PERF: use raw rendering for topic list

rename my handlebars helper to "raw",
create ember compat handlebars to handle rendering
patch ember rails to use the correct precompiler

app/assets/javascripts/discourse/helpers/raw.js.es6

@@ -1,4 +1,4 @@
-Handlebars.registerHelper('handlebars', function(property, options) {
+Handlebars.registerHelper('raw', function(property, options) {
 
   var template = Em.TEMPLATES[property + ".raw"];
   var params = options.hash;
@@ -13,7 +13,3 @@ Handlebars.registerHelper('handlebars', function(property, options) {
 
   return new Handlebars.SafeString(template(params));
 });
-
-Handlebars.registerHelper('get', function(property) {
-  return Em.get(this, property);
-});

app/assets/javascripts/discourse/lib/ember_compat_handlebars.js

@@ -0,0 +1,105 @@
+// keep IIF for simpler testing
+
+// EmberCompatHandlebars is a mechanism for quickly rendering templates which is Ember aware
+// templates are highly compatible with Ember so you don't need to worry about calling "get"
+// and computed properties function, additionally it uses stringParams like Ember does
+
+(function(){
+
+  // compat with ie8 in case this gets picked up elsewhere
+  var objectCreate = Object.create || function(parent) {
+    function F() {}
+    F.prototype = parent;
+    return new F();
+  };
+
+
+  var RawHandlebars = objectCreate(Handlebars);
+
+  RawHandlebars.helper = function() {};
+  RawHandlebars.helpers = objectCreate(Handlebars.helpers);
+
+  RawHandlebars.helpers.get = function(context, options){
+    var firstContext =  options.contexts[0];
+    var val = firstContext[context];
+    val = val === undefined ? Em.get(firstContext, context): val;
+    return val;
+  };
+
+  // adds compatability so this works with stringParams
+  var stringCompatHelper = function(fn){
+
+    var old = RawHandlebars.helpers[fn];
+    RawHandlebars.helpers[fn] = function(context,options){
+      return old.apply(this, [
+          RawHandlebars.helpers.get(context,options),
+          options
+      ]);
+    };
+  };
+
+  stringCompatHelper("each");
+  stringCompatHelper("if");
+  stringCompatHelper("unless");
+  stringCompatHelper("with");
+
+
+  RawHandlebars.Compiler = function() {};
+  RawHandlebars.Compiler.prototype = objectCreate(Handlebars.Compiler.prototype);
+  RawHandlebars.Compiler.prototype.compiler = RawHandlebars.Compiler;
+
+  RawHandlebars.JavaScriptCompiler = function() {};
+
+  RawHandlebars.JavaScriptCompiler.prototype = objectCreate(Handlebars.JavaScriptCompiler.prototype);
+  RawHandlebars.JavaScriptCompiler.prototype.compiler = RawHandlebars.JavaScriptCompiler;
+  RawHandlebars.JavaScriptCompiler.prototype.namespace = "Discourse.EmberCompatHandlebars";
+
+
+  RawHandlebars.Compiler.prototype.mustache = function(mustache) {
+    if ( !(mustache.params.length || mustache.hash)) {
+
+      var id = new Handlebars.AST.IdNode([{ part: 'get' }]);
+
+      if (!mustache.escaped) {
+        mustache.hash = mustache.hash || new Handlebars.AST.HashNode([]);
+        mustache.hash.pairs.push(["unescaped", new Handlebars.AST.StringNode("true")]);
+      }
+      mustache = new Handlebars.AST.MustacheNode([id].concat([mustache.id]), mustache.hash, !mustache.escaped);
+    }
+
+    return Handlebars.Compiler.prototype.mustache.call(this, mustache);
+  };
+
+  RawHandlebars.precompile = function(value, asObject) {
+    var ast = Handlebars.parse(value);
+
+    var options = {
+      knownHelpers: {
+        get: true
+      },
+      data: true,
+      stringParams: true
+    };
+
+    asObject = asObject === undefined ? true : asObject;
+
+    var environment = new RawHandlebars.Compiler().compile(ast, options);
+    return new RawHandlebars.JavaScriptCompiler().compile(environment, options, undefined, asObject);
+  };
+
+
+  RawHandlebars.compile = function(string) {
+    var ast = Handlebars.parse(string);
+    // this forces us to rewrite helpers
+    var options = {  data: true, stringParams: true };
+    var environment = new RawHandlebars.Compiler().compile(ast, options);
+    var templateSpec = new RawHandlebars.JavaScriptCompiler().compile(environment, options, undefined, true);
+
+    var template = RawHandlebars.template(templateSpec);
+
+    return template;
+  };
+
+  Discourse.EmberCompatHandlebars = RawHandlebars;
+
+})();

app/assets/javascripts/discourse/templates/components/basic-topic-list.hbs

@@ -48,7 +48,7 @@
               {{number topic.views numberKey="views_long"}}
             </td>
 
