private bool EvalBindingHooks <TViewModel, TView>(TViewModel viewModel, TView view, Expression vmExpression, Expression viewExpression, BindingDirection direction)
where TViewModel : class
{
var hooks = Locator.Current.GetServices <IPropertyBindingHook>();
var vmFetcher = default(Func <IObservedChange <object, object>[]>);
if (vmExpression != null)
{
vmFetcher = () =>
{
IObservedChange <object, object>[] fetchedValues;
Reflection.TryGetAllValuesForPropertyChain(out fetchedValues, viewModel, vmExpression.GetExpressionChain());
return(fetchedValues);
};
}
else
{
vmFetcher = () =>
{
return(new[]
{
new ObservedChange <object, object>(null, null, viewModel)
});
};
}
var vFetcher = new Func <IObservedChange <object, object>[]>(() =>
{
IObservedChange <object, object>[] fetchedValues;
Reflection.TryGetAllValuesForPropertyChain(out fetchedValues, view, viewExpression.GetExpressionChain());
return(fetchedValues);
});
var shouldBind = hooks.Aggregate(true, (acc, x) =>
acc && x.ExecuteHook(viewModel, view, vmFetcher, vFetcher, direction));
if (!shouldBind)
{
var vmString = $"{typeof(TViewModel).Name}.{string.Join(".", vmExpression)}";
var vString = $"{typeof(TView).Name}.{string.Join(".", viewExpression)}";
this.Log().Warn("Binding hook asked to disable binding {0} => {1}", vmString, vString);
}
return(shouldBind);
}
