155 lines
3.9 KiB
Java
155 lines
3.9 KiB
Java
package net.minecraftforge.event;
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import static java.lang.annotation.ElementType.TYPE;
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import static java.lang.annotation.RetentionPolicy.RUNTIME;
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import java.lang.annotation.Retention;
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import java.lang.annotation.Target;
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import java.util.Map;
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import java.util.concurrent.ConcurrentHashMap;
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/**
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* Base Event class that all other events are derived from
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*/
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public class Event
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{
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@Retention(value = RUNTIME)
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@Target(value = TYPE)
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public @interface HasResult{}
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public enum Result
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{
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DENY,
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DEFAULT,
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ALLOW
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}
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private boolean isCanceled = false;
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private final boolean isCancelable;
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private Result result = Result.DEFAULT;
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private final boolean hasResult;
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private static ListenerList listeners = new ListenerList();
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private static final Map<Class, Map<Class, Boolean>> annotationMap = new ConcurrentHashMap<Class, Map<Class, Boolean>>();
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public Event()
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{
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setup();
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isCancelable = hasAnnotation(Cancelable.class);
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hasResult = hasAnnotation(HasResult.class);
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}
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private boolean hasAnnotation(Class annotation)
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{
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Class me = this.getClass();
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Map<Class, Boolean> list = annotationMap.get(me);
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if (list == null)
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{
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list = new ConcurrentHashMap<Class, Boolean>();
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annotationMap.put(me, list);
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}
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Boolean cached = list.get(annotation);
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if (cached != null)
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{
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return cached;
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}
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Class cls = me;
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while (cls != Event.class)
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{
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if (cls.isAnnotationPresent(annotation))
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{
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list.put(annotation, true);
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return true;
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}
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cls = cls.getSuperclass();
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}
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list.put(annotation, false);
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return false;
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}
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/**
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* Determine if this function is cancelable at all.
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* @return If access to setCanceled should be allowed
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*/
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public boolean isCancelable()
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{
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return isCancelable;
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}
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/**
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* Determine if this event is canceled and should stop executing.
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* @return The current canceled state
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*/
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public boolean isCanceled()
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{
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return isCanceled;
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}
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/**
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* Sets the state of this event, not all events are cancelable, and any attempt to
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* cancel a event that can't be will result in a IllegalArgumentException.
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*
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* The functionality of setting the canceled state is defined on a per-event bases.
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*
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* @param cancel The new canceled value
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*/
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public void setCanceled(boolean cancel)
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{
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if (!isCancelable())
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{
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throw new IllegalArgumentException("Attempted to cancel a uncancelable event");
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}
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isCanceled = cancel;
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}
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/**
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* Determines if this event expects a significant result value.
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*/
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public boolean hasResult()
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{
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return hasResult;
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}
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/**
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* Returns the value set as the result of this event
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*/
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public Result getResult()
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{
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return result;
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}
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/**
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* Sets the result value for this event, not all events can have a result set, and any attempt to
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* set a result for a event that isn't expecting it will result in a IllegalArgumentException.
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*
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* The functionality of setting the result is defined on a per-event bases.
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*
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* @param value The new result
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*/
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public void setResult(Result value)
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{
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result = value;
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}
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/**
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* Called by the base constructor, this is used by ASM generated
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* event classes to setup various functionality such as the listener's list.
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*/
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protected void setup()
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{
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}
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/**
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* Returns a ListenerList object that contains all listeners
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* that are registered to this event.
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*
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* @return Listener List
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*/
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public ListenerList getListenerList()
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{
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return listeners;
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}
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}
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