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package model;
import annotations.Assoc;
import java.util.HashMap;
import java.util.Map;
/**
* A group of observers with different types registered.
*/
public class GroupObserver implements Observer {
/**
* The map. Because Java doesn't have dependent maps, they are left here as unchecked.
*/
@Assoc(partOf = true)
private final Map<Class, Observer> map = new HashMap<>();
/**
* EFFECTS: Register a data type with an observer. Override existing registrations with the same type.
* REQUIRES: cls != null, obs != null.
*/
public <T> void register(Class<T> cls, Observer<T> obs) {
map.put(cls, obs);
}
/**
* EFFECTS: Notify the registered observer based on the type of 'o' with given arguments.
* Does nothing if no registration found. Subclasses are supported as long as a parent class observer is registered.
* Specific type match takes priority. Non-specific type match is not guaranteed to be the closest.
* REQUIRES: o != null, direction be DIRECTION_*, index >= 0 or == INDEX_NOT_IN_LIST.
*/
@Override
public void accept(Object o, int direction, int i) {
Observer obs = map.get(o.getClass());
if (obs == null) {
Class supertype = map.keySet().stream().filter(clz -> clz.isInstance(o)).findFirst().orElse(null);
if (supertype == null) {
return;
}
obs = map.get(supertype);
}
obs.accept(o, direction, i);
}
/**
* EFFECTS: Count the observers.
*/
public int getRegisteredObserverCount() {
return map.size();
}
}
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