private PropertyChainEntry BuildChainEntry <T>(INotifyPropertyChanged observedInstance, PropertyChainEntry parent, PropertyInfo observedProperty, IEnumerable <PropertyInfo> remainingChain, Action <T, T> callback)
{
if (remainingChain == null || remainingChain.None())
{
return(BuildLastChainEntry(observedInstance, parent, observedProperty, callback));
}
var entry = new PropertyChainEntry(observedInstance, observedProperty, parent);
var nextInstance = GetNextInstance(observedInstance, observedProperty);
entry.NextEntry = BuildChainEntry(nextInstance, entry, remainingChain.First(), remainingChain.Skip(1).ToArray(), callback);
return(entry);
}
public PropertyChainEntry(INotifyPropertyChanged observedInstance, PropertyInfo observedProperty, PropertyChainEntry parent)
{
ObservedProperty = observedProperty;
ObservedInstance = observedInstance;
Parent = parent;
}
public LastPropertyChainEntry(INotifyPropertyChanged observedInstance, PropertyInfo observedProperty, PropertyChainEntry parent) :
base(observedInstance, observedProperty, parent)
{
_isInitialized = true;
}
private PropertyChainEntry BuildLastChainEntry <T>(INotifyPropertyChanged observedInstance, PropertyChainEntry parent, PropertyInfo observedProperty, Action <T, T> callback)
{
return(new LastPropertyChainEntry <T>(observedInstance, observedProperty, parent)
{
Callback = callback
});
}
private PropertyChainEntry BuildMiddleEntry(INotifyPropertyChanged observedInstance, PropertyChainEntry parent, PropertyInfo observedProperty)
{
return(new PropertyChainEntry(observedInstance, observedProperty, parent));
}
/// <summary>
/// Creates a listener that observes a property chain given by <paramref name="selectorExpression"/>
/// and rooted in <paramref name="rootObject"/>, invoking <paramref name="callback"/> on change
/// </summary>
/// <param name="rootObject">root of the property chain</param>
/// <param name="selectorExpression">expression pointing on a property to observe</param>
/// <param name="callback">callback to invoke when property changes; first argument to the callback is the old value of the observed property, second argument is the new value</param>
public PropertyChangedListener(TRoot rootObject, Expression <Func <TRoot, TProperty> > selectorExpression, Action <TProperty, TProperty> callback)
{
var memberChain = new MemberChainBuilder().BuildMemberChain(selectorExpression);
_listenerChain = new ListenerChainBuilder().BuildListenerChain(rootObject, memberChain, callback);
}