public bool RegisterSelector <TReturn>(string name, Func <TState, TReturn> selector, SelectorCallback <TReturn> valueChangedCallback)
{
return(Selectors <TReturn> .RegisterSelector(this, name, selector, valueChangedCallback));
}
public StoreBuilder <TState> WithSelector <TReturn>(string name, Func <TState, TReturn> selector, SelectorCallback <TReturn> valueChangedCallback)
{
store.RegisterSelector(name, selector, valueChangedCallback);
return(this);
}
internal static bool RegisterSelector(Store <TState> store, string name, Func <TState, TReturn> selector, SelectorCallback <TReturn> valueChangedCallback)
{
if (selector == null)
{
return(false);
}
var selectorDictionary = SelectorDictionary.GetOrAdd(store, (a) => new ConcurrentDictionary <string, Func <TState, TReturn> >());
var selectorReturnValues = SelectorReturnValues.GetOrAdd(store, (a) => new ConcurrentDictionary <string, TReturn>());
selectorDictionary[name] = (state) =>
{
try
{
return(selector(state));
}
catch (Exception)
{
return(default(TReturn));
}
};
selectorReturnValues[name] = selectorDictionary[name](store.State);
void handler(object sender, StateChangeEventArgs <TState> eventArgs)
{
var newValue = selectorDictionary[name](eventArgs.NewState);
var previousValue = selectorReturnValues[name];
if (!EqualityComparer <TReturn> .Default.Equals(newValue, previousValue))
{
selectorReturnValues[name] = newValue;
try
{
valueChangedCallback?.Invoke(previousValue, newValue);
}
catch (Exception)
{
valueChangedCallback = null;
}
}
}
store.StateChanged += handler;
return(true);
}