Optimize ripper translator

lib/prism/lex_compat.rb

@@ -667,7 +667,7 @@ def result
 
         event = RIPPER.fetch(token.type)
         value = token.value
-        lex_state = Translation::Ripper::Lexer::State.new(lex_state)
+        lex_state = Translation::Ripper::Lexer::State.cached(lex_state)
 
         token =
           case event
@@ -734,7 +734,7 @@ def result
                   counter += { on_embexpr_beg: -1, on_embexpr_end: 1 }[current_event] || 0
                 end
 
-                Translation::Ripper::Lexer::State.new(result_value[current_index][1])
+                Translation::Ripper::Lexer::State.cached(result_value[current_index][1])
               else
                 previous_state
               end

lib/prism/translation/ripper/lexer.rb

@@ -38,6 +38,13 @@ def |(i) self.class.new(to_int | i) end
           def allbits?(i) to_int.allbits?(i) end
           def anybits?(i) to_int.anybits?(i) end
           def nobits?(i) to_int.nobits?(i) end
+
+          # Instances are frozen and there are only a handful of them so we cache them here.
+          STATES = Hash.new { |h,k| h[k] = State.new(k) }
+
+          def self.cached(i)
+            STATES[i]
+          end
         end
 
         class Elem
@@ -47,7 +54,7 @@ def initialize(pos, event, tok, state, message = nil)
             @pos = pos
             @event = event
             @tok = tok
-            @state = State.new(state)
+            @state = State.cached(state)
             @message = message
           end