Reduce duplication in mutant/constants.rb via class level helper

lib/mutant/constants.rb

@@ -2,30 +2,36 @@
 
 module Mutant
 
+  # Return a frozen set of symbols from string enumerable
+  #
+  # @param [Enumerable<String>]
+  #
+  # @return [Set<Symbol>]
+  #
+  # @api private
+  #
+  def self.symbolset(strings)
+    strings.map(&:to_sym).to_set.freeze
+  end
+  private_class_method :symbolset
+
   # Set of nodes that cannot be on the LHS of an assignment
-  NOT_ASSIGNABLE = [
-    :int, :float, :str, :dstr, :class, :module, :self
-  ].to_set.freeze
+  NOT_ASSIGNABLE = symbolset %w(
+    int float str dstr class module self
+  )
 
   # Set of op-assign types
-  OP_ASSIGN = [
-    :or_asgn, :and_asgn, :op_asgn
-  ].to_set.freeze
-
+  OP_ASSIGN              = symbolset %w(or_asgn and_asgn op_asgn)
   # Set of node types that are not valid when emitted standalone
-  NOT_STANDALONE = [:splat, :restarg, :block_pass].to_set.freeze
+  NOT_STANDALONE         = symbolset %w( splat restarg block_pass)
+  INDEX_OPERATORS        = symbolset %w([] []=)
+  UNARY_METHOD_OPERATORS = symbolset %w(~@ +@ -@ !)
 
   # Operators ruby implementeds as methods
-  METHOD_OPERATORS = %w(
+  METHOD_OPERATORS = symbolset %w(
     <=> === []= [] <= >= == !~ != =~ <<
     >> ** * % /  | ^ & < > + - ~@ +@ -@ !
-  ).map(&:to_sym).to_set.freeze
-
-  INDEX_OPERATORS = [:[], :[]=].to_set.freeze
-
-  UNARY_METHOD_OPERATORS = %w(
-    ~@ +@ -@ !
-  ).map(&:to_sym).to_set.freeze
+  )
 
   BINARY_METHOD_OPERATORS = (
     METHOD_OPERATORS - (INDEX_OPERATORS + UNARY_METHOD_OPERATORS)
@@ -39,14 +45,10 @@ module Mutant
   #
   # not - 1.8 only, mutant does not support 1.8
   #
-  NODE_BLACKLIST = %w(
-    not
-  ).map(&:to_sym).freeze
+  NODE_BLACKLIST = symbolset %w(not)
 
   # Nodes that are NOT generated by parser but used by mutant / unparser.
-  NODE_EXTRA = %w(
-    empty
-  ).map(&:to_sym).freeze
+  NODE_EXTRA = symbolset %w(empty)
 
   NODE_TYPES = ((Parser::Meta::NODE_TYPES + NODE_EXTRA) - NODE_BLACKLIST).to_set.freeze
 

lib/parser-node-list.rb

@@ -22,4 +22,3 @@ module Parser
       ).map(&:to_sym).to_set.freeze
   end # Meta
 end # Parser
-