first == node)
end
def access_node?(node)
node&.send_type? && node.method_name == :[] && !range?(node.first_argument)
end
def range?(node)
node.irange_type? || node.erange_type?
end
end
end
end
end