Merge pull request #247 from PolyhedralDev/dev/functionalevents

Abstract event system with functional default implementation

common/addons/biome-provider-pipeline/src/main/java/com/dfsek/terra/addons/biome/pipeline/BiomePipelineAddon.java

@@ -25,8 +25,8 @@ import com.dfsek.terra.api.addon.TerraAddon;
 import com.dfsek.terra.api.addon.annotations.Addon;
 import com.dfsek.terra.api.addon.annotations.Author;
 import com.dfsek.terra.api.addon.annotations.Version;
-import com.dfsek.terra.api.event.EventListener;
 import com.dfsek.terra.api.event.events.config.pack.ConfigPackPreLoadEvent;
+import com.dfsek.terra.api.event.functional.FunctionalEventHandler;
 import com.dfsek.terra.api.injection.annotations.Inject;
 import com.dfsek.terra.api.util.reflection.TypeKey;
 import com.dfsek.terra.api.world.biome.generation.BiomeProvider;
@@ -35,7 +35,7 @@ import com.dfsek.terra.api.world.biome.generation.pipeline.BiomeSource;
 @Addon("biome-provider-pipeline")
 @Author("Terra")
 @Version("1.0.0")
-public class BiomePipelineAddon extends TerraAddon implements EventListener {
+public class BiomePipelineAddon extends TerraAddon {
     @Inject
     private TerraPlugin main;
 
@@ -44,11 +44,10 @@ public class BiomePipelineAddon extends TerraAddon implements EventListener {
 
     @Override
     public void initialize() {
-        main.getEventManager().registerListener(this, this);
+        main.getEventManager()
-    }
+                .getHandler(FunctionalEventHandler.class)
-
+                .register(this, ConfigPackPreLoadEvent.class)
-    public void onPackLoad(ConfigPackPreLoadEvent event) {
+                .then(event -> event.getPack().applyLoader(BIOME_SOURCE_BUILDER_TOKEN.getType(), new SourceLoader())
-        event.getPack().applyLoader(BIOME_SOURCE_BUILDER_TOKEN.getType(), new SourceLoader())
                         .applyLoader(Stage.class, new StageLoader())
                         .applyLoader(ExpanderStage.Type.class, (c, o, l) -> ExpanderStage.Type.valueOf((String) o))
                         .applyLoader(MutatorStage.Type.class, (c, o, l) -> MutatorStage.Type.valueOf((String) o))
@@ -60,6 +59,7 @@ public class BiomePipelineAddon extends TerraAddon implements EventListener {
                         .applyLoader(SmoothMutator.class, SmoothMutatorTemplate::new)
                         .applyLoader(ExpanderStage.class, ExpanderStageTemplate::new)
                         .applyLoader(BiomePipelineProvider.class, () -> new BiomePipelineTemplate(main))
-                .applyLoader(BIOME_PROVIDER_BUILDER_TOKEN.getType(), new BiomeProviderLoader());
+                        .applyLoader(BIOME_PROVIDER_BUILDER_TOKEN.getType(), new BiomeProviderLoader()))
+                .failThrough();
     }
 }

common/addons/chunk-generator-noise-3d/src/main/java/com/dfsek/terra/addons/chunkgenerator/NoiseChunkGenerator3DAddon.java

@@ -10,35 +10,41 @@ import com.dfsek.terra.api.addon.TerraAddon;
 import com.dfsek.terra.api.addon.annotations.Addon;
 import com.dfsek.terra.api.addon.annotations.Author;
 import com.dfsek.terra.api.addon.annotations.Version;
-import com.dfsek.terra.api.event.EventListener;
 import com.dfsek.terra.api.event.events.config.ConfigurationLoadEvent;
 import com.dfsek.terra.api.event.events.config.pack.ConfigPackPreLoadEvent;
+import com.dfsek.terra.api.event.functional.FunctionalEventHandler;
 import com.dfsek.terra.api.injection.annotations.Inject;
-import com.dfsek.terra.api.registry.exception.DuplicateEntryException;
 import com.dfsek.terra.api.world.biome.TerraBiome;
 import com.dfsek.terra.api.world.generator.ChunkGeneratorProvider;
 
 @Addon("chunk-generator-noise-3d")
 @Author("Terra")
 @Version("1.0.0")
-public class NoiseChunkGenerator3DAddon extends TerraAddon implements EventListener {
+public class NoiseChunkGenerator3DAddon extends TerraAddon {
     @Inject
     private TerraPlugin main;
 
