1 files changed, 87 insertions, 0 deletions
diff --git a/actionpack/lib/action_view/renderable.rb b/actionpack/lib/action_view/renderable.rb
new file mode 100644
index 0000000000..46193670f3
--- /dev/null
+++ b/actionpack/lib/action_view/renderable.rb
@@ -0,0 +1,87 @@
+module ActionView
+  module Renderable
+    # NOTE: The template that this mixin is beening include into is frozen
+    # So you can not set or modify any instance variables
+
+    def self.included(base)
+      @@mutex = Mutex.new
+    end
+
+    include ActiveSupport::Memoizable
+
+    def filename
+      'compiled-template'
+    end
+
+    def handler
+      Template.handler_class_for_extension(extension)
+    end
+    memoize :handler
+
+    def compiled_source
+      handler.new(nil).compile(self) if handler.compilable?
+    end
+    memoize :compiled_source
+
+    def render(view, local_assigns = {})
+      view._first_render ||= self
+      view._last_render = self
+      view.send(:evaluate_assigns)
+      compile(local_assigns) if handler.compilable?
+      handler.new(view).render(self, local_assigns)
+    end
+
+    def method(local_assigns)
+      if local_assigns && local_assigns.any?
+        local_assigns_keys = "locals_#{local_assigns.keys.map { |k| k.to_s }.sort.join('_')}"
+      end
+      ['_run', extension, method_segment, local_assigns_keys].compact.join('_').to_sym
+    end
+
+    private
+      # Compile and evaluate the template's code (if necessary)
+      def compile(local_assigns)
+        render_symbol = method(local_assigns)
+
+        @@mutex.synchronize do
+          if recompile?(render_symbol)
+            compile!(render_symbol, local_assigns)
+          end
+        end
+      end
+
+      def compile!(render_symbol, local_assigns)
+        locals_code = local_assigns.keys.map { |key| "#{key} = local_assigns[:#{key}];" }.join
+
+        source = <<-end_src
+          def #{render_symbol}(local_assigns)
+            old_output_buffer = output_buffer;#{locals_code};#{compiled_source}
+          ensure
+            self.output_buffer = old_output_buffer
+          end
+        end_src
+
+        begin
+          logger = ActionController::Base.logger
+          logger.debug "Compiling template #{render_symbol}" if logger
+
+          ActionView::Base::CompiledTemplates.module_eval(source, filename, 0)
+        rescue Exception => e # errors from template code
+          if logger
+            logger.debug "ERROR: compiling #{render_symbol} RAISED #{e}"
+            logger.debug "Function body: #{source}"
+            logger.debug "Backtrace: #{e.backtrace.join("\n")}"
+          end
+
+          raise ActionView::TemplateError.new(self, {}, e)
+        end
+      end
+
+      # Method to check whether template compilation is necessary.
+      # The template will be compiled if the file has not been compiled yet, or
+      # if local_assigns has a new key, which isn't supported by the compiled code yet.
+      def recompile?(symbol)
+        !(frozen? && Base::CompiledTemplates.method_defined?(symbol))
+      end
+  end
+end