Added express middleware for pre-rendering layouts as well as support…

… for UA based partials

lib/express.js

@@ -4,11 +4,75 @@
 */
 YUI.add('express', function(Y) {
 
+    if (YUI.express) {
+        //Catch double loading of YUI().use('*');
+        return;
+    }
+
     var path = YUI.require('path'),
         fs = YUI.require('fs'),
         sys = YUI.require('sys'),
         DEBUG = false;
+    /**
+    * The default content holder for partials, if one is not given this one is used.
+    * @property defaultContent
+    * @static
+    */
+    YUI.defaultContent = '#content';
 
+    /**
+    * Express middleware to "pre-parse" the layout and add it to a YUI instance
+    * that is then bound to the req as req.Y. Calling res.send() will automatically call
+    * Y.config.doc.outerHTML and echo to the response.
+    * The middleware can be used like this: http://gist.github.com/657453
+    * @static
+    * @method express
+    */
+    YUI.express = function(req, res, next) {
+        var fn = function(req, res, next, yConfig) {
+            if (!req.Y) {
+                var ua = req.headers['user-agent'];
+                YUI({ debug: DEBUG, UA: ua }).use('*', function(Y) {
+                    Y.config.win.location.href = req.originalUrl;
+                    Y.express = yConfig;
+                    req.Y = res.Y = Y;
+                    if (yConfig.render) {
+                        res._ySend = res.send;
+                        res.sub = function(sub) {
+                            var html = this.Y.config.doc.outerHTML;
+                            html = this.Y.substitute(html, sub);
+                            this.Y.config.doc.innerHTML = html;
+                        };
+                        res.send = function(str) {
+                            Y.config.doc.innerHTML = str;
+                            this.send = function() {
+                                this._ySend.call(this, Y.config.doc.outerHTML);
+                                req.Y = res.Y = null;
+                                YUI._express[Y.id] = Y;
+                                YUI.cleanExpress();
+                            };
+                            next();
+                        };
+                        var c = {};
+                        if (yConfig.locals) {
+                            c.locals = yConfig.locals;
+                        }
+                        res.render(yConfig.render, c);
+                    }
+                });
+            } else {
+                next();
+            }
+        };
+        if (req && res && next) {
+            return fn.call(this, req, res, next);
+        } else {
+            return function(req2, res2, next2) {
+                fn.call(this, req2, res2, next2, req);
+            };
+        }
+    };
+
     /**
     * Hash of all YUI instances uses in the course of rendering the pages.
     * So they can be blown away after they are used.
@@ -64,9 +128,11 @@ YUI.add('express', function(Y) {
     * {
     *   name: 'header', //Name of the /views/partial/{name}.html file to load
     *   method: 'append', //append,prepend,appendChild
-    *   node: '#conent', //Any valid selector
+    *   node: '#content', //Any valid selector
     *   enum: 'one', //one,all
-    *   fn: function //The callback function to run after the action.
+    *   fn: function, //The callback function to run after the action.
+    *   ua: 'webkit', //Any truthy value from Y.UA
+    *   test: function(Y, options) //Test function passed Y instance and render options. Return true to include this partial.
     * }
     * @property partials
     * @static
@@ -141,7 +207,10 @@ YUI.add('express', function(Y) {
     YUI.render = function(content, options) {
         var eY, locals = options.locals,
             ua = options.scope.headers['user-agent'];
-
+
+        if (options.scope.res.Y && !options.partial) {
+            locals.instance = options.scope.res.Y;
+        }
         if (locals.instance) {
             eY = locals.instance;
             eY.UA = YUI.Env.parseUA(ua);
@@ -185,16 +254,34 @@ YUI.add('express', function(Y) {
             }
             if (parts && parts.length) {
                 eY.each(parts, function(p) {
-                    var str = locals.partial(p.name);
-                    var enum = p.enum || 'one';
-                    var method = p.method || 'append';
-                    eY[enum](p.node)[method](str);
-                    if (p.fn) {
-                        p.fn(eY, options, p);
+                    var run = true;
+                    if (p.test && eY.Lang.isFunction(p.test)) {
+                        run = false;
+                        if (p.test(eY, options)) {
+                            run = true;
+                        }
+                    }
+                    if (p.ua) {
+                        run = false;
+                        if (eY.UA[p.ua]) {
+                            run = true;
+                        }
+                    }
+                    if (run) {
+                        var str = locals.partial(p.name);
+                        var enum = p.enum || 'one';
+                        var method = p.method || 'append';
+                        eY[enum](p.node)[method](str);
+                        if (p.fn) {
+                            p.fn(eY, options, p);
+                        }
                     }
                 });
             }
             var html = docType + "\n";
+            if (!locals.content) {
+                locals.content = YUI.defaultContent;
+            }
             var content = eY.one(locals.content);
             if (content && locals.body) {
                 content.prepend(locals.body);
@@ -209,7 +296,9 @@ YUI.add('express', function(Y) {
             if (locals.sub) {
               html = eY.substitute(html, locals.sub);
             }
-            YUI._express[eY.id] = eY;
+            if (!options.scope.res.Y) {
+                YUI._express[eY.id] = eY;
+            }
             YUI.cleanExpress();
             return html;
         } else {