source: Dev/trunk/src/client/dijit/_TemplatedMixin.js

define([
        "dojo/cache",   // dojo.cache
        "dojo/_base/declare", // declare
        "dojo/dom-construct", // domConstruct.destroy, domConstruct.toDom
        "dojo/_base/lang", // lang.getObject
        "dojo/on",
        "dojo/sniff", // has("ie")
        "dojo/string", // string.substitute string.trim
        "./_AttachMixin"
], function(cache, declare, domConstruct, lang, on, has, string, _AttachMixin){

        // module:
        //              dijit/_TemplatedMixin

        var _TemplatedMixin = declare("dijit._TemplatedMixin", _AttachMixin, {
                // summary:
                //              Mixin for widgets that are instantiated from a template

                // templateString: [protected] String
                //              A string that represents the widget template.
                //              Use in conjunction with dojo.cache() to load from a file.
                templateString: null,

                // templatePath: [protected deprecated] String
                //              Path to template (HTML file) for this widget relative to dojo.baseUrl.
                //              Deprecated: use templateString with require([... "dojo/text!..."], ...) instead
                templatePath: null,

                // skipNodeCache: [protected] Boolean
                //              If using a cached widget template nodes poses issues for a
                //              particular widget class, it can set this property to ensure
                //              that its template is always re-built from a string
                _skipNodeCache: false,

/*=====
                // _rendered: Boolean
                //              Not normally use, but this flag can be set by the app if the server has already rendered the template,
                //              i.e. already inlining the template for the widget into the main page.   Reduces _TemplatedMixin to
                //              just function like _AttachMixin.
                _rendered: false,
=====*/

                // Set _AttachMixin.searchContainerNode to true for back-compat for widgets that have data-dojo-attach-point's
                // and events inside this.containerNode.   Remove for 2.0.
                searchContainerNode: true,

                _stringRepl: function(tmpl){
                        // summary:
                        //              Does substitution of ${foo} type properties in template string
                        // tags:
                        //              private
                        var className = this.declaredClass, _this = this;
                        // Cache contains a string because we need to do property replacement
                        // do the property replacement
                        return string.substitute(tmpl, this, function(value, key){
                                if(key.charAt(0) == '!'){ value = lang.getObject(key.substr(1), false, _this); }
                                if(typeof value == "undefined"){ throw new Error(className+" template:"+key); } // a debugging aide
                                if(value == null){ return ""; }

                                // Substitution keys beginning with ! will skip the transform step,
                                // in case a user wishes to insert unescaped markup, e.g. ${!foo}
                                return key.charAt(0) == "!" ? value :
                                        // Safer substitution, see heading "Attribute values" in
                                        // http://www.w3.org/TR/REC-html40/appendix/notes.html#h-B.3.2
                                        value.toString().replace(/"/g,"""); //TODO: add &amp? use encodeXML method?
                        }, this);
                },

                buildRendering: function(){
                        // summary:
                        //              Construct the UI for this widget from a template, setting this.domNode.
                        // tags:
                        //              protected

                        if(!this._rendered){
                                if(!this.templateString){
                                        this.templateString = cache(this.templatePath, {sanitize: true});
                                }

                                // Lookup cached version of template, and download to cache if it
                                // isn't there already.  Returns either a DomNode or a string, depending on
                                // whether or not the template contains ${foo} replacement parameters.
                                var cached = _TemplatedMixin.getCachedTemplate(this.templateString, this._skipNodeCache, this.ownerDocument);

                                var node;
                                if(lang.isString(cached)){
                                        node = domConstruct.toDom(this._stringRepl(cached), this.ownerDocument);
                                        if(node.nodeType != 1){
                                                // Flag common problems such as templates with multiple top level nodes (nodeType == 11)
                                                throw new Error("Invalid template: " + cached);
                                        }
                                }else{
                                        // if it's a node, all we have to do is clone it
                                        node = cached.cloneNode(true);
                                }

                                this.domNode = node;
                        }

                        // Call down to _WidgetBase.buildRendering() to get base classes assigned
                        // TODO: change the baseClass assignment to _setBaseClassAttr
                        this.inherited(arguments);

                        if(!this._rendered){
                                this._fillContent(this.srcNodeRef);
                        }

                        this._rendered = true;
                },

                _fillContent: function(/*DomNode*/ source){
                        // summary:
                        //              Relocate source contents to templated container node.
                        //              this.containerNode must be able to receive children, or exceptions will be thrown.
                        // tags:
                        //              protected
                        var dest = this.containerNode;
                        if(source && dest){
                                while(source.hasChildNodes()){
                                        dest.appendChild(source.firstChild);
                                }
                        }
                }

        });

        // key is templateString; object is either string or DOM tree
        _TemplatedMixin._templateCache = {};

        _TemplatedMixin.getCachedTemplate = function(templateString, alwaysUseString, doc){
                // summary:
                //              Static method to get a template based on the templatePath or
                //              templateString key
                // templateString: String
                //              The template
                // alwaysUseString: Boolean
                //              Don't cache the DOM tree for this template, even if it doesn't have any variables
                // doc: Document?
                //              The target document.   Defaults to document global if unspecified.
                // returns: Mixed
                //              Either string (if there are ${} variables that need to be replaced) or just
                //              a DOM tree (if the node can be cloned directly)

                // is it already cached?
                var tmplts = _TemplatedMixin._templateCache;
                var key = templateString;
                var cached = tmplts[key];
                if(cached){
                        try{
                                // if the cached value is an innerHTML string (no ownerDocument) or a DOM tree created within the
                                // current document, then use the current cached value
                                if(!cached.ownerDocument || cached.ownerDocument == (doc || document)){
                                        // string or node of the same document
                                        return cached;
                                }
                        }catch(e){ /* squelch */ } // IE can throw an exception if cached.ownerDocument was reloaded
                        domConstruct.destroy(cached);
                }

                templateString = string.trim(templateString);

                if(alwaysUseString || templateString.match(/\$\{([^\}]+)\}/g)){
                        // there are variables in the template so all we can do is cache the string
                        return (tmplts[key] = templateString); //String
                }else{
                        // there are no variables in the template so we can cache the DOM tree
                        var node = domConstruct.toDom(templateString, doc);
                        if(node.nodeType != 1){
                                throw new Error("Invalid template: " + templateString);
                        }
                        return (tmplts[key] = node); //Node
                }
        };

        if(has("ie")){
                on(window, "unload", function(){
                        var cache = _TemplatedMixin._templateCache;
                        for(var key in cache){
                                var value = cache[key];
                                if(typeof value == "object"){ // value is either a string or a DOM node template
                                        domConstruct.destroy(value);
                                }
                                delete cache[key];
                        }
                });
        }

        return _TemplatedMixin;
});