class RuboCop::Cop::Style::SingleLineBlockParams

This cop checks whether the block parameters of a single-line method accepting a block match the names specified via configuration.

For instance one can configure `reduce`(`inject`) to use |a, e| as parameters.

Configuration option: Methods Should be set to use this cop. Array of hashes, where each key is the method name and value - array of argument names.

@example Methods: [{reduce: %w[a b]}]

# bad
foo.reduce { |c, d| c + d }
foo.reduce { |_, _d| 1 }

# good
foo.reduce { |a, b| a + b }
foo.reduce { |a, _b| a }
foo.reduce { |a, (id, _)| a + id }
foo.reduce { true }

# good
foo.reduce do |c, d|
  c + d
end

Constants

MSG

Public Instance Methods

on_block(node) click to toggle source
# File lib/rubocop/cop/style/single_line_block_params.rb, line 34
def on_block(node)
  return unless node.single_line?

  return unless eligible_method?(node)
  return unless eligible_arguments?(node)

  return if args_match?(node.send_node.method_name, node.arguments)

  add_offense(node.arguments)
end

Private Instance Methods

args_match?(method_name, args) click to toggle source
# File lib/rubocop/cop/style/single_line_block_params.rb, line 81
def args_match?(method_name, args)
  actual_args = args.to_a.flat_map(&:to_a)

  # Prepending an underscore to mark an unused parameter is allowed, so
  # we remove any leading underscores before comparing.
  actual_args_no_underscores = actual_args.map do |arg|
    arg.to_s.sub(/^_+/, '')
  end

  actual_args_no_underscores == target_args(method_name)
end
eligible_arguments?(node) click to toggle source
# File lib/rubocop/cop/style/single_line_block_params.rb, line 54
def eligible_arguments?(node)
  node.arguments? && node.arguments.to_a.all?(&:arg_type?)
end
eligible_method?(node) click to toggle source
# File lib/rubocop/cop/style/single_line_block_params.rb, line 58
def eligible_method?(node)
  node.send_node.receiver &&
    method_names.include?(node.send_node.method_name)
end
message(node) click to toggle source
# File lib/rubocop/cop/style/single_line_block_params.rb, line 47
def message(node)
  method_name = node.parent.send_node.method_name
  arguments   = target_args(method_name).join(', ')

  format(MSG, method: method_name, params: arguments)
end
method_name(method) click to toggle source
# File lib/rubocop/cop/style/single_line_block_params.rb, line 71
def method_name(method)
  method.keys.first
end
method_names() click to toggle source
# File lib/rubocop/cop/style/single_line_block_params.rb, line 67
def method_names
  methods.map { |method| method_name(method).to_sym }
end
methods() click to toggle source
# File lib/rubocop/cop/style/single_line_block_params.rb, line 63
def methods
  cop_config['Methods']
end
target_args(method_name) click to toggle source
# File lib/rubocop/cop/style/single_line_block_params.rb, line 75
def target_args(method_name)
  method_name = method_name.to_s
  method_hash = methods.find { |m| method_name(m) == method_name }
  method_hash[method_name]
end