!feat: Add CompositeEvent

This also breaks InteractBlockEvent.Secondary and SpawnEntityEvent.Pre

Author: gabizou

src/main/java/org/spongepowered/api/event/CompositeEvent.java

@@ -0,0 +1,51 @@
+package org.spongepowered.api.event;
+
+import org.spongepowered.api.util.annotation.eventgen.NoFactoryMethod;
+
+import java.util.List;
+import java.util.function.Consumer;
+
+/**
+ * A {@link CompositeEvent} is an {@link Event} that contains multiple
+ * side effectual {@link Event Events}, which may have their own side effects
+ * and may be {@link Cancellable}. In some cases, the interactions of this event
+ * may be cancellable as a whole, but are not guaranteed to revert all side
+ * effects on the {@link org.spongepowered.api.Game}. The {@link #children()} of
+ * this event are ordered in a "best-effort" basis, and may not be guaranteed
+ * to be in any particular order.
+ * <p>Using {@link #setCancelled(boolean)} will perform a best effort cancellation
+ * on each of the children events.
+ */
+@NoFactoryMethod
+public interface CompositeEvent<E extends Event> extends Event, Cancellable {
+
+    E baseEvent();
+
+    List<Event> children();
+
+    default <E extends Event> List<? extends E> event(Class<E> type) {
+        return this.children().stream()
+            .filter(type::isInstance)
+            .map(type::cast)
+            .toList();
+    }
+
+    default <E extends Event> void applyTo(Class<E> type, Consumer<? super E> consumer) {
+        this.children().stream()
+            .filter(type::isInstance)
+            .map(type::cast)
+            .forEach(consumer);
+    }
+
+    /**
+     * {@inheritDoc}
+     *
+     * Cancels this event and all related events captured {@link #children()}.
+     * Selectively, if individual events are wished to be cancelled,
+     * the individual events should be cancelled instead.
+     *
+     * @param cancel The new cancelled state
+     */
+    @Override
+    void setCancelled(boolean cancel);
+}

src/main/java/org/spongepowered/api/event/block/InteractBlockEvent.java

@@ -29,13 +29,18 @@
 import org.spongepowered.api.block.BlockTypes;
 import org.spongepowered.api.entity.living.player.Player;
 import org.spongepowered.api.event.Cancellable;
+import org.spongepowered.api.event.CompositeEvent;
 import org.spongepowered.api.event.action.InteractEvent;
+import org.spongepowered.api.event.entity.SpawnEntityEvent;
+import org.spongepowered.api.event.item.inventory.ChangeInventoryEvent;
 import org.spongepowered.api.item.inventory.ItemStack;
 import org.spongepowered.api.util.Direction;
 import org.spongepowered.api.util.Tristate;
 import org.spongepowered.api.world.server.ServerLocation;
 import org.spongepowered.math.vector.Vector3d;
 
+import java.util.Optional;
+
 /**
  * Base event for all interactions involving a {@link BlockSnapshot} at a
  * {@link ServerLocation}.
@@ -101,7 +106,7 @@ interface Finish extends Primary, Cancellable {
      *
      * <p>This is usually right-click.</p>
      */
-    interface Secondary extends InteractBlockEvent, Cancellable {
+    interface Secondary extends InteractBlockEvent {
 
         Tristate originalUseItemResult();
 
@@ -143,43 +148,47 @@ interface Secondary extends InteractBlockEvent, Cancellable {
          */
         Tristate useBlockResult();
 
-        /**
-         * Sets whether the {@link Player#itemInHand} should be used.
-         *
-         * <ul>
-         * <li>FALSE: The {@link ItemStack} will never be used.</li>
-         * <li>UNDEFINED: The {@link ItemStack} will be used if the block fails.
-         * </li>
-         * <li>TRUE: The {@link ItemStack} will always be used.</li>
-         * </ul>
-         *
-         * <p>Note: These results may differ depending on implementation.</p>
-         *
-         * @param result Whether the {@link Player#itemInHand} should be used
-         */
-        void setUseItemResult(Tristate result);
-
-        /**
-         * Sets whether the interacted {@link BlockSnapshot} should be used.
-         *
-         * <ul>
-         * <li>FALSE: {@link BlockSnapshot} will never be used.</li>
-         * <li>UNDEFINED: {@link BlockSnapshot} will be used as normal.</li>
-         * <li>TRUE: {@link BlockSnapshot} will always be used.</li>
-         * </ul>
-         *
-         * <p>Note: These results may differ depending on implementation.</p>
-         *
-         * @param result Whether the interacted {@link BlockSnapshot} should be
-         *     used
-         */
-        void setUseBlockResult(Tristate result);
-
         /**
          * Gets the point of interaction where the interaction occurred as a {@link Vector3d}.
          *
          * @return The interaction point
          */
         Vector3d interactionPoint();
+
+        interface Pre extends Secondary, Cancellable {
+
+            /**
+             * Sets whether the {@link Player#itemInHand} should be used.
+             *
+             * <ul>
+             * <li>FALSE: The {@link ItemStack} will never be used.</li>
+             * <li>UNDEFINED: The {@link ItemStack} will be used if the block fails.
+             * </li>
+             * <li>TRUE: The {@link ItemStack} will always be used.</li>
+             * </ul>
+             *
+             * <p>Note: These results may differ depending on implementation.</p>
+             *
+             * @param result Whether the {@link Player#itemInHand} should be used
+             */
+            void setUseItemResult(Tristate result);
+
+            /**
+             * Sets whether the interacted {@link BlockSnapshot} should be used.
+             *
+             * <ul>
+             * <li>FALSE: {@link BlockSnapshot} will never be used.</li>
+             * <li>UNDEFINED: {@link BlockSnapshot} will be used as normal.</li>
+             * <li>TRUE: {@link BlockSnapshot} will always be used.</li>
+             * </ul>
+             *
+             * <p>Note: These results may differ depending on implementation.</p>
+             *
+             * @param result Whether the interacted {@link BlockSnapshot} should be
+             *     used
+             */
+            void setUseBlockResult(Tristate result);
+        }
+
     }
 }

src/main/java/org/spongepowered/api/event/entity/SpawnEntityEvent.java

@@ -26,6 +26,7 @@
 
 import org.spongepowered.api.entity.Entity;
 import org.spongepowered.api.event.Cause;
+import org.spongepowered.api.event.impl.entity.AbstractAffectEntityEvent;
 import org.spongepowered.api.event.impl.entity.AbstractSpawnEntityEvent;
 import org.spongepowered.api.util.annotation.eventgen.GenerateFactoryMethod;
 import org.spongepowered.api.util.annotation.eventgen.ImplementedBy;
@@ -51,7 +52,8 @@ public interface SpawnEntityEvent extends AffectEntityEvent {
      * will result in no awareness to the client that the entity was being
      * spawned and later cancelled.
      */
-    interface Pre extends SpawnEntityEvent {}
+    @ImplementedBy(value = AbstractAffectEntityEvent.class, priority = 2)
+    interface Pre extends AffectEntityEvent {}
 
     interface Custom extends SpawnEntityEvent {}
 }