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, 38 insertions, 0 deletions

diff --git a/activesupport/lib/active_support/array_inquirer.rb b/activesupport/lib/active_support/array_inquirer.rb
new file mode 100644
index 0000000000..0ae534da00
--- /dev/null
+++ b/activesupport/lib/active_support/array_inquirer.rb
@@ -0,0 +1,38 @@
+module ActiveSupport
+  # Wrapping an array in an +ArrayInquirer+ gives a friendlier way to check
+  # its string-like contents:
+  #
+  #   variants = ActiveSupport::ArrayInquirer.new([:phone, :tablet])
+  #
+  #   variants.phone?    # => true
+  #   variants.tablet?   # => true
+  #   variants.desktop?  # => false
+  #
+  #   variants.any?(:phone, :tablet)   # => true
+  #   variants.any?(:phone, :desktop)  # => true
+  #   variants.any?(:desktop, :watch)  # => false
+  class ArrayInquirer < Array
+    def any?(*candidates, &block)
+      if candidates.none?
+        super
+      else
+        candidates.any? do |candidate|
+          include?(candidate) || include?(candidate.to_sym)
+        end
+      end
+    end
+
+    private
+      def respond_to_missing?(name, include_private = false)
+        name[-1] == '?'
+      end
+
+      def method_missing(name, *args)
+        if name[-1] == '?'
+          any?(name[0..-2])
+        else
+          super
+        end
+      end
+  end
+end