1 files changed, 127 insertions, 0 deletions
diff --git a/actionpack/lib/abstract_controller/rendering.rb b/actionpack/lib/abstract_controller/rendering.rb
new file mode 100644
index 0000000000..8ba2b25552
--- /dev/null
+++ b/actionpack/lib/abstract_controller/rendering.rb
@@ -0,0 +1,127 @@
+# frozen_string_literal: true
+
+require "abstract_controller/error"
+require "action_view"
+require "action_view/view_paths"
+require "set"
+
+module AbstractController
+  class DoubleRenderError < Error
+    DEFAULT_MESSAGE = "Render and/or redirect were called multiple times in this action. Please note that you may only call render OR redirect, and at most once per action. Also note that neither redirect nor render terminate execution of the action, so if you want to exit an action after redirecting, you need to do something like \"redirect_to(...) and return\"."
+
+    def initialize(message = nil)
+      super(message || DEFAULT_MESSAGE)
+    end
+  end
+
+  module Rendering
+    extend ActiveSupport::Concern
+    include ActionView::ViewPaths
+
+    # Normalizes arguments, options and then delegates render_to_body and
+    # sticks the result in <tt>self.response_body</tt>.
+    def render(*args, &block)
+      options = _normalize_render(*args, &block)
+      rendered_body = render_to_body(options)
+      if options[:html]
+        _set_html_content_type
+      else
+        _set_rendered_content_type rendered_format
+      end
+      self.response_body = rendered_body
+    end
+
+    # Raw rendering of a template to a string.
+    #
+    # It is similar to render, except that it does not
+    # set the +response_body+ and it should be guaranteed
+    # to always return a string.
+    #
+    # If a component extends the semantics of +response_body+
+    # (as ActionController extends it to be anything that
+    # responds to the method each), this method needs to be
+    # overridden in order to still return a string.
+    def render_to_string(*args, &block)
+      options = _normalize_render(*args, &block)
+      render_to_body(options)
+    end
+
+    # Performs the actual template rendering.
+    def render_to_body(options = {})
+    end
+
+    # Returns Content-Type of rendered content.
+    def rendered_format
+      Mime[:text]
+    end
+
+    DEFAULT_PROTECTED_INSTANCE_VARIABLES = Set.new %i(
+      @_action_name @_response_body @_formats @_prefixes
+    )
+
+    # This method should return a hash with assigns.
+    # You can overwrite this configuration per controller.
+    def view_assigns
+      protected_vars = _protected_ivars
+      variables      = instance_variables
+
+      variables.reject! { |s| protected_vars.include? s }
+      variables.each_with_object({}) { |name, hash|
+        hash[name.slice(1, name.length)] = instance_variable_get(name)
+      }
+    end
+
+  private
+    # Normalize args by converting <tt>render "foo"</tt> to
+    # <tt>render :action => "foo"</tt> and <tt>render "foo/bar"</tt> to
+    # <tt>render :file => "foo/bar"</tt>.
+    def _normalize_args(action = nil, options = {}) # :doc:
+      if action.respond_to?(:permitted?)
+        if action.permitted?
+          action
+        else
+          raise ArgumentError, "render parameters are not permitted"
+        end
+      elsif action.is_a?(Hash)
+        action
+      else
+        options
+      end
+    end
+
+    # Normalize options.
+    def _normalize_options(options) # :doc:
+      options
+    end
+
+    # Process extra options.
+    def _process_options(options) # :doc:
+      options
+    end
+
+    # Process the rendered format.
+    def _process_format(format) # :nodoc:
+    end
+
+    def _process_variant(options)
+    end
+
+    def _set_html_content_type # :nodoc:
+    end
+
+    def _set_rendered_content_type(format) # :nodoc:
+    end
+
+    # Normalize args and options.
+    def _normalize_render(*args, &block) # :nodoc:
+      options = _normalize_args(*args, &block)
+      _process_variant(options)
+      _normalize_options(options)
+      options
+    end
+
+    def _protected_ivars # :nodoc:
+      DEFAULT_PROTECTED_INSTANCE_VARIABLES
+    end
+  end
+end