Implement Model-Driven-Views spec for Dart

tools/dom/src/ModelTreeObserver.dart

-// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
-// 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.
-
-part of html;
-
-class _ModelTreeObserver {
-  static bool _initialized = false;
-
-  /**
-   * Start an observer watching the document for tree changes to automatically
-   * propagate model changes.
-   *
-   * Currently this does not support propagation through Shadow DOMs.
-   */
-  static void initialize() {
-    if (!_initialized) {
-      _initialized = true;
-
-      if (MutationObserver.supported) {
-        var observer = new MutationObserver(_processTreeChange);
-        observer.observe(document, childList: true, subtree: true);
-      } else {
-        document.on['DOMNodeInserted'].listen(_handleNodeInserted);
-        document.on['DOMNodeRemoved'].listen(_handleNodeRemoved);
-      }
-    }
-  }
-
-  static void _processTreeChange(List<MutationRecord> mutations,
-      MutationObserver observer) {
-    for (var record in mutations) {
-      for (var node in record.addedNodes) {
-        // When nodes enter the document we need to make sure that all of the
-        // models are properly propagated through the entire sub-tree.
-        propagateModel(node, _calculatedModel(node), true);
-      }
-      for (var node in record.removedNodes) {
-        propagateModel(node, _calculatedModel(node), false);
-      }
-    }
-  }
-
-  static void _handleNodeInserted(MutationEvent e) {
-    var node = e.target;
-    window.setImmediate(() {
-      propagateModel(node, _calculatedModel(node), true);
-    });
-  }
-
-  static void _handleNodeRemoved(MutationEvent e) {
-    var node = e.target;
-    window.setImmediate(() {
-      propagateModel(node, _calculatedModel(node), false);
-    });
-  }
-
-  /**
-   * Figures out what the model should be for a node, avoiding any cached
-   * model values.
-   */
-  static _calculatedModel(node) {
-    if (node._hasLocalModel == true) {
-      return node._model;
-    } else if (node.parentNode != null) {
-      return node.parentNode._model;
-    }
-    return null;
-  }
-
-  /**
-   * Pushes model changes down through the tree.
-   *
-   * Set fullTree to true if the state of the tree is unknown and model changes
-   * should be propagated through the entire tree.
-   */
-  static void propagateModel(Node node, model, bool fullTree) {
-    // Calling into user code with the != call could generate exceptions.
-    // Catch and report them a global exceptions.
-    try {
-      if (node._hasLocalModel != true && node._model != model &&
-          node._modelChangedStreams != null &&
-          !node._modelChangedStreams.isEmpty) {
-        node._model = model;
-        node._modelChangedStreams.toList()
-          .forEach((controller) => controller.add(node));
-      }
-    } catch (e, s) {
-      new Future.error(e, s);
-    }
-    for (var child = node.$dom_firstChild; child != null;
-        child = child.nextNode) {
-      if (child._hasLocalModel != true) {
-        propagateModel(child, model, fullTree);
-      } else if (fullTree) {
-        propagateModel(child, child._model, true);
-      }
-    }
-  }
-}