Add core:qsl_base

Author: OroArmor

fabric-api-base/build.gradle

@@ -5,3 +5,7 @@ testDependencies(project, [
 	':fabric-lifecycle-events-v1',
 	':fabric-screen-api-v1'
 ])
+
+dependencies {
+	modApi getQslModule("core", "qsl_base")
+}

fabric-api-base/src/main/java/net/fabricmc/fabric/impl/base/event/QuiltCompatEvent.java

@@ -0,0 +1,78 @@
+/*
+ * Copyright 2022 The Quilt Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package net.fabricmc.fabric.impl.base.event;
+
+import java.util.function.Function;
+import java.util.function.Supplier;
+
+import net.minecraft.util.Identifier;
+
+import net.fabricmc.fabric.api.event.Event;
+
+/**
+ * Allows for the translation of events from Quilt to Fabric.
+ */
+public final class QuiltCompatEvent {
+	private QuiltCompatEvent() {
+	}
+
+	/**
+	 * Creates a new Fabric event that delegates to a Quilt Event.
+	 *
+	 * @param event the Quilt event
+	 * @param listenerConverter a function that converts a Fabric listener to a Quilt listener
+	 * @param invoker a function that converts a Quilt listener to a Fabric listener
+	 * @param <S> the Quilt event listener type
+	 * @param <D> the Fabric event listener type
+	 * @return a Fabric event wrapping the Quilt event
+	 */
+	public static <S, D> Event<D> fromQuilt(org.quiltmc.qsl.base.api.event.Event<S> event,
+											Function<D, S> listenerConverter, Function<Supplier<S>, D> invoker) {
+		return new QuiltEvent<>(event, listenerConverter, invoker);
+	}
+
+	public static final class QuiltEvent<S, D> extends Event<D> {
+		private final org.quiltmc.qsl.base.api.event.Event<S> event;
+		private final Function<D, S> listenerConverter;
+
+		public QuiltEvent(org.quiltmc.qsl.base.api.event.Event<S> event, Function<D, S> listenerConverter, Function<Supplier<S>, D> invoker) {
+			this.event = event;
+			this.listenerConverter = listenerConverter;
+			this.invoker = invoker.apply(event::invoker);
+		}
+
+		@Override
+		public void register(D listener) {
+			this.event.register(this.listenerConverter.apply(listener));
+		}
+
+		@Override
+		public void register(Identifier phase, D listener) {
+			this.event.register(quiltifyPhases(phase), this.listenerConverter.apply(listener));
+		}
+
+		@Override
+		public void addPhaseOrdering(Identifier firstPhase, Identifier secondPhase) {
+			this.event.addPhaseOrdering(quiltifyPhases(firstPhase), quiltifyPhases(secondPhase));
+		}
+
+		// This makes Fabric's default phase equal to the Quilt one, preventing ordering issues
+		private static Identifier quiltifyPhases(Identifier phase) {
+			return phase.equals(DEFAULT_PHASE) ? org.quiltmc.qsl.base.api.event.Event.DEFAULT_PHASE : phase;
+		}
+	}
+}