Version 1.5.0-dev.4.14

dart/pkg/web_components/lib/dart_support.js

Index: dart/pkg/web_components/lib/dart_support.js
===================================================================
--- dart/pkg/web_components/lib/dart_support.js	(revision 37358)
+++ dart/pkg/web_components/lib/dart_support.js	(working copy)
@@ -2,6 +2,7 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+// Teaches dart2js about the wrapping that is done by the Shadow DOM polyfill.
 (function() {
   var ShadowDOMPolyfill = window.ShadowDOMPolyfill;
   if (!ShadowDOMPolyfill) return;
@@ -63,3 +64,123 @@
     }
   });
 })();
+
+// Updates document.registerElement so Dart can see when Javascript custom
+// elements are created, and wrap them to provide a Dart friendly API.
+(function (doc) {
+  var upgraders = {};       // upgrader associated with a custom-tag.
+  var unpatchableTags = {}; // set of custom-tags that can't be patched.
+  var pendingElements = {}; // will upgrade when/if an upgrader is installed.
+  var upgradeOldElements = true;
+
+  var originalRegisterElement = doc.registerElement;
+  if (!originalRegisterElement) {
+    throw new Error('document.registerElement is not present.');
+  }
+
+  function reportError(name) {
+    console.error("Couldn't patch prototype to notify Dart when " + name +
+        " elements are created. This can be fixed by making the " +
+        "createdCallback in " + name + " a configurable property.");
+  }
+
+  function registerElement(name, options) {
+    var proto, extendsOption;
+    if (options !== undefined) {
+      proto = options.prototype;
+    } else {
+      proto = Object.create(HTMLElement.prototype);
+      options = {protoptype: proto};
+    }
+
+    var original = proto.createdCallback;
+    var newCallback = function() {
+      original.call(this);
+      var name = (this.getAttribute('is') || this.localName).toLowerCase();
+      var upgrader = upgraders[name];
+      if (upgrader) {
+        upgrader(this);
+      } else if (upgradeOldElements) {
+        // Save this element in case we can upgrade it later when an upgrader is
+        // registered.
+        var list = pendingElements[name];
+        if (!list) {
+          list = pendingElements[name] = [];
+        }
+        list.push(this);
+      }
+    };
+
+    var descriptor = Object.getOwnPropertyDescriptor(proto, 'createdCallback');
+    if (!descriptor || descriptor.writable) {
+      proto.createdCallback = newCallback;
+    } else if (descriptor.configurable) {
+      descriptor['value'] = newCallback;
+      Object.defineProperty(proto, 'createdCallback', descriptor);
+    } else {
+      unpatchableTags[name] = true;
+      if (upgraders[name]) reportError(name);
+    }
+    return originalRegisterElement.call(this, name, options);
+  }
+
+  function registerDartTypeUpgrader(name, upgrader) {
+    if (!upgrader) return;
+    name = name.toLowerCase();
+    var existing = upgraders[name];
+    if (existing) {
+      console.error('Already have a Dart type associated with ' + name);
+      return;
+    }
+    upgraders[name] = upgrader;
+    if (unpatchableTags[name]) reportError(name);
+    if (upgradeOldElements) {
+      // Upgrade elements that were created before the upgrader was registered.
+      var list = pendingElements[name];
+      if (list) {
+        for (var i = 0; i < list.length; i++) {
+          upgrader(list[i]);
+        }
+      }
+      delete pendingElements[name];
+    } else {
+      console.warn("Didn't expect more Dart types to be registered. '" + name
+          + "' elements that already exist in the page might not be wrapped.");
+    }
+  }
+
+  function onlyUpgradeNewElements() {
+    upgradeOldElements = false;
+    pendingElements = null;
+  }
+
+  // Native custom elements outside the app in Chrome have constructor
+  // names like "x-tag", which need to be translated to the DOM
+  // element they extend.  When using the shadow dom polyfill this is
+  // take care of above.
+  var ShadowDOMPolyfill = window.ShadowDOMPolyfill;
+  if (!ShadowDOMPolyfill) {
+    // dartNativeDispatchHooksTransformer is described on initHooks() in
+    // sdk/lib/_internal/lib/native_helper.dart.
+    if (typeof window.dartNativeDispatchHooksTransformer == 'undefined')
+    window.dartNativeDispatchHooksTransformer = [];
+
+    window.dartNativeDispatchHooksTransformer.push(function(hooks) {
+      var originalGetUnknownTag = hooks.getUnknownTag;
+      hooks.getUnknownTag = function(o, tag) {
+        if (/-/.test(tag)) {  // "x-tag"
+          var s = Object.prototype.toString.call(o);
+          var match = s.match(/^\[object ([A-Za-z]*Element)\]$/);
+          if (match) {
+            return match[1];
+	  }
+          return originalGetUnknownTag(o, tag);
+        }
+      };
+    });
+  }
+
+  doc._registerDartTypeUpgrader = registerDartTypeUpgrader;
+  doc._onlyUpgradeNewElements = onlyUpgradeNewElements;
+  doc.registerElement = registerElement;
+})(document);