Add ActiveSupport::ArrayInquirer and Array#inquiry

Wrapping an array in an `ArrayInquirer` gives a friendlier way to check its
string-like contents. For example, `request.variant` returns an `ArrayInquirer`
object. To check a request's variants, you can call:

    request.variant.phone?
    request.variant.any?(:phone, :tablet)

...instead of:

    request.variant.include?(:phone)
    request.variant.any? { |v| v.in?([:phone, :tablet]) }

`Array#inquiry` is a shortcut for wrapping the receiving array in an
`ArrayInquirer`:

    pets = [:cat, :dog]
    pets.cat?    # => true
    pets.ferret? # => false
    pets.any?(:cat, :ferret} # => true

1 files changed, 2 insertions, 27 deletions

diff --git a/actionpack/lib/action_dispatch/http/mime_negotiation.rb b/actionpack/lib/action_dispatch/http/mime_negotiation.rb
index 6544aff7d2..ff336b7354 100644
--- a/actionpack/lib/action_dispatch/http/mime_negotiation.rb
+++ b/actionpack/lib/action_dispatch/http/mime_negotiation.rb
@@ -76,7 +76,7 @@ module ActionDispatch
         variant = Array(variant)
 
         if variant.all? { |v| v.is_a?(Symbol) }
-          @variant = VariantInquirer.new(variant)
+          @variant = ActiveSupport::ArrayInquirer.new(variant)
         else
           raise ArgumentError, "request.variant must be set to a Symbol or an Array of Symbols. " \
             "For security reasons, never directly set the variant to a user-provided value, " \
@@ -86,7 +86,7 @@ module ActionDispatch
       end
 
       def variant
-        @variant ||= VariantInquirer.new
+        @variant ||= ActiveSupport::ArrayInquirer.new
       end
 
       # Sets the \format by string extension, which can be used to force custom formats
@@ -141,31 +141,6 @@ module ActionDispatch
         order.include?(Mime::ALL) ? format : nil
       end
 
-      class VariantInquirer # :nodoc:
-        delegate :each, :empty?, to: :@variants
-
-        def initialize(variants = [])
-          @variants = variants
-        end
-
-        def any?(*candidates)
-          (@variants & candidates).any?
-        end
-
-        def to_ary
-          @variants
-        end
-
-        private
-          def method_missing(name, *args)
-            if name[-1] == '?'
-              any? name[0..-2].to_sym
-            else
-              super
-            end
-          end
-      end
-
       protected
 
       BROWSER_LIKE_ACCEPTS = /,\s*\*\/\*|\*\/\*\s*,/