Replace each_slice by a while loop

Unfortunately `each_slice` performs pretty poorly because
it isn't specialized for `Array`.

Author: byroot

actionpack/lib/action_dispatch/journey/gtg/simulator.rb

@@ -51,8 +51,16 @@ def memos(string)
           end
 
           acceptance_states = []
-          state.each_slice(2) do |s, idx|
-            acceptance_states.concat(tt.memo(s)) if idx.nil? && tt.accepting?(s)
+          states_count = state.size
+          i = 0
+          while i < states_count
+            if state[i + 1].nil?
+              s = state[i]
+              if tt.accepting?(s)
+                acceptance_states.concat(tt.memo(s))
+              end
+            end
+            i += 2
           end
 
           acceptance_states.empty? ? yield : acceptance_states

actionpack/lib/action_dispatch/journey/gtg/transition_table.rb

@@ -52,7 +52,11 @@ def move(t, full_string, token, start_index, token_matches_default)
 
           next_states = []
 
-          t.each_slice(2) { |s, previous_start|
+          transitions_count = t.size
+          i = 0
+          while i < transitions_count
+            s = t[i]
+            previous_start = t[i + 1]
             if previous_start.nil?
               # In the simple case of a "default" param regex do this fast-path and add all
               # next states.
@@ -90,7 +94,9 @@ def move(t, full_string, token, start_index, token_matches_default)
               # need to remember where we started as well so we can take bigger slices.
               next_states << s << slice_start
             end
-          }
+
+            i += 2
+          end
 
           next_states
         end