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

client/observable/observable.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.
-
-#library('observable');
-
-#import('dart:coreimpl');
-
-#source('ChangeEvent.dart');
-#source('EventBatch.dart');
-
-/**
- * An object whose changes are tracked and who can issue events notifying how it
- * has been changed.
- */
-interface Observable {
-  /** Returns a globally unique identifier for the object. */
-  // TODO(sigmund): remove once dart supports maps with arbitrary keys.
-  final int uid;
-
-  /** Listeners on this model. */
-  final List<ChangeListener> listeners;
-
-  /** The parent observable to notify when this child is changed. */
-  final Observable parent;
-
-  /**
-   * Adds a listener for changes on this observable instance. Returns whether
-   * the listener was added successfully.
-   */
-  bool addChangeListener(ChangeListener listener);
-
-  /**
-   * Removes a listener for changes on this observable instance. Returns whether
-   * the listener was removed successfully.
-   */
-  bool removeChangeListener(ChangeListener listener);
-}
-
-
-/** Common functionality for observable objects. */
-class AbstractObservable implements Observable {
-
-  /** Unique id to identify this model in an event batch. */
-  final int uid;
-
-  /** The parent observable to notify when this child is changed. */
-  final Observable parent;
-
-  /** Listeners on this model. */
-  List<ChangeListener> listeners;
-
-  /** Whether this object is currently observed by listeners or propagators. */
-  bool get isObserved() {
-    for (Observable obj = this; obj != null; obj = obj.parent) {
-      if (listeners.length > 0) {
-        return true;
-      }
-    }
-    return false;
-  }
-
-  AbstractObservable([Observable this.parent = null])
-    : uid = EventBatch.genUid(),
-      listeners = new List<ChangeListener>();
-
-  bool addChangeListener(ChangeListener listener) {
-    if (listeners.indexOf(listener, 0) == -1) {
-      listeners.add(listener);
-      return true;
-    }
-
-    return false;
-  }
-
-  bool removeChangeListener(ChangeListener listener) {
-    // TODO(rnystrom): This is awkward without List.remove(e).
-    if (listeners.indexOf(listener, 0) != -1) {
-      bool found = false;
-      listeners = listeners.filter((e) => found || !(found = (e == listener)));
-      return true;
-    } else {
-      return false;
-    }
-  }
-
-  void recordPropertyUpdate(String propertyName, newValue, oldValue) {
-    recordEvent(new ChangeEvent.property(
-        this, propertyName, newValue, oldValue));
-  }
-
-  void recordListUpdate(int index, newValue, oldValue) {
-    recordEvent(new ChangeEvent.list(
-        this, ChangeEvent.UPDATE, index, newValue, oldValue));
-  }
-
-  void recordListInsert(int index, newValue) {
-    recordEvent(new ChangeEvent.list(
-        this, ChangeEvent.INSERT, index, newValue, null));
-  }
-
-  void recordListRemove(int index, oldValue) {
-    recordEvent(new ChangeEvent.list(
-        this, ChangeEvent.REMOVE, index, null, oldValue));
-  }
-
-  void recordGlobalChange() {
-    recordEvent(new ChangeEvent.global(this));
-  }
-
-  void recordEvent(ChangeEvent event) {
-    // Bail if no one cares about the event.
-    if (!isObserved) {
-      return;
-    }
-
-    if (EventBatch.current != null) {
-      // Already in a batch, so just add it.
-      assert (!EventBatch.current.sealed);
-      // TODO(sigmund): measure the performance implications of this indirection
-      // and consider whether caching the summary object in this instance helps.
-      var summary = EventBatch.current.getEvents(this);
-      summary.addEvent(event);
-    } else {
-      // Not in a batch, so create a one-off one.
-      // TODO(rnystrom): Needing to do ignore and (null) here is awkward.
-      EventBatch.wrap((ignore) { recordEvent(event); })(null);
-    }
-  }
-}
-
-/** A growable list that fires events when it's modified. */
-class ObservableList<T>
-    extends AbstractObservable
-    implements List<T>, Observable {
-
-  /** Underlying list. */
-  // TODO(rnystrom): Make this final if we get list.remove().
