jakemac@google.com
aedbb32333
Revert "Revert "update platform.js to get memory leak fixes"" R=jmesserly@google.com Review URL: https://codereview.chromium.org//617413002 git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@40854 260f80e4-7a28-3924-810f-c04153c831b5
62 lines
2.4 KiB
Dart
62 lines
2.4 KiB
Dart
// Copyright (c) 2013, the Dart project authors. Please see the AUTHORS file
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// for details. All rights reserved. Use of this source code is governed by a
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// BSD-style license that can be found in the LICENSE file.
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/** Dart APIs for interacting with the JavaScript Custom Elements polyfill. */
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library web_components.polyfill;
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import 'dart:async';
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import 'dart:html';
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import 'dart:js' as js;
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/**
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* A future that completes once all custom elements in the initial HTML page
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* have been upgraded.
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*
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* This is needed because the native implementation can update the elements
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* while parsing the HTML document, but the custom element polyfill cannot,
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* so it completes this future once all elements are upgraded.
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*/
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// TODO(jmesserly): rename to webComponentsReady to match the event?
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Future customElementsReady = () {
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if (_isReady) return new Future.value();
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// Not upgraded. Wait for the polyfill to fire the WebComponentsReady event.
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// Note: we listen on document (not on document.body) to allow this polyfill
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// to be loaded in the HEAD element.
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return document.on['WebComponentsReady'].first;
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}();
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// Return true if we are using the polyfill and upgrade is complete, or if we
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// have native document.register and therefore the browser took care of it.
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// Otherwise return false, including the case where we can't find the polyfill.
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bool get _isReady {
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// If we don't have dart:js, assume things are ready
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if (js.context == null) return true;
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var customElements = js.context['CustomElements'];
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if (customElements == null) {
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// Return true if native document.register, otherwise false.
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// (Maybe the polyfill isn't loaded yet. Wait for it.)
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return document.supportsRegister;
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}
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return customElements['ready'] == true;
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}
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/**
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* *Note* this API is primarily intended for tests. In other code it is better
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* to write it in a style that works with or without the polyfill, rather than
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* using this method.
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*
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* Synchronously trigger evaluation of pending lifecycle events, which otherwise
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* need to wait for a [MutationObserver] to signal the changes in the polyfill.
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* This method can be used to resolve differences in timing between native and
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* polyfilled custom elements.
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*/
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void customElementsTakeRecords([Node node]) {
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var customElements = js.context['CustomElements'];
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if (customElements == null) return;
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customElements.callMethod('takeRecords', [node]);
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}
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