1 files changed, 120 insertions, 0 deletions
diff --git a/actionpack/lib/action_view/reloadable_template.rb b/actionpack/lib/action_view/reloadable_template.rb
new file mode 100644
index 0000000000..3081be60fd
--- /dev/null
+++ b/actionpack/lib/action_view/reloadable_template.rb
@@ -0,0 +1,120 @@
+module ActionView #:nodoc:
+  class ReloadableTemplate < Template
+
+    class TemplateDeleted < ActionView::ActionViewError
+    end
+
+    class ReloadablePath < Template::Path
+
+      def initialize(path)
+        super
+        @paths = {}
+        new_request!
+      end
+
+      def new_request!
+        @disk_cache = {}
+      end
+      alias_method :load!, :new_request!
+
+      def [](path)
+        if found_template = @paths[path]
+          begin
+            found_template.reset_cache_if_stale!
+          rescue TemplateDeleted
+            unregister_template(found_template)
+            self[path]
+          end
+        else
+          load_all_templates_from_dir(templates_dir_from_path(path))
+          @paths[path]
+        end
+      end
+
+      def register_template_from_file(template_file_path)
+        if !@paths[template_relative_path = template_file_path.split("#{@path}/").last] && File.file?(template_file_path)
+          register_template(ReloadableTemplate.new(template_relative_path, self))
+        end
+      end
+
+      def register_template(template)
+        template.accessible_paths.each do |path|
+          @paths[path] = template
+        end
+      end
+
+      # remove (probably deleted) template from cache
+      def unregister_template(template)
+        template.accessible_paths.each do |template_path|
+          @paths.delete(template_path) if @paths[template_path] == template
+        end
+        # fill in any newly created gaps
+        @paths.values.uniq.each do |template|
+          template.accessible_paths.each {|path| @paths[path] ||= template}
+        end
+      end
+
+      # load all templates from the directory of the requested template
+      def load_all_templates_from_dir(dir)
+        # hit disk only once per template-dir/request
+        @disk_cache[dir] ||= template_files_from_dir(dir).each {|template_file| register_template_from_file(template_file)}
+      end
+
+      def templates_dir_from_path(path)
+        dirname = File.dirname(path)
+        File.join(@path, dirname == '.' ? '' : dirname)
+      end
+
+      # get all the template filenames from the dir
+      def template_files_from_dir(dir)
+        Dir.glob(File.join(dir, '*'))
+      end
+
+    end
+
+    module Unfreezable
+      def freeze; self; end
+    end
+
+    def initialize(*args)
+      super
+      @compiled_methods = []
+      
+      # we don't ever want to get frozen
+      extend Unfreezable
+    end
+
+    def mtime
+      File.mtime(filename)
+    end
+
+    attr_accessor :previously_last_modified
+
+    def stale?
+      previously_last_modified.nil? || previously_last_modified < mtime
+    rescue Errno::ENOENT => e
+      undef_my_compiled_methods!
+      raise TemplateDeleted
+    end
+
+    def reset_cache_if_stale!
+      if stale?
+        flush_cache 'source', 'compiled_source'
+        undef_my_compiled_methods!
+        @previously_last_modified = mtime
+      end
+      self
+    end
+
+    def undef_my_compiled_methods!
+      @compiled_methods.each {|comp_method| ActionView::Base::CompiledTemplates.send(:remove_method, comp_method)}
+      @compiled_methods.clear
+    end
+
+    def compile!(render_symbol, local_assigns)
+      super
+      @compiled_methods << render_symbol
+    end
+
+  end
+end