class RuboCop::Cop::Style::RedundantParentheses

Checks for redundant parentheses.

@example

# bad
(x) if ((y.z).nil?)

# good
x if y.z.nil?

Constants

ALLOWED_NODE_TYPES

Public Instance Methods

on_begin(node) click to toggle source
# File lib/rubocop/cop/style/redundant_parentheses.rb, line 34
def on_begin(node)
  return if !parentheses?(node) || parens_allowed?(node) || ignore_syntax?(node)

  check(node)
end

Private Instance Methods

allow_in_multiline_conditions?() click to toggle source
# File lib/rubocop/cop/style/redundant_parentheses.rb, line 168
def allow_in_multiline_conditions?
  parentheses_around_condition_config = config.for_cop('Style/ParenthesesAroundCondition')
  return false unless parentheses_around_condition_config['Enabled']

  !!parentheses_around_condition_config['AllowInMultilineConditions']
end
allowed_ancestor?(node) click to toggle source
# File lib/rubocop/cop/style/redundant_parentheses.rb, line 64
def allowed_ancestor?(node)
  # Don't flag `break(1)`, etc
  keyword_ancestor?(node) && parens_required?(node)
end
allowed_expression?(node) click to toggle source
# File lib/rubocop/cop/style/redundant_parentheses.rb, line 57
def allowed_expression?(node)
  allowed_ancestor?(node) ||
    allowed_multiple_expression?(node) ||
    allowed_ternary?(node) ||
    node.parent&.range_type?
end
allowed_multiple_expression?(node) click to toggle source
# File lib/rubocop/cop/style/redundant_parentheses.rb, line 69
def allowed_multiple_expression?(node)
  return false if node.children.one?

  ancestor = node.ancestors.first
  return false unless ancestor

  !ancestor.begin_type? && !ancestor.def_type? && !ancestor.block_type?
end
allowed_ternary?(node) click to toggle source
# File lib/rubocop/cop/style/redundant_parentheses.rb, line 78
def allowed_ternary?(node)
  return false unless node&.parent&.if_type?

  node.parent.ternary? && ternary_parentheses_required?
end
call_chain_starts_with_int?(begin_node, send_node) click to toggle source
# File lib/rubocop/cop/style/redundant_parentheses.rb, line 275
def call_chain_starts_with_int?(begin_node, send_node)
  recv = first_part_of_call_chain(send_node)
  recv&.int_type? && (parent = begin_node.parent) &&
    parent.send_type? && (parent.method?(:-@) || parent.method?(:+@))
end
check(begin_node) click to toggle source
# File lib/rubocop/cop/style/redundant_parentheses.rb, line 127
def check(begin_node)
  node = begin_node.children.first

  if (message = find_offense_message(begin_node, node))
    return offense(begin_node, message)
  end

  check_send(begin_node, node) if node.call_type?
end
check_send(begin_node, node) click to toggle source
# File lib/rubocop/cop/style/redundant_parentheses.rb, line 175
def check_send(begin_node, node)
  return check_unary(begin_node, node) if node.unary_operation?

  return unless method_call_with_redundant_parentheses?(node)
  return if call_chain_starts_with_int?(begin_node, node) ||
            do_end_block_in_method_chain?(begin_node, node)

  offense(begin_node, 'a method call')
end
check_unary(begin_node, node) click to toggle source
# File lib/rubocop/cop/style/redundant_parentheses.rb, line 185
def check_unary(begin_node, node)
  return if begin_node.chained?

  node = node.children.first while suspect_unary?(node)

  return if node.send_type? && !method_call_with_redundant_parentheses?(node)

  offense(begin_node, 'a unary operation')
end
disallowed_literal?(begin_node, node) click to toggle source
# File lib/rubocop/cop/style/redundant_parentheses.rb, line 209
def disallowed_literal?(begin_node, node)
  node.literal? && !node.range_type? && !raised_to_power_negative_numeric?(begin_node, node)
end
do_end_block_in_method_chain?(begin_node, node) click to toggle source
# File lib/rubocop/cop/style/redundant_parentheses.rb, line 281
def do_end_block_in_method_chain?(begin_node, node)
  return false unless (block = node.each_descendant(:block, :numblock).first)

  block.keywords? && begin_node.each_ancestor(:send, :csend).any?
end
empty_parentheses?(node) click to toggle source
# File lib/rubocop/cop/style/redundant_parentheses.rb, line 105
def empty_parentheses?(node)
  # Don't flag `()`
  node.children.empty?
end
find_offense_message(begin_node, node) click to toggle source

rubocop:disable Metrics/AbcSize, Metrics/CyclomaticComplexity, Metrics/MethodLength, Metrics/PerceivedComplexity

# File lib/rubocop/cop/style/redundant_parentheses.rb, line 138
def find_offense_message(begin_node, node)
  return 'a keyword' if keyword_with_redundant_parentheses?(node)
  return 'a literal' if disallowed_literal?(begin_node, node)
  return 'a variable' if node.variable?
  return 'a constant' if node.const_type?
  if node.lambda_or_proc? && (node.braces? || node.send_node.lambda_literal?)
    return 'an expression'
  end
  return 'an interpolated expression' if interpolation?(begin_node)

  return if begin_node.chained?

  if node.and_type? || node.or_type?
    return if node.semantic_operator? && begin_node.parent
    return if node.multiline? && allow_in_multiline_conditions?
    return if ALLOWED_NODE_TYPES.include?(begin_node.parent&.type)
    return if begin_node.parent&.if_type? && begin_node.parent.ternary?