     @Override
     public void initialize() {
-        main.getEventManager().registerListener(this, this);
+        main.getEventManager()
-    }
+                .getHandler(FunctionalEventHandler.class)
-
+                .register(this, ConfigPackPreLoadEvent.class)
-    public void onPackLoad(ConfigPackPreLoadEvent event) throws DuplicateEntryException {
+                .then(event -> {
                     event.getPack().getOrCreateRegistry(ChunkGeneratorProvider.class).register("NOISE_3D", pack -> new NoiseChunkGenerator3D(pack, main));
-        event.getPack().applyLoader(SlantHolder.class, new SlantHolderLoader())
+                    event.getPack()
+                            .applyLoader(SlantHolder.class, new SlantHolderLoader())
                             .applyLoader(PaletteHolder.class, new PaletteHolderLoader());
-    }
+                })
+                .failThrough();
 
-    public void onBiomeLoad(ConfigurationLoadEvent event) {
+        main.getEventManager()
+                .getHandler(FunctionalEventHandler.class)
+                .register(this, ConfigurationLoadEvent.class)
+                .then(event -> {
                     if(event.is(TerraBiome.class)) {
                         event.getLoadedObject(TerraBiome.class).getContext().put(event.load(new BiomePaletteTemplate()).get());
                     }
+                })
+                .failThrough();
     }
 }

common/addons/config-biome/src/main/java/com/dfsek/terra/addons/biome/BiomeAddon.java

@@ -7,24 +7,26 @@ import com.dfsek.terra.api.addon.TerraAddon;
 import com.dfsek.terra.api.addon.annotations.Addon;
 import com.dfsek.terra.api.addon.annotations.Author;
 import com.dfsek.terra.api.addon.annotations.Version;
-import com.dfsek.terra.api.event.EventListener;
 import com.dfsek.terra.api.event.events.config.pack.ConfigPackPreLoadEvent;
+import com.dfsek.terra.api.event.functional.FunctionalEventHandler;
 import com.dfsek.terra.api.injection.annotations.Inject;
 
 @Addon("config-biome")
 @Author("Terra")
 @Version("1.0.0")
-public class BiomeAddon extends TerraAddon implements EventListener {
+public class BiomeAddon extends TerraAddon {
     @Inject
     private TerraPlugin main;
 
     @Override
     public void initialize() {
-        main.getEventManager().registerListener(this, this);
+        main.getEventManager()
-    }
+                .getHandler(FunctionalEventHandler.class)
-
+                .register(this, ConfigPackPreLoadEvent.class)
-    public void onPackLoad(ConfigPackPreLoadEvent event) {
+                .then(event -> {
                     event.getPack().registerConfigType(new BiomeConfigType(event.getPack()), "BIOME", 5);
                     event.getPack().applyLoader(PaletteHolder.class, new PaletteHolderLoader());
+                })
+                .failThrough();
     }
 }

common/addons/config-distributors/src/main/java/com/dfsek/terra/addons/feature/distributor/DistributorAddon.java

@@ -10,8 +10,8 @@ import com.dfsek.terra.api.addon.TerraAddon;
 import com.dfsek.terra.api.addon.annotations.Addon;
 import com.dfsek.terra.api.addon.annotations.Author;
 import com.dfsek.terra.api.addon.annotations.Version;
-import com.dfsek.terra.api.event.EventListener;
 import com.dfsek.terra.api.event.events.config.pack.ConfigPackPreLoadEvent;
+import com.dfsek.terra.api.event.functional.FunctionalEventHandler;
 import com.dfsek.terra.api.injection.annotations.Inject;
 import com.dfsek.terra.api.registry.CheckedRegistry;
 import com.dfsek.terra.api.structure.feature.Distributor;
@@ -22,23 +22,24 @@ import java.util.function.Supplier;
 @Addon("config-distributors")
 @Version("1.0.0")
 @Author("Terra")
-public class DistributorAddon extends TerraAddon implements EventListener {
+public class DistributorAddon extends TerraAddon {
     public static final TypeKey<Supplier<ObjectTemplate<Distributor>>> DISTRIBUTOR_TOKEN = new TypeKey<>() {};
     @Inject
     private TerraPlugin main;
 
