private void EndObserveDependency(Dependency dependency) {
if (dependency.Target == null)
return;
dependency.Target.PropertyChanged -= dependency.Handler;
dependency.SubDependencies.ForEach(this.EndObserveDependency);
}
private void BeginObserveDependency(Dependency dependency) {
dependency.UpdateTarget();
Require.NotNull<BindingException>(dependency.Target, dependency.PropertyName);
dependency.Handler = this.OnDependencyValueChanged(dependency);
dependency.Target.PropertyChanged += dependency.Handler;
dependency.SubDependencies.ForEach(this.BeginObserveDependency);
}
public DependencyWatcher(
Dependency[] dependencies,
BindingMode mode,
BindindErrorOptions errorOptions
) {
_dependencies = dependencies;
_mode = mode;
_errorOptions = errorOptions;
}
private PropertyChangedEventHandler OnDependencyValueChanged(Dependency dependency) {
return (sender, args) => {
if (dependency.PropertyName != args.PropertyName)
return;
this.Protect(() => {
this.UpdateHandlers(dependency);
this.ValueChanged(this, EventArgs.Empty);
});
};
}
protected override Expression VisitMember(MemberExpression node)
{
if (!(node.Member is PropertyInfo))
return base.VisitMember(node);
if (!node.Expression.Type.Implements<INotifyPropertyChanged>())
return base.VisitMember(node);
var dependency = new Dependency(node.Expression, node.Member.Name);
dependency.SubDependencies.AddRange(_dependencies);
_dependencies = new[] { dependency };
return base.VisitMember(node);
}
private IDisposable PushChildDependencies(Dependency dependency)
{
_childDependencies.Push(dependency);
return Disposable.Create(() => _childDependencies.Pop());
}
private Dependency AddDependency(Expression expression, string propertyName)
{
var dependency = new Dependency(expression, propertyName);
dependency.SubDependencies.AddRange(this._childDependencies);
_dependencies.Add(dependency);
return dependency;
}
private void UpdateHandlers(Dependency dependency) {
dependency.SubDependencies.ForEach(this.EndObserveDependency);
dependency.SubDependencies.ForEach(this.BeginObserveDependency);
}