-  List<T> _internal;
-
-  ObservableList([Observable parent = null])
-    : super(parent), _internal = new List<T>();
-
-  T operator [](int index) => _internal[index];
-
-  void operator []=(int index, T value) {
-    recordListUpdate(index, value, _internal[index]);
-    _internal[index] = value;
-  }
-
-  int get length() => _internal.length;
-
-  void set length(int value) {
-    _internal.length = value;
-    recordGlobalChange();
-  }
-
-  void clear() {
-    _internal.clear();
-    recordGlobalChange();
-  }
-
-  void sort(int compare(Object a, Object b)) {
-    _internal.sort(compare);
-    recordGlobalChange();
-  }
-
-  void add(T element) {
-    recordListInsert(length, element);
-    _internal.add(element);
-  }
-
-  void addLast(T element) {
-    add(element);
-  }
-
-  void addAll(Collection<T> elements) {
-    for (T element in elements) {
-      add(element);
-    }
-  }
-
-  int push(T element) {
-    recordListInsert(length, element);
-    _internal.add(element);
-    return _internal.length;
-  }
-
-  T last() => _internal.last();
-
-  T removeLast() {
-    final result = _internal.removeLast();
-    recordListRemove(length, result);
-    return result;
-  }
-
-  T removeAt(int index) {
-    int i = 0;
-    T found = null;
-    _internal = _internal.filter(bool _(element) {
-      if (i++ == index) {
-        found = element;
-        return false;
-      }
-      return true;
-    });
-    if (found != null) {
-      recordListRemove(index, found);
-    }
-    return found;
-  }
-
-  int indexOf(T element, [int start = 0]) {
-    return _internal.indexOf(element, start);
-  }
-
-  int lastIndexOf(T element, [int start = null]) {
-    if (start === null) start = length - 1;
-    return _internal.lastIndexOf(element, start);
-  }
-
-  bool removeFirstElement(T element) {
-    // the removeAt above will record the event.
-    return (removeAt(indexOf(element, 0)) != null);
-  }
-
-  int removeAllElements(T element) {
-    int count = 0;
-    for (int i = 0; i < length; i++) {
-      if (_internal[i] == element) {
-        // the removeAt above will record the event.
-        removeAt(i);
-        // adjust index since remove shifted elements.
-        i--;
-        count++;
-      }
-    }
-    return count;
-  }
-
-  void copyFrom(List<T> src, int srcStart, int dstStart, int count) {
-    Arrays.copy(src, srcStart, this, dstStart, count);
-  }
-
-  void setRange(int start, int length, List from, [int startFrom = 0]) {
-    throw const NotImplementedException();
-  }
-
-  void removeRange(int start, int length) {
-    throw const NotImplementedException();
-  }
-
-  void insertRange(int start, int length, [initialValue = null]) {
-    throw const NotImplementedException();
-  }
-
-  List getRange(int start, int length) {
-    throw const NotImplementedException();
-  }
-
-  // Iterable<T>:
-  Iterator<T> iterator() => _internal.iterator();
-
-  // Collection<T>:
-  Collection<T> filter(bool f(T element)) => _internal.filter(f);
-  Collection map(f(T element)) => _internal.map(f);
-  bool every(bool f(T element)) => _internal.every(f);
-  bool some(bool f(T element)) => _internal.some(f);
-  void forEach(void f(T element)) { _internal.forEach(f); }
-  bool isEmpty() => length == 0;
-}
-
-// TODO(jmesserly): is this too granular? Other similar systems make whole
-// classes observable instead of individual fields. The memory cost of having
-// every field effectively boxed, plus having a listeners list is likely too
-// much. Also, making a value observable necessitates adding ".value" to lots
-// of places, and constructing all fields with the verbose
-// "new ObservableValue<DataType>(myValue)".
-/** A wrapper around a single value whose change can be observed. */
-class ObservableValue<T> extends AbstractObservable {
-  ObservableValue(T value, [Observable parent = null])
-    : super(parent), _value = value;
-
-  T get value() => _value;
-
-  void set value(T newValue) {
-    // Only fire on an actual change.
-    // TODO(terry): An object identity test === is needed.  Each DataSource has
-    //              its own operator == which does a value compare.  Which
-    //              equality check should be done?
-    if (newValue !== _value) {
-      final oldValue = _value;
-      _value = newValue;
-      recordPropertyUpdate("value", newValue, oldValue);
-    }
-  }
-
-  T _value;
-}