/// <summary>
/// Binds the specified <see cref="PropertyChangedEventHandler"/> on _all_ observables (including via <see cref="INotifyCollectionChanged"/>)
/// reachable via reflection that have a property with the specified name and type, and invokes the handler on those event that match the predicate.
/// </summary>
public static IDisposable BindRecursively <TPropertyType>(this INotifyPropertyChanged root,
string propertyName,
PropertyMutatedEventHandler <TPropertyType> handler)
{
return(root.BindRecursively(predicate, handlerWrapper));
bool predicate(object obj, IPropertyMutatedEventArgs e)
{
if (e.PropertyName == propertyName)
{
var propertyType = GetPropertyType(obj.GetType(), propertyName);
var result = typeof(TPropertyType).IsAssignableFrom(propertyType);
return(result);
}
return(false);
}
void handlerWrapper(object sender, IPropertyMutatedEventArgs e)
{
handler(sender, (PropertyMutatedEventArgs <TPropertyType>)e);
}
}
/// <summary>
/// Binds the specified <see cref="PropertyChangedEventHandler"/> on _all_ observables (including via <see cref="INotifyCollectionChanged"/>)
/// reachable via reflection, and invokes the handler on those event that match the predicate.
/// </summary>
/// <param name="predicate"> A predicate for invoking the handler. (not a predicate for hooking the handler). </param>
public static IDisposable BindRecursively(this INotifyPropertyChanged root,
Func <object, IPropertyMutatedEventArgs, bool> predicate,
PropertyMutatedEventHandler handler)
{
Contract.Requires(root != null);
Contract.Requires(predicate != null);
Contract.Requires(handler != null);
var allHookedObservables = new Dictionary <object, int>(ReferenceEqualityComparer.Instance); // integer is reference counts by this dictionary
addReference(root);
#if DEBUG
return(new BindRecursivelyDisposable(allHookedObservables, () =>
#else
return new Disposable(() =>
#endif
{
foreach (var obj in allHookedObservables)
{
unhook(obj);
}
allHookedObservables.Clear();
}));
void hook(object tree)
{
foreach (object obj in getEntireObjectTree(tree))
{
var deltaReferenceCount = 0;
if (obj is INotifyPropertyChanged container)
{
container.PropertyChanged += handle;
deltaReferenceCount++;
}
if (obj is INotifyCollectionChanged collection)
{
collection.CollectionChanged += handleCollectionChanged;
deltaReferenceCount++;
}
if (deltaReferenceCount != 0)
{
allHookedObservables[obj] = allHookedObservables.GetOrAdd(obj, 0) + deltaReferenceCount;
}
}
}
void unhook(object tree)
{
Contract.Assume(allHookedObservables.ContainsKey(tree));
foreach (object obj in getEntireObjectTree(tree))
{
var deltaReferenceCount = 0;
if (obj is INotifyPropertyChanged container)
{
container.PropertyChanged -= handle;
deltaReferenceCount--;
}
if (obj is INotifyCollectionChanged collection)
{
collection.CollectionChanged -= handleCollectionChanged;
deltaReferenceCount--;
}
if (deltaReferenceCount != 0)
{
allHookedObservables[obj] += deltaReferenceCount;
}
}
}
void addReference(object newReferredObject)
{
if (newReferredObject != null && allHookedObservables.ContainsKey(newReferredObject))
{
allHookedObservables[newReferredObject]++;
}
else
{
hook(newReferredObject);
}
}
void removeReference(object oldReferredObject)
{
if (oldReferredObject != null && allHookedObservables.ContainsKey(oldReferredObject))
{
if (--allHookedObservables[oldReferredObject] == 0)
{
unhook(oldReferredObject);
}
}
}
void updateReferences(object oldReferredObject, object newReferredObject)
{
if (ReferenceEquals(oldReferredObject, newReferredObject))
{
return;
}
addReference(newReferredObject);
removeReference(oldReferredObject);
}
void handle(object sender, PropertyChangedEventArgs originalE)
{
if (originalE is IPropertyMutatedEventArgs e)
{
updateReferences(e.OldValue, e.NewValue);
if (predicate(sender, e))
{
handler.Invoke(sender, e);
}
}
}
void handleCollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
{
switch (e.Action)
{
case NotifyCollectionChangedAction.Add:
foreach (var newObj in e.NewItems)
{
addReference(newObj);
}
break;
case NotifyCollectionChangedAction.Reset:
case NotifyCollectionChangedAction.Remove:
foreach (var newObj in e.OldItems)
{
removeReference(newObj);
}
break;
case NotifyCollectionChangedAction.Replace:
foreach (var newObj in e.NewItems)
{
addReference(newObj);
}
foreach (var newObj in e.OldItems)
{
removeReference(newObj);
}
break;
case NotifyCollectionChangedAction.Move:
break;
default:
throw new InvalidOperationException();
}
}
}
/// <summary> Invokes the specified handler when a property on a property changes, or when the source changes,
/// and, if the current value differs from the specified default value, at the end of this call. </summary>
/// <param name="propertyName"> The name of the property on the source. </param>
/// <param name="propertyOnPropertyName"> The name of the property on the property on the source. </param>
/// <param name="handler"> The handler to be invoked at the moments listed above. </param>
/// <param name="defaultValue"> The value that is the default of the property on the property (used as old value when the property containing that property is null). </param>
public static void Bind <T>(this INotifyPropertyChanged source, string propertyName, string propertyOnPropertyName, PropertyMutatedEventHandler <T> handler, T defaultValue)
{
Bind(source, propertyName, propertyOnPropertyName, (sender, e) => handler(sender, (PropertyMutatedEventArgs <T>)e), defaultValue, typeof(T));
}
/// <summary> Invokes the specified handler when a property on a property changes, or when the source changes,
/// and, if the current value differs from the default value, at the end of this call. </summary>
/// <param name="propertyName"> The name of the property on the source. </param>
/// <param name="propertyOnPropertyName"> The name of the property on the property on the source. </param>
/// <param name="handler"> The handler to be invoked at the moments listed above. </param>
public static void Bind <T>(this INotifyPropertyChanged source, string propertyName, string propertyOnPropertyName, PropertyMutatedEventHandler <T> handler)
{
// this overload makes use of the feature of the other overload to correct the default value if it is null to the default
Bind(source, propertyName, propertyOnPropertyName, (sender, e) => handler(sender, (PropertyMutatedEventArgs <T>)e), null);
}
