Another array allocation reduction

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 #### Features
 * Your contribution here.
+* [#2020](https://github.com/ruby-grape/grape/pull/2020): Reduce array allocation - [@ericproulx](https://github.com/ericproulx).
 * [#2015](https://github.com/ruby-grape/grape/pull/2014): Reduce MatchData allocation - [@ericproulx](https://github.com/ericproulx).
 * [#2014](https://github.com/ruby-grape/grape/pull/2014): Reduce total allocated arrays - [@ericproulx](https://github.com/ericproulx).
 * [#2011](https://github.com/ruby-grape/grape/pull/2011): Reduce total retained regexes - [@ericproulx](https://github.com/ericproulx).

lib/grape/api/instance.rb

@@ -243,9 +243,13 @@ def add_head_not_allowed_methods_and_options_methods
       # Generate a route that returns an HTTP 405 response for a user defined
       # path on methods not specified
       def generate_not_allowed_method(pattern, allowed_methods: [], **attributes)
-        not_allowed_methods = %w[GET PUT POST DELETE PATCH HEAD] - allowed_methods
-        not_allowed_methods << Grape::Http::Headers::OPTIONS if self.class.namespace_inheritable(:do_not_route_options)
-
+        supported_methods =
+          if self.class.namespace_inheritable(:do_not_route_options)
+            Grape::Http::Headers::SUPPORTED_METHODS
+          else
+            Grape::Http::Headers::SUPPORTED_METHODS_WITHOUT_OPTIONS
+          end
+        not_allowed_methods = supported_methods - allowed_methods
         return if not_allowed_methods.empty?
 
         @router.associate_routes(pattern, not_allowed_methods: not_allowed_methods, **attributes)

lib/grape/http/headers.rb

@@ -21,6 +21,7 @@ module Headers
       OPTIONS = 'OPTIONS'
 
       SUPPORTED_METHODS = [GET, POST, PUT, PATCH, DELETE, HEAD, OPTIONS].freeze
+      SUPPORTED_METHODS_WITHOUT_OPTIONS = Grape::Util::LazyObject.new { [GET, POST, PUT, PATCH, DELETE, HEAD].freeze }
 
       HTTP_ACCEPT_VERSION    = 'HTTP_ACCEPT_VERSION'
       X_CASCADE              = 'X-Cascade'

lib/grape/util/base_inheritable.rb

@@ -5,8 +5,7 @@ module Util
     # Base for classes which need to operate with own values kept
     # in the hash and inherited values kept in a Hash-like object.
     class BaseInheritable
-      attr_accessor :inherited_values
-      attr_accessor :new_values
+      attr_accessor :inherited_values, :new_values
 
       # @param inherited_values [Object] An object implementing an interface
       #   of the Hash class.
@@ -26,10 +25,14 @@ def initialize_copy(other)
       end
 
       def keys
-        combined = inherited_values.keys
-        combined.concat(new_values.keys)
-        combined.uniq!
-        combined
+        if new_values.any?
+          combined = inherited_values.keys
+          combined.concat(new_values.keys)
+          combined.uniq!
+          combined
+        else
+          inherited_values.keys
+        end
       end
 
       def key?(name)