class RubbyCop::Cop::Style::TrailingUnderscoreVariable

This cop checks for extra underscores in variable assignment.

@example

# bad
a, b, _ = foo()
a, b, _, = foo()
a, _, _ = foo()
a, _, _, = foo()

# good
a, b, = foo()
a, = foo()
*a, b, _ = foo()  => We need to know to not include 2 variables in a
a, *b, _ = foo()  => The correction `a, *b, = foo()` is a syntax error

# good if AllowNamedUnderscoreVariables is true
a, b, _something = foo()

Constants

MSG
UNDERSCORE

Public Instance Methods

autocorrect(node) click to toggle source
# File lib/rubbycop/cop/style/trailing_underscore_variable.rb, line 42
def autocorrect(node)
  range = unneeded_range(node)

  lambda do |corrector|
    corrector.remove(range) if range
  end
end
on_masgn(node) click to toggle source
# File lib/rubbycop/cop/style/trailing_underscore_variable.rb, line 30
def on_masgn(node)
  range = unneeded_range(node)

  return unless range

  good_code = node.source
  offset = range.begin_pos - node.source_range.begin_pos
  good_code[offset, range.size] = ''

  add_offense(node, range, format(MSG, good_code))
end

Private Instance Methods

allow_named_underscore_variables() click to toggle source
# File lib/rubbycop/cop/style/trailing_underscore_variable.rb, line 87
def allow_named_underscore_variables
  @allow_named_underscore_variables ||=
    cop_config['AllowNamedUnderscoreVariables']
end
find_first_offense(variables) click to toggle source
# File lib/rubbycop/cop/style/trailing_underscore_variable.rb, line 52
def find_first_offense(variables)
  first_offense = find_first_possible_offense(variables.reverse)

  return unless first_offense
  return if splat_variable_before?(first_offense, variables)

  first_offense
end
find_first_possible_offense(variables) click to toggle source
# File lib/rubbycop/cop/style/trailing_underscore_variable.rb, line 61
def find_first_possible_offense(variables)
  variables.reduce(nil) do |offense, variable|
    var, = *variable
    var, = *var
    if allow_named_underscore_variables
      break offense unless var == :_
    else
      break offense unless var.to_s.start_with?(UNDERSCORE)
    end

    variable
  end
end
reverse_index(collection, item) click to toggle source
# File lib/rubbycop/cop/style/trailing_underscore_variable.rb, line 83
def reverse_index(collection, item)
  collection.size - 1 - collection.reverse.index(item)
end
splat_variable_before?(first_offense, variables) click to toggle source
# File lib/rubbycop/cop/style/trailing_underscore_variable.rb, line 75
def splat_variable_before?(first_offense, variables)
  # Account for cases like `_, *rest, _`, where we would otherwise get
  # the index of the first underscore.
  first_offense_index = reverse_index(variables, first_offense)

  variables[0...first_offense_index].any?(&:splat_type?)
end
unneeded_range(node) click to toggle source
# File lib/rubbycop/cop/style/trailing_underscore_variable.rb, line 92
def unneeded_range(node)
  left, right = *node
  variables = *left
  first_offense = find_first_offense(variables)

  return unless first_offense

  end_position =
    if first_offense.source_range == variables.first.source_range
      right.source_range.begin_pos
    else
      node.loc.operator.begin_pos
    end

  range = range_between(first_offense.source_range.begin_pos,
                        end_position)
  range_with_surrounding_space(range, :right)
end