1 files changed, 105 insertions, 0 deletions
diff --git a/actionview/lib/action_view/view_paths.rb b/actionview/lib/action_view/view_paths.rb
new file mode 100644
index 0000000000..d5694d77f4
--- /dev/null
+++ b/actionview/lib/action_view/view_paths.rb
@@ -0,0 +1,105 @@
+# frozen_string_literal: true
+
+module ActionView
+  module ViewPaths
+    extend ActiveSupport::Concern
+
+    included do
+      class_attribute :_view_paths, default: ActionView::PathSet.new.freeze
+    end
+
+    delegate :template_exists?, :any_templates?, :view_paths, :formats, :formats=,
+             :locale, :locale=, to: :lookup_context
+
+    module ClassMethods
+      def _prefixes # :nodoc:
+        @_prefixes ||= begin
+          return local_prefixes if superclass.abstract?
+
+          local_prefixes + superclass._prefixes
+        end
+      end
+
+      private
+
+        # Override this method in your controller if you want to change paths prefixes for finding views.
+        # Prefixes defined here will still be added to parents' <tt>._prefixes</tt>.
+        def local_prefixes
+          [controller_path]
+        end
+    end
+
+    # The prefixes used in render "foo" shortcuts.
+    def _prefixes # :nodoc:
+      self.class._prefixes
+    end
+
+    # <tt>LookupContext</tt> is the object responsible for holding all
+    # information required for looking up templates, i.e. view paths and
+    # details. Check <tt>ActionView::LookupContext</tt> for more information.
+    def lookup_context
+      @_lookup_context ||=
+        ActionView::LookupContext.new(self.class._view_paths, details_for_lookup, _prefixes)
+    end
+
+    def details_for_lookup
+      {}
+    end
+
+    # Append a path to the list of view paths for the current <tt>LookupContext</tt>.
+    #
+    # ==== Parameters
+    # * <tt>path</tt> - If a String is provided, it gets converted into
+    #   the default view path. You may also provide a custom view path
+    #   (see ActionView::PathSet for more information)
+    def append_view_path(path)
+      lookup_context.view_paths.push(*path)
+    end
+
+    # Prepend a path to the list of view paths for the current <tt>LookupContext</tt>.
+    #
+    # ==== Parameters
+    # * <tt>path</tt> - If a String is provided, it gets converted into
+    #   the default view path. You may also provide a custom view path
+    #   (see ActionView::PathSet for more information)
+    def prepend_view_path(path)
+      lookup_context.view_paths.unshift(*path)
+    end
+
+    module ClassMethods
+      # Append a path to the list of view paths for this controller.
+      #
+      # ==== Parameters
+      # * <tt>path</tt> - If a String is provided, it gets converted into
+      #   the default view path. You may also provide a custom view path
+      #   (see ActionView::PathSet for more information)
+      def append_view_path(path)
+        self._view_paths = view_paths + Array(path)
+      end
+
+      # Prepend a path to the list of view paths for this controller.
+      #
+      # ==== Parameters
+      # * <tt>path</tt> - If a String is provided, it gets converted into
+      #   the default view path. You may also provide a custom view path
+      #   (see ActionView::PathSet for more information)
+      def prepend_view_path(path)
+        self._view_paths = ActionView::PathSet.new(Array(path) + view_paths)
+      end
+
+      # A list of all of the default view paths for this controller.
+      def view_paths
+        _view_paths
+      end
+
+      # Set the view paths.
+      #
+      # ==== Parameters
+      # * <tt>paths</tt> - If a PathSet is provided, use that;
+      #   otherwise, process the parameter into a PathSet.
+      def view_paths=(paths)
+        self._view_paths = ActionView::PathSet.new(Array(paths))
+      end
+    end
+  end
+end