rafactored the regex related code in the mapper class

actionpack/lib/action_dispatch/routing/mapper.rb

@@ -49,6 +49,9 @@ def constraint_args(constraint, request)
 
       class Mapping #:nodoc:
         IGNORE_OPTIONS = [:to, :as, :via, :on, :constraints, :defaults, :only, :except, :anchor, :shallow, :shallow_path, :shallow_prefix]
+        ANCHOR_CHARACTERS_REGEX = %r{\A(\\A|\^)|(\\Z|\\z|\$)\Z}
+        SHORTHAND_REGEX = %r{^/[\w\/]+$}
+        WILDCARD_PATH = %r{\*([^\/]+)$}
 
         def initialize(set, scope, path, options)
           @set, @scope = set, scope
@@ -77,18 +80,18 @@ def normalize_options!
               # segment_keys.include?(k.to_s) || k == :controller
               next unless Regexp === requirement && !constraints[name]
 
-              if requirement.source =~ %r{\A(\\A|\^)|(\\Z|\\z|\$)\Z}
+              if requirement.source =~ ANCHOR_CHARACTERS_REGEX
                 raise ArgumentError, "Regexp anchor characters are not allowed in routing requirements: #{requirement.inspect}"
               end
               if requirement.multiline?
                 raise ArgumentError, "Regexp multiline option not allowed in routing requirements: #{requirement.inspect}"
               end
             end
-          end
+        end
 
           # match "account/overview"
           def using_match_shorthand?(path, options)
-            path && options.except(:via, :anchor, :to, :as).empty? && path =~ %r{^/[\w\/]+$}
+            path && options.except(:via, :anchor, :to, :as).empty? && path =~ SHORTHAND_REGEX
           end
 
           def normalize_path(path)
@@ -107,7 +110,7 @@ def normalize_path(path)
 
             # Add a constraint for wildcard route to make it non-greedy and match the
             # optional format part of the route by default
-            if path.match(/\*([^\/]+)$/) && @options[:format] != false
+            if path.match(WILDCARD_PATH) && @options[:format] != false
               @options.reverse_merge!(:"#{$1}" => /.+?/)
             end