Move client/{base, observable, layout, touch, util, view} to samples/ui_lib .

client/observable/ChangeEvent.dart

-// Copyright (c) 2011, 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.
-
-/** A change to an observable instance. */
-class ChangeEvent {
-  // TODO(sigmund): capture language issues around enums & create a cannonical
-  // Dart enum design.
-  /** Type denoting an in-place update event. */
-  static final UPDATE = 0;
-
-  /** Type denoting an insertion event. */
-  static final INSERT = 1;
-
-  /** Type denoting a single-remove event. */
-  static final REMOVE = 2;
-
-  /**
-   * Type denoting events that affect the entire observable instance. For
-   * example, a list operation like clear or sort.
-   */
-  static final GLOBAL = 3;
-
-  /** The observable instance that changed. */
-  final Observable target;
-
-  /** Whether the change was an [INSERT], [REMOVE], or [UPDATE]. */
-  final int type;
-
-  /** The value after the change (or inserted value in a list). */
-  final newValue = null;
-
-  /** The value before the change (or removed value from a list). */
-  final oldValue = null;
-
-  /** Property that changed (null for list changes). */
-  final String propertyName = null;
-
-  /**
-   * Index of the list operation. Insertions prepend in front of the given
-   * index (insert at 0 means an insertion at the beginning of the list).
-   */
-  final int index = null;
-
-  /** Factory constructor for property change events. */
-  ChangeEvent.property(
-      this.target, this.propertyName, this.newValue, this.oldValue)
-    : type = UPDATE;
-
-  /** Factory constructor for list change events. */
-  ChangeEvent.list(
-      this.target, this.type, this.index, this.newValue, this.oldValue);
-
-  /** Factory constructor for [GLOBAL] change events. */
-  ChangeEvent.global(this.target) : type = GLOBAL;
-}
-
-/** A collection of change events on a single observable instance. */
-class EventSummary {
-  final Observable target;
-
-  // TODO(sigmund): evolve this to track changes per property.
-  List<ChangeEvent> events;
-
-  EventSummary(this.target) : events = new List<ChangeEvent>();
-
-  void addEvent(ChangeEvent e) {
-    events.add(e);
-  }
-
-  /** Notify listeners of [target] and parents of [target] about all changes. */
-  void notify() {
-    if (!events.isEmpty()) {
-      for (Observable obj = target; obj != null; obj = obj.parent) {
-        for (final listener in obj.listeners) {
-          listener(this);
-        }
-      }
-    }
-  }
-}
-
-/** A listener of change events. */
-typedef void ChangeListener(EventSummary events);