1 files changed, 152 insertions, 0 deletions
diff --git a/actionview/lib/action_view/rendering.rb b/actionview/lib/action_view/rendering.rb
new file mode 100644
index 0000000000..cb4327cf16
--- /dev/null
+++ b/actionview/lib/action_view/rendering.rb
@@ -0,0 +1,152 @@
+# frozen_string_literal: true
+
+require "action_view/view_paths"
+
+module ActionView
+  # This is a class to fix I18n global state. Whenever you provide I18n.locale during a request,
+  # it will trigger the lookup_context and consequently expire the cache.
+  class I18nProxy < ::I18n::Config #:nodoc:
+    attr_reader :original_config, :lookup_context
+
+    def initialize(original_config, lookup_context)
+      original_config = original_config.original_config if original_config.respond_to?(:original_config)
+      @original_config, @lookup_context = original_config, lookup_context
+    end
+
+    def locale
+      @original_config.locale
+    end
+
+    def locale=(value)
+      @lookup_context.locale = value
+    end
+  end
+
+  module Rendering
+    extend ActiveSupport::Concern
+    include ActionView::ViewPaths
+
+    # Overwrite process to setup I18n proxy.
+    def process(*) #:nodoc:
+      old_config, I18n.config = I18n.config, I18nProxy.new(I18n.config, lookup_context)
+      super
+    ensure
+      I18n.config = old_config
+    end
+
+    module ClassMethods
+      def view_context_class
+        @view_context_class ||= begin
+          supports_path = supports_path?
+          routes  = respond_to?(:_routes)  && _routes
+          helpers = respond_to?(:_helpers) && _helpers
+
+          Class.new(ActionView::Base) do
+            if routes
+              include routes.url_helpers(supports_path)
+              include routes.mounted_helpers
+            end
+
+            if helpers
+              include helpers
+            end
+          end
+        end
+      end
+    end
+
+    attr_internal_writer :view_context_class
+
+    def view_context_class
+      @_view_context_class ||= self.class.view_context_class
+    end
+
+    # An instance of a view class. The default view class is ActionView::Base.
+    #
+    # The view class must have the following methods:
+    #
+    # * <tt>View.new(lookup_context, assigns, controller)</tt> — Create a new
+    #   ActionView instance for a controller and we can also pass the arguments.
+    #
+    # * <tt>View#render(option)</tt> — Returns String with the rendered template.
+    #
+    # Override this method in a module to change the default behavior.
+    def view_context
+      view_context_class.new(view_renderer, view_assigns, self)
+    end
+
+    # Returns an object that is able to render templates.
+    def view_renderer # :nodoc:
+      @_view_renderer ||= ActionView::Renderer.new(lookup_context)
+    end
+
+    def render_to_body(options = {})
+      _process_options(options)
+      _render_template(options)
+    end
+
+    def rendered_format
+      Template::Types[lookup_context.rendered_format]
+    end
+
+    private
+
+      # Find and render a template based on the options given.
+      def _render_template(options)
+        variant = options.delete(:variant)
+        assigns = options.delete(:assigns)
+        context = view_context
+
+        context.assign assigns if assigns
+        lookup_context.rendered_format = nil if options[:formats]
+        lookup_context.variants = variant if variant
+
+        view_renderer.render(context, options)
+      end
+
+      # Assign the rendered format to look up context.
+      def _process_format(format)
+        super
+        lookup_context.formats = [format.to_sym]
+        lookup_context.rendered_format = lookup_context.formats.first
+      end
+
+      # Normalize args by converting render "foo" to render :action => "foo" and
+      # render "foo/bar" to render :template => "foo/bar".
+      def _normalize_args(action = nil, options = {})
+        options = super(action, options)
+        case action
+        when NilClass
+        when Hash
+          options = action
+        when String, Symbol
+          action = action.to_s
+          key = action.include?(?/) ? :template : :action
+          options[key] = action
+        else
+          if action.respond_to?(:permitted?) && action.permitted?
+            options = action
+          else
+            options[:partial] = action
+          end
+        end
+
+        options
+      end
+
+      # Normalize options.
+      def _normalize_options(options)
+        options = super(options)
+        if options[:partial] == true
+          options[:partial] = action_name
+        end
+
+        if (options.keys & [:partial, :file, :template]).empty?
+          options[:prefixes] ||= _prefixes
+        end
+
+        options[:template] ||= (options[:action] || action_name).to_s
+        options
+      end
+  end
+end