[fixes rubocop#22] Introduce List, a frozen Array/Set

Author: marcandre

lib/rubocop/ast.rb

@@ -3,6 +3,7 @@
 require 'parser'
 require 'forwardable'
 
+require_relative 'ast/list'
 require_relative 'ast/node_pattern'
 require_relative 'ast/sexp'
 require_relative 'ast/node'

lib/rubocop/ast/list.rb

@@ -0,0 +1,28 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module AST
+    # A frozen Array/Set
+    #
+    class List < ::Array
+      extend Forwardable
+      attr_reader :to_set
+
+      def initialize(*)
+        super
+        freeze
+      end
+
+      def freeze
+        @to_set = Set.new(self).freeze
+        super
+      end
+
+      def_delegators :@to_set, :include?, :===
+    end
+  end
+end
+
+def List(list)
+  RuboCop::AST::List.new(list)
+end

lib/rubocop/ast/node.rb

@@ -23,37 +23,37 @@ class Node < Parser::AST::Node # rubocop:disable Metrics/ClassLength
       extend NodePattern::Macros
 
       # <=> isn't included here, because it doesn't return a boolean.
-      COMPARISON_OPERATORS = %i[== === != <= >= > <].freeze
+      COMPARISON_OPERATORS = List %i[== === != <= >= > <]
 
-      TRUTHY_LITERALS = %i[str dstr xstr int float sym dsym array
+      TRUTHY_LITERALS = List %i[str dstr xstr int float sym dsym array
                            hash regexp true irange erange complex
-                           rational regopt].freeze
-      FALSEY_LITERALS = %i[false nil].freeze
-      LITERALS = (TRUTHY_LITERALS + FALSEY_LITERALS).freeze
-      COMPOSITE_LITERALS = %i[dstr xstr dsym array hash irange
-                              erange regexp].freeze
-      BASIC_LITERALS = (LITERALS - COMPOSITE_LITERALS).freeze
-      MUTABLE_LITERALS = %i[str dstr xstr array hash
-                            regexp irange erange].freeze
-      IMMUTABLE_LITERALS = (LITERALS - MUTABLE_LITERALS).freeze
-
-      EQUALS_ASSIGNMENTS = %i[lvasgn ivasgn cvasgn gvasgn
-                              casgn masgn].freeze
-      SHORTHAND_ASSIGNMENTS = %i[op_asgn or_asgn and_asgn].freeze
-      ASSIGNMENTS = (EQUALS_ASSIGNMENTS + SHORTHAND_ASSIGNMENTS).freeze
-
-      BASIC_CONDITIONALS = %i[if while until].freeze
-      CONDITIONALS = [*BASIC_CONDITIONALS, :case].freeze
-      VARIABLES = %i[ivar gvar cvar lvar].freeze
-      REFERENCES = %i[nth_ref back_ref].freeze
-      KEYWORDS = %i[alias and break case class def defs defined?
+                           rational regopt]
+      FALSEY_LITERALS = List %i[false nil]
+      LITERALS = List(TRUTHY_LITERALS + FALSEY_LITERALS)
+      COMPOSITE_LITERALS = List %i[dstr xstr dsym array hash irange
+                              erange regexp]
+      BASIC_LITERALS = List(LITERALS - COMPOSITE_LITERALS)
+      MUTABLE_LITERALS = List %i[str dstr xstr array hash
+                            regexp irange erange]
+      IMMUTABLE_LITERALS = List (LITERALS - MUTABLE_LITERALS)
+
+      EQUALS_ASSIGNMENTS = List %i[lvasgn ivasgn cvasgn gvasgn
+                              casgn masgn]
+      SHORTHAND_ASSIGNMENTS = List %i[op_asgn or_asgn and_asgn]
+      ASSIGNMENTS = List(EQUALS_ASSIGNMENTS + SHORTHAND_ASSIGNMENTS)
+
+      BASIC_CONDITIONALS = List %i[if while until]
+      CONDITIONALS = List[*BASIC_CONDITIONALS, :case]
+      VARIABLES = List %i[ivar gvar cvar lvar]
+      REFERENCES = List %i[nth_ref back_ref]
+      KEYWORDS = List %i[alias and break case class def defs defined?
                     kwbegin do else ensure for if module next
                     not or postexe redo rescue retry return self
                     super zsuper then undef until when while
-                    yield].freeze
-      OPERATOR_KEYWORDS = %i[and or].freeze
-      SPECIAL_KEYWORDS = %w[__FILE__ __LINE__ __ENCODING__].freeze
-      ARGUMENT_TYPES = %i[arg optarg restarg kwarg kwoptarg kwrestarg blockarg].freeze
+                    yield]
+      OPERATOR_KEYWORDS = List %i[and or]
+      SPECIAL_KEYWORDS = List %w[__FILE__ __LINE__ __ENCODING__]
+      ARGUMENT_TYPES = List %i[arg optarg restarg kwarg kwoptarg kwrestarg blockarg]
 
