Class: RuboCop::Cop::Style::TrailingUnderscoreVariable

# File 'lib/rubocop/cop/style/trailing_underscore_variable.rb', line 127

def children_offenses(variables)
  variables.select(&:mlhs_type?).flat_map { |v| unneeded_ranges(v) }
end

# File 'lib/rubocop/cop/style/trailing_underscore_variable.rb', line 58

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

# File 'lib/rubocop/cop/style/trailing_underscore_variable.rb', line 67

def find_first_possible_offense(variables)
  variables.reduce(nil) do |offense, variable|
    break offense unless DISALLOW.include?(variable.type)

    var, = *variable
    var, = *var

    break offense if (allow_named_underscore_variables && var != :_) ||
                     !var.to_s.start_with?(UNDERSCORE)

    variable
  end
end

# File 'lib/rubocop/cop/style/trailing_underscore_variable.rb', line 109

def main_node_offense(node)
  mlhs_node = node.masgn_type? ? node.lhs : node
  variables = *mlhs_node

  first_offense = find_first_offense(variables)

  return unless first_offense

  return unused_range(node, mlhs_node) if unused_variables_only?(first_offense, variables)

  range = if Util.parentheses?(mlhs_node)
            range_for_parentheses(first_offense, mlhs_node)
          else
            range_between(first_offense.source_range.begin_pos, node.loc.operator.begin_pos)
          end
  [range, '']
end

# File 'lib/rubocop/cop/style/trailing_underscore_variable.rb', line 42

def on_masgn(node)
  unneeded_ranges(node).each do |range, replacement|
    closing = replacement == ARRAY_OPENING ? ']' : ''
    good_code = node.source
    offset = range.begin_pos - node.source_range.begin_pos
    good_code[offset, range.size] = replacement

    add_offense(range, message: format(MSG, code: "#{good_code}#{closing}")) do |corrector|
      corrector.replace(range, replacement)
      corrector.insert_after(node, closing) unless closing.empty?
    end
  end
end

# File 'lib/rubocop/cop/style/trailing_underscore_variable.rb', line 149

def range_for_parentheses(offense, left)
  range_between(offense.source_range.begin_pos - 1, left.source_range.end_pos - 1)
end

# File 'lib/rubocop/cop/style/trailing_underscore_variable.rb', line 89

def reverse_index(collection, item)
  collection.size - 1 - collection.reverse.index(item)
end

# File 'lib/rubocop/cop/style/trailing_underscore_variable.rb', line 81

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

# File 'lib/rubocop/cop/style/trailing_underscore_variable.rb', line 97

def unneeded_ranges(node)
  mlhs_node = node.masgn_type? ? node.lhs : node
  variables = *mlhs_node

  main_offense = main_node_offense(node)
  if main_offense.nil?
    children_offenses(variables)
  else
    children_offenses(variables) << main_offense
  end
end

# File 'lib/rubocop/cop/style/trailing_underscore_variable.rb', line 135

def unused_range(node, mlhs_node)
  # `node` can be an `mlhs` when recursing into a nested destructuring
  # group. Removing the group could leave a dangling comma or put
  # something after a splat, so it is collapsed into a single `_`,
  # which the parent group handles in turn.
  return [mlhs_node.source_range, UNDERSCORE] unless node.masgn_type?

  rhs = node.rhs
  range = range_between(mlhs_node.source_range.begin_pos, rhs.source_range.begin_pos)

  # `_, _ = 1, 2` cannot become `1, 2`, so the values become an array literal.
  [range, rhs.array_type? && !rhs.bracketed? ? ARRAY_OPENING : '']
end

# File 'lib/rubocop/cop/style/trailing_underscore_variable.rb', line 131

def unused_variables_only?(offense, variables)
  offense.source_range == variables.first.source_range
end