    'a logical expression'
  elsif node.respond_to?(:comparison_method?) && node.comparison_method?
    return unless begin_node.parent.nil?

    'a comparison expression'
  end
end
first_arg_begins_with_hash_literal?(node) click to toggle source
# File lib/rubocop/cop/style/redundant_parentheses.rb, line 110
def first_arg_begins_with_hash_literal?(node)
  # Don't flag `method ({key: value})` or `method ({key: value}.method)`
  hash_literal = method_chain_begins_with_hash_literal(node.children.first)
  if (root_method = node.each_ancestor(:send).to_a.last)
    parenthesized = root_method.parenthesized_call?
  end
  hash_literal && first_argument?(node) && !parentheses?(hash_literal) && !parenthesized
end
first_argument?(node) click to toggle source
# File lib/rubocop/cop/style/redundant_parentheses.rb, line 250
def first_argument?(node)
  if first_send_argument?(node) ||
     first_super_argument?(node) ||
     first_yield_argument?(node)
    return true
  end

  node.each_ancestor.any? { |ancestor| first_argument?(ancestor) }
end
ignore_syntax?(node) click to toggle source
# File lib/rubocop/cop/style/redundant_parentheses.rb, line 50
def ignore_syntax?(node)
  return false unless (parent = node.parent)

  parent.while_post_type? || parent.until_post_type? || parent.match_with_lvasgn_type? ||
    like_method_argument_parentheses?(parent) || multiline_control_flow_statements?(node)
end
keyword_ancestor?(node) click to toggle source
# File lib/rubocop/cop/style/redundant_parentheses.rb, line 205
def keyword_ancestor?(node)
  node.parent&.keyword?
end
keyword_with_redundant_parentheses?(node) click to toggle source
# File lib/rubocop/cop/style/redundant_parentheses.rb, line 224
def keyword_with_redundant_parentheses?(node)
  return false unless node.keyword?
  return true if node.special_keyword?

  args = *node

  if only_begin_arg?(args)
    parentheses?(args.first)
  else
    args.empty? || parentheses?(node)
  end
end
like_method_argument_parentheses?(node) click to toggle source
# File lib/rubocop/cop/style/redundant_parentheses.rb, line 91
def like_method_argument_parentheses?(node)
  return false if !node.send_type? && !node.super_type? && !node.yield_type?

  node.arguments.one? && !node.parenthesized? &&
    !node.arithmetic_operation? && node.first_argument.begin_type?
end
method_call_with_redundant_parentheses?(node) click to toggle source
# File lib/rubocop/cop/style/redundant_parentheses.rb, line 237
def method_call_with_redundant_parentheses?(node)
  return false unless node.call_type?
  return false if node.prefix_not?

  send_node, args = method_node_and_args(node)

  args.empty? || parentheses?(send_node) || square_brackets?(send_node)
end
method_chain_begins_with_hash_literal(node) click to toggle source
# File lib/rubocop/cop/style/redundant_parentheses.rb, line 119
def method_chain_begins_with_hash_literal(node)
  return if node.nil?
  return node if node.hash_type?
  return unless node.send_type?

  method_chain_begins_with_hash_literal(node.children.first)
end
multiline_control_flow_statements?(node) click to toggle source
# File lib/rubocop/cop/style/redundant_parentheses.rb, line 98
def multiline_control_flow_statements?(node)
  return false unless (parent = node.parent)
  return false if parent.single_line?

  parent.return_type? || parent.next_type? || parent.break_type?
end
offense(node, msg) click to toggle source
# File lib/rubocop/cop/style/redundant_parentheses.rb, line 195
def offense(node, msg)
  add_offense(node, message: "Don't use parentheses around #{msg}.") do |corrector|
    ParenthesesCorrector.correct(corrector, node)
  end
end
only_begin_arg?(args) click to toggle source
# File lib/rubocop/cop/style/redundant_parentheses.rb, line 246
def only_begin_arg?(args)
  args.one? && args.first.begin_type?
end
parens_allowed?(node) click to toggle source
# File lib/rubocop/cop/style/redundant_parentheses.rb, line 42
def parens_allowed?(node)
  empty_parentheses?(node) ||
    first_arg_begins_with_hash_literal?(node) ||
    rescue?(node) ||
    allowed_pin_operator?(node) ||
    allowed_expression?(node)
end
raised_to_power_negative_numeric?(begin_node, node) click to toggle source
# File lib/rubocop/cop/style/redundant_parentheses.rb, line 213
def raised_to_power_negative_numeric?(begin_node, node)
  return false unless node.numeric_type?

  next_sibling = begin_node.right_sibling
  return false unless next_sibling

  base_value = node.children.first

  base_value.negative? && next_sibling == :**
end
suspect_unary?(node) click to toggle source
# File lib/rubocop/cop/style/redundant_parentheses.rb, line 201
def suspect_unary?(node)
  node.send_type? && node.unary_operation? && !node.prefix_not?
end
ternary_parentheses_required?() click to toggle source
# File lib/rubocop/cop/style/redundant_parentheses.rb, line 84
def ternary_parentheses_required?
  config = @config.for_cop('Style/TernaryParentheses')
  allowed_styles = %w[require_parentheses require_parentheses_when_complex]

  config.fetch('Enabled') && allowed_styles.include?(config['EnforcedStyle'])
end