-            {{handlebars "list/activity_column" topic=topic class="num" tagName="td"}}
+            {{raw "list/activity_column" topic=topic class="num" tagName="td"}}
           </tr>
         {{/grouped-each}}
       </tbody>

app/assets/javascripts/discourse/templates/list/activity_column.raw.hbs

@@ -1 +1 @@
-<{{this.tagName}} class="{{cold-age-class "topic.createdAt" startDate="topic.bumpedAt" class=this.class}} activity" title="{{get "topic.bumpedAtTitle"}}"><a href="{{get "topic.lastPostUrl"}}">{{format-date "topic.bumpedAt" format="tiny" noTitle=true}}</a></{{this.tagName}}>
+<{{this.tagName}} class="{{class}} {{cold-age-class topic.createdAt startDate=topic.bumpedAt class=""}} activity" title="{{topic.bumpedAtTitle}}"><a href="{{topic.lastPostUrl}}">{{format-date topic.bumpedAt format="tiny" noTitle=true}}</a></{{this.tagName}}>

app/assets/javascripts/discourse/templates/list/category_column.raw.hbs

@@ -1,3 +1,3 @@
 {{#unless hideCategory}}
-<td class='category'>{{category-link "category" showParent=true}}</td>
+<td class='category'>{{category-link category showParent=true}}</td>
 {{/unless}}

app/assets/javascripts/discourse/templates/list/posters_column.raw.hbs

@@ -1,5 +1,5 @@
 <td class='posters'>
 {{#each posters}}
-<a href="{{get "user.path"}}" data-user-card="{{this.user.username}}" class="{{get "extras"}}">{{avatar this usernamePath="user.username" imageSize="small"}}</a>
+<a href="{{user.path}}" data-user-card="{{user.username}}" class="{{extras}}">{{avatar this usernamePath="user.username" imageSize="small"}}</a>
 {{/each}}
 </td>

app/assets/javascripts/discourse/templates/list/topic_list_item.hbs

@@ -27,10 +27,10 @@
   {{/if}}
 </td>
 
-{{handlebars "list/category_column" hideCategory=hideCategory category=category}}
-{{handlebars "list/posters_column" posters=posters}}
+{{raw "list/category_column" hideCategory=hideCategory category=category}}
+{{raw "list/posters_column" posters=posters}}
 
 {{posts-count-column topic=model class="num" action="showTopicEntrance"}}
 <td class="num views {{unbound viewsHeat}}">{{number views numberKey="views_long"}}</td>
 
-{{handlebars "list/activity_column" topic=model class="num" tagName="td"}}
+{{raw "list/activity_column" topic=model class="num" tagName="td"}}

app/assets/javascripts/discourse/templates/mobile/components/basic-topic-list.hbs

@@ -27,7 +27,7 @@
             <div class="topic-item-stats clearfix">
               <div class="pull-right">
                 {{posts-count-column topic=topic tagName="div" class="num posts" action="clickedPosts"}}
-                {{handlebars "list/activity_column" topic=topic tagName="div" class="num activity last"}}
+                {{raw "list/activity_column" topic=topic tagName="div" class="num activity last"}}
               </div>
               {{#unless controller.hideCategory}}
                 <div class='category'>

app/assets/javascripts/discourse/templates/mobile/list/topic_list_item.hbs

@@ -31,7 +31,7 @@
     {{posts-count-column topic=this tagName="div" class="num posts" action="showTopicEntrance"}}
     <div class='num activity last'>
       <a href="{{lastPostUrl}}" title='{{i18n last_post}}: {{{raw-date bumped_at}}}'>{{last_poster_username}}</a>
-      {{handlebars "list/activity_column" topic=this tagName="span" class="age"}}
+      {{raw "list/activity_column" topic=this tagName="span" class="age"}}
     </div>
   </div>
   <div class="clearfix"></div>

app/assets/javascripts/main_include.js

@@ -8,8 +8,10 @@
 // This is a BUG we should fix
 // it is only required here cause preview is not loading it using LAB
 //= require highlight.pack.js
+//
 
 // Stuff we need to load first
+//= require ./discourse/lib/ember_compat_handlebars
 //= require ./discourse/lib/computed
 //= require ./discourse/mixins/scrolling
 //= require_tree ./discourse/mixins

lib/freedom_patches/ember_compat_handlebars.rb

@@ -0,0 +1,36 @@
+# barber patches to re-route raw compilation via ember compat handlebars
+#
+
+module Barber
+  class EmberCompatPrecompiler < Barber::Precompiler
+
+    def self.call(template)
+      "Handlebars.template(#{compile(template)})"
+    end
+
+    def sources
+      [handlebars, precompiler]
+    end
+
+    def precompiler
+    @precompiler ||= StringIO.new <<END
+      var Discourse = {};
+      #{File.read(Rails.root + "app/assets/javascripts/discourse/lib/ember_compat_handlebars.js")}
+      var Barber = {
+        precompile: function(string) {
+          return Discourse.EmberCompatHandlebars.precompile(string).toString();
+        }
+      };
+END
+    end
+  end
+end
+
+class Ember::Handlebars::Template
+  def precompile_handlebars(string)
+    "Discourse.EmberCompatHandlebars.template(#{Barber::EmberCompatPrecompiler.compile(string)});"
+  end
+  def compile_handlebars(string)
+    "Discourse.EmberCompatHandlebars.compile(#{indent(string).inspect});"
+  end
+end