       # @see https://www.rubydoc.info/gems/ast/AST/Node:initialize
       def initialize(type, children = [], properties = {})

lib/rubocop/ast/node/block_node.rb

@@ -11,7 +11,7 @@ module AST
     class BlockNode < Node
       include MethodIdentifierPredicates
 
-      VOID_CONTEXT_METHODS = %i[each tap].freeze
+      VOID_CONTEXT_METHODS = List %i[each tap]
 
       # The `send` node associated with this block.
       #

lib/rubocop/ast/node/mixin/collection_node.rb

@@ -7,7 +7,7 @@ module CollectionNode
       extend Forwardable
 
       ARRAY_METHODS =
-        (Array.instance_methods - Object.instance_methods - [:to_a]).freeze
+        List(Array.instance_methods - Object.instance_methods - [:to_a])
 
       def_delegators :to_a, *ARRAY_METHODS
     end

lib/rubocop/ast/node/mixin/method_dispatch_node.rb

@@ -8,8 +8,8 @@ module MethodDispatchNode
       extend NodePattern::Macros
       include MethodIdentifierPredicates
 
-      ARITHMETIC_OPERATORS = %i[+ - * / % **].freeze
-      SPECIAL_MODIFIERS = %w[private protected].freeze
+      ARITHMETIC_OPERATORS = List %i[+ - * / % **]
+      SPECIAL_MODIFIERS = List %w[private protected]
 
       # The receiving node of the method dispatch.
       #

lib/rubocop/ast/node/mixin/method_identifier_predicates.rb

@@ -7,14 +7,14 @@ module AST
     #
     # @note this mixin expects `#method_name` and `#receiver` to be implemented
     module MethodIdentifierPredicates
-      ENUMERATOR_METHODS = %i[collect collect_concat detect downto each
+      ENUMERATOR_METHODS = List %i[collect collect_concat detect downto each
                               find find_all find_index inject loop map!
                               map reduce reject reject! reverse_each select
-                              select! times upto].freeze
+                              select! times upto]
 
       # http://phrogz.net/programmingruby/language.html#table_18.4
-      OPERATOR_METHODS = %i[| ^ & <=> == === =~ > >= < <= << >> + - * /
-                            % ** ~ +@ -@ !@ ~@ [] []= ! != !~ `].freeze
+      OPERATOR_METHODS = List %i[| ^ & <=> == === =~ > >= < <= << >> + - * /
+                            % ** ~ +@ -@ !@ ~@ [] []= ! != !~ `]
 
       # Checks whether the method name matches the argument.
       #

lib/rubocop/ast/traversal.rb

@@ -15,27 +15,27 @@ def walk(node)
         nil
       end
 
-      NO_CHILD_NODES    = %i[true false nil int float complex
+      NO_CHILD_NODES    = List %i[true false nil int float complex
                              rational str sym regopt self lvar
                              ivar cvar gvar nth_ref back_ref cbase
                              arg restarg blockarg shadowarg
                              kwrestarg zsuper lambda redo retry
                              forward_args forwarded_args
-                             match_var match_nil_pattern empty_else].freeze
-      ONE_CHILD_NODE    = %i[splat kwsplat block_pass not break next
+                             match_var match_nil_pattern empty_else]
+      ONE_CHILD_NODE    = List %i[splat kwsplat block_pass not break next
                              preexe postexe match_current_line defined?
                              arg_expr pin match_rest if_guard unless_guard
-                             match_with_trailing_comma].freeze
-      MANY_CHILD_NODES  = %i[dstr dsym xstr regexp array hash pair
+                             match_with_trailing_comma]
+      MANY_CHILD_NODES  = List %i[dstr dsym xstr regexp array hash pair
                              mlhs masgn or_asgn and_asgn
                              undef alias args super yield or and
                              while_post until_post iflipflop eflipflop
                              match_with_lvasgn begin kwbegin return
                              in_match match_alt
                              match_as array_pattern array_pattern_with_tail
-                             hash_pattern const_pattern].freeze
-      SECOND_CHILD_ONLY = %i[lvasgn ivasgn cvasgn gvasgn optarg kwarg
-                             kwoptarg].freeze
+                             hash_pattern const_pattern]
+      SECOND_CHILD_ONLY = List %i[lvasgn ivasgn cvasgn gvasgn optarg kwarg
+                             kwoptarg]
 
       NO_CHILD_NODES.each do |type|
         module_eval("def on_#{type}(node); end", __FILE__, __LINE__)