Class: RuboCop::Cop::Style::SymbolProc

Inherits:
Cop
  • Object
show all
Defined in:
lib/rubocop/cop/style/symbol_proc.rb

Overview

Use symbols as procs when possible.

Examples:

# bad
something.map { |s| s.upcase }

# good
something.map(&:upcase)

Constant Summary collapse

MSG =
'Pass `&:%s` as an argument to `%s` instead of a block.'

Constants included from Util

Util::ASGN_NODES, Util::EQUALS_ASGN_NODES, Util::OPERATOR_METHODS, Util::PROC_NEW_NODE, Util::SHORTHAND_ASGN_NODES

Instance Attribute Summary

Attributes inherited from Cop

#config, #corrections, #offenses, #processed_source

Instance Method Summary collapse

Methods inherited from Cop

#add_offense, all, #autocorrect?, #config_to_allow_offenses, #config_to_allow_offenses=, #cop_config, cop_name, #cop_name, cop_name_with_namespace, cop_type, #debug?, #display_cop_names?, inherited, #initialize, #join_force?, lint?, #message, non_rails, qualified_cop_name, rails?, #relevant_file?, #support_autocorrect?

Methods included from IgnoredNode

#ignore_node, #ignored_node?, #part_of_ignored_node?

Methods included from Util

begins_its_line?, block_length, command?, comment_line?, const_name, first_part_of_call_chain, lambda?, lambda_or_proc?, line_range, numeric_range_size, on_node, operator?, parentheses?, proc?, range_with_surrounding_space, source_range, strip_quotes, within_node?

Methods included from PathUtil

issue_deprecation_warning, match_path?, relative_path

Constructor Details

This class inherits a constructor from RuboCop::Cop::Cop

Instance Method Details

#autocorrect(node) ⇒ Object


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# File 'lib/rubocop/cop/style/symbol_proc.rb', line 37

def autocorrect(node)
  @corrections << lambda do |corrector|
    block_method, _block_args, block_body = *node
    _receiver, method_name, _args = *block_body

    replacement = "#{block_method.loc.expression.source}" \
                  "(&:#{method_name})"

    corrector.replace(node.loc.expression, replacement)
  end
end

#can_shorten?(block_args, block_body) ⇒ Boolean

Returns:

  • (Boolean)

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# File 'lib/rubocop/cop/style/symbol_proc.rb', line 57

def can_shorten?(block_args, block_body)
  # something { |x, y| ... }
  return false unless block_args.children.size == 1
  return false unless block_body && block_body.type == :send

  receiver, _method_name, args = *block_body

  # method in block must be invoked on a lvar without args
  return false if args
  return false unless receiver && receiver.type == :lvar

  block_arg_name, = *block_args.children.first
  receiver_name, = *receiver

  block_arg_name == receiver_name
end

#ignored_method?(name) ⇒ Boolean

Returns:

  • (Boolean)

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# File 'lib/rubocop/cop/style/symbol_proc.rb', line 53

def ignored_method?(name)
  ignored_methods.include?(name.to_s)
end

#ignored_methodsObject


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# File 'lib/rubocop/cop/style/symbol_proc.rb', line 49

def ignored_methods
  cop_config['IgnoredMethods']
end

#on_block(node) ⇒ Object


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# File 'lib/rubocop/cop/style/symbol_proc.rb', line 17

def on_block(node)
  block_send, block_args, block_body = *node

  _breceiver, bmethod_name, bargs = *block_send

  # we should ignore lambdas
  return if bmethod_name == :lambda
  return if ignored_method?(bmethod_name)
  # File.open(file) { |f| f.readlines }
  return if bargs
  return unless can_shorten?(block_args, block_body)

  _receiver, method_name, _args = *block_body
  add_offense(node,
              :expression,
              format(MSG,
                     method_name,
                     bmethod_name))
end