private PropertyPathBinding CreateBindingExpression(Expression expression)
{
List <BindingNode> bindingItems = new List <BindingNode>();
Expression currentExpression = expression;
BindingNode currentItem = null;
BindingNode nextItem = null;
while (currentExpression != null)
{
Type constructedType = typeof(BindingExpression <>).MakeGenericType(currentExpression.Type);
currentItem = new BindingNode(Activator.CreateInstance(constructedType, currentExpression) as IBindingExpression);
currentItem.Next = nextItem;
if (nextItem != null)
{
nextItem.Prev = currentItem;
}
nextItem = currentItem;
if (currentExpression.NodeType == ExpressionType.MemberAccess)
{
currentExpression = ((MemberExpression)currentExpression).Expression;
}
else
{
currentExpression = null;
}
}
return(new PropertyPathBinding(currentItem));
}
private BindingNode GetLastChild(BindingNode item)
{
if (item.Next != null)
{
return(GetLastChild(item.Next));
}
return(item);
}
public void Unsubscribe(BindingNode bindingItem)
{
var current = bindingItem;
while (current != null)
{
current.BindingExpression.Unsubscribe();
current = current.Next;
}
}
public PropertyPathBinding(BindingNode bindingItem)
{
BindingItem = bindingItem;
var lastChild = GetLastChild(bindingItem);
var expression = lastChild.BindingExpression.Expression;
if (lastChild.BindingExpression.Expression.NodeType == ExpressionType.MemberAccess)
{
propertyInfo = ((MemberExpression)expression).Member as PropertyInfo;
}
else
{
throw new NotSupportedException("Please provide property expression");
}
}
public bool TryGetValue(out object value)
{
value = null;
BindingNode current = BindingItem;
while (current != null)
{
value = current.BindingExpression.Value;
if (value == null)
{
return(current.Next != null ? false : true);
}
current = current.Next;
}
return(true);
}
public bool TrySetValue(object value)
{
bool result = false;
BindingNode current = BindingItem;
while (current != null)
{
// that will be the target of Last property of the path
if (current.Next?.Next == null)
{
var target = current.BindingExpression.Value;
if (target != null)
{
if ((value == null && current.Next.BindingExpression.Value != null) ||
value != null && value.Equals(current.Next.BindingExpression.Value) == false)
{
propertyInfo.SetValue(target, value, null);
}
result = true;
}
else
{
result = false;
}
break;
}
else
{
if (current.BindingExpression.Value == null)
{
return(false);
}
}
current = current.Next;
}
return(result);
}
private void Subscribe(BindingNode bindingItem, Action action)
{
var current = bindingItem;
BindingNode prev = null;
while (current != null)
{
var innerCurrent = current;
current.BindingExpression.Subscribe(prev?.BindingExpression?.Value, () =>
{
action();
// if that is leaf property dont resubscribe
if (innerCurrent?.Next != null)
{
Unsubscribe(innerCurrent);
Subscribe(innerCurrent, action);
}
});
prev = current;
current = current.Next;
}
}
