class RuboCop::Cop::Style::EachWithObject

This cop looks for inject / reduce calls where the passed in object is returned at the end and so could be replaced by each_with_object without the need to return the object at the end.

However, we can't replace with each_with_object if the accumulator parameter is assigned to within the block.

@example

# bad
[1, 2].inject({}) { |a, e| a[e] = e; a }

# good
[1, 2].each_with_object({}) { |e, a| a[e] = e }

Constants

METHODS
MSG

Public Instance Methods

on_block(node) click to toggle source
# File lib/rubocop/cop/style/each_with_object.rb, line 27
def on_block(node)
  each_with_object_candidate?(node) do |method, args, body|
    _, method_name, method_arg = *method
    return if simple_method_arg?(method_arg)

    return_value = return_value(body)
    return unless return_value
    return unless first_argument_returned?(args, return_value)
    return if accumulator_param_assigned_to?(body, args)

    add_offense(node, location: method.loc.selector,
                      message: format(MSG, method_name))
  end
end

Private Instance Methods

accumulator_param_assigned_to?(body, args) click to toggle source

if the accumulator parameter is assigned to in the block, then we can't convert to each_with_object

# File lib/rubocop/cop/style/each_with_object.rb, line 67
def accumulator_param_assigned_to?(body, args)
  first_arg, = *args
  accumulator_var, = *first_arg

  body.each_descendant.any? do |n|
    next unless n.assignment?

    lhs, _rhs = *n
    lhs.equal?(accumulator_var)
  end
end
autocorrect(node) click to toggle source

rubocop:disable Metrics/AbcSize

# File lib/rubocop/cop/style/each_with_object.rb, line 45
def autocorrect(node)
  lambda do |corrector|
    corrector.replace(node.send_node.loc.selector, 'each_with_object')

    first_arg, second_arg = *node.arguments

    corrector.replace(first_arg.loc.expression, second_arg.source)
    corrector.replace(second_arg.loc.expression, first_arg.source)

    return_value = return_value(node.body)

    corrector.remove(return_value.loc.expression)
  end
end
first_argument_returned?(args, return_value) click to toggle source
# File lib/rubocop/cop/style/each_with_object.rb, line 86
def first_argument_returned?(args, return_value)
  first_arg, = *args
  accumulator_var, = *first_arg
  return_var, = *return_value

  accumulator_var == return_var
end
return_value(body) click to toggle source
# File lib/rubocop/cop/style/each_with_object.rb, line 79
def return_value(body)
  return unless body

  return_value = body.begin_type? ? body.children.last : body
  return_value if return_value && return_value.lvar_type?
end
simple_method_arg?(method_arg) click to toggle source

rubocop:endable Metrics/AbcSize

# File lib/rubocop/cop/style/each_with_object.rb, line 61
def simple_method_arg?(method_arg)
  method_arg && method_arg.basic_literal?
end