AttributeTranslator optimization (ruby-grape#1944)

Added request_method and requirements has methods instead using method_missing since it's defined by defaults. Added regexp and index in Any class instead of falling back on method_missing

Author: ericproulx

CHANGELOG.md

@@ -3,6 +3,7 @@
 #### Features
 
 * Your contribution here.
+* [#1944](https://github.com/ruby-grape/grape/pull/1944): Reduced attribute_translator string allocations - [@ericproulx](https://github.com/ericproulx).
 * [#1942](https://github.com/ruby-grape/grape/pull/1942): Optimized retained memory methods - [@ericproulx](https://github.com/ericproulx).
 * [#1941](https://github.com/ruby-grape/grape/pull/1941): Frozen string literal - [@ericproulx](https://github.com/ericproulx).
 * [#1940](https://github.com/ruby-grape/grape/pull/1940): Get rid of a needless step in HashWithIndifferentAccess - [@dnesteryuk](https://github.com/dnesteryuk).

lib/grape/router.rb

@@ -7,8 +7,11 @@ class Router
     attr_reader :map, :compiled
 
     class Any < AttributeTranslator
-      def initialize(pattern, **attributes)
+      attr_reader :pattern, :regexp, :index
+      def initialize(pattern, regexp, index, **attributes)
         @pattern = pattern
+        @regexp = regexp
+        @index = index
         super(attributes)
       end
     end
@@ -51,7 +54,7 @@ def append(route)
 
     def associate_routes(pattern, **options)
       regexp = /(?<_#{@neutral_map.length}>)#{pattern.to_regexp}/
-      @neutral_map << Any.new(pattern, regexp: regexp, index: @neutral_map.length, **options)
+      @neutral_map << Any.new(pattern, regexp, @neutral_map.length, **options)
     end
 
     def call(env)

lib/grape/router/attribute_translator.rb

@@ -4,31 +4,39 @@ module Grape
   class Router
     # this could be an OpenStruct, but doesn't work in Ruby 2.3.0, see https://bugs.ruby-lang.org/issues/12251
     class AttributeTranslator
+      attr_reader :attributes, :request_method, :requirements
+
       def initialize(attributes = {})
         @attributes = attributes
+        @request_method = attributes[:request_method]
+        @requirements = attributes[:requirements]
       end
 
       def to_h
-        @attributes
+        attributes
       end
 
-      def method_missing(m, *args)
-        if m[-1] == '='
-          @attributes[m[0..-1]] = *args
-        elsif m[-1] != '='
-          @attributes[m]
+      def method_missing(method_name, *args) # rubocop:disable Style/MethodMissing
+        if setter?(method_name[-1])
+          attributes[method_name[0..-1]] = *args
         else
-          super
+          attributes[method_name]
         end
       end
 
       def respond_to_missing?(method_name, _include_private = false)
-        if method_name[-1] == '='
+        if setter?(method_name[-1])
           true
         else
           @attributes.key?(method_name)
         end
       end
+
+      private
+
+      def setter?(method_name)
+        method_name[-1] == '='
+      end
     end
   end
 end