     @Override
     public void initialize() {
-        main.getEventManager().registerListener(this, this);
+        main.getEventManager()
-    }
+                .getHandler(FunctionalEventHandler.class)
-
+                .register(this, ConfigPackPreLoadEvent.class)
-
+                .then(event -> {
-    public void packPreLoad(ConfigPackPreLoadEvent event) {
                     CheckedRegistry<Supplier<ObjectTemplate<Distributor>>> distributorRegistry = event.getPack().getOrCreateRegistry(DISTRIBUTOR_TOKEN);
                     distributorRegistry.register("NOISE", NoiseDistributorTemplate::new);
                     distributorRegistry.register("POINTS", PointSetDistributorTemplate::new);
 
                     event.getPack()
                             .applyLoader(Point.class, PointTemplate::new);
+                })
+                .failThrough();
     }
 }

common/addons/config-feature/src/main/java/com/dfsek/terra/addons/feature/FeatureAddon.java

@@ -5,23 +5,23 @@ import com.dfsek.terra.api.addon.TerraAddon;
 import com.dfsek.terra.api.addon.annotations.Addon;
 import com.dfsek.terra.api.addon.annotations.Author;
 import com.dfsek.terra.api.addon.annotations.Version;
-import com.dfsek.terra.api.event.EventListener;
 import com.dfsek.terra.api.event.events.config.pack.ConfigPackPreLoadEvent;
+import com.dfsek.terra.api.event.functional.FunctionalEventHandler;
 import com.dfsek.terra.api.injection.annotations.Inject;
 
 @Addon("config-feature")
 @Version("1.0.0")
 @Author("Terra")
-public class FeatureAddon extends TerraAddon implements EventListener {
+public class FeatureAddon extends TerraAddon {
     @Inject
     private TerraPlugin main;
 
     @Override
     public void initialize() {
-        main.getEventManager().registerListener(this, this);
+        main.getEventManager()
-    }
+                .getHandler(FunctionalEventHandler.class)
-
+                .register(this, ConfigPackPreLoadEvent.class)
-    public void onPackLoad(ConfigPackPreLoadEvent event) {
+                .then(event -> event.getPack().registerConfigType(new FeatureConfigType(), "FEATURE", 2))
-        event.getPack().registerConfigType(new FeatureConfigType(), "FEATURE", 2);
+                .failThrough();
     }
 }

common/addons/config-flora/src/main/java/com/dfsek/terra/addons/flora/FloraAddon.java

@@ -7,25 +7,26 @@ import com.dfsek.terra.api.addon.TerraAddon;
 import com.dfsek.terra.api.addon.annotations.Addon;
 import com.dfsek.terra.api.addon.annotations.Author;
 import com.dfsek.terra.api.addon.annotations.Version;
-import com.dfsek.terra.api.event.EventListener;
 import com.dfsek.terra.api.event.events.config.pack.ConfigPackPreLoadEvent;
+import com.dfsek.terra.api.event.functional.FunctionalEventHandler;
 import com.dfsek.terra.api.injection.annotations.Inject;
-import com.dfsek.terra.api.registry.exception.DuplicateEntryException;
 
 @Addon("config-flora")
 @Author("Terra")
 @Version("0.1.0")
-public class FloraAddon extends TerraAddon implements EventListener {
+public class FloraAddon extends TerraAddon {
     @Inject
     private TerraPlugin main;
 
     @Override
     public void initialize() {
-        main.getEventManager().registerListener(this, this);
+        main.getEventManager()
-    }
+                .getHandler(FunctionalEventHandler.class)
-
+                .register(this, ConfigPackPreLoadEvent.class)
-    public void onPackLoad(ConfigPackPreLoadEvent event) throws DuplicateEntryException {
+                .then(event -> {
                     event.getPack().registerConfigType(new FloraConfigType(), "FLORA", 2);
                     event.getPack().applyLoader(BlockLayer.class, BlockLayerTemplate::new);
+                })
+                .failThrough();
     }
 }

common/addons/config-locators/src/main/java/com/dfsek/terra/addons/feature/locator/LocatorAddon.java

@@ -8,8 +8,8 @@ import com.dfsek.terra.api.addon.TerraAddon;
 import com.dfsek.terra.api.addon.annotations.Addon;
 import com.dfsek.terra.api.addon.annotations.Author;
 import com.dfsek.terra.api.addon.annotations.Version;
-import com.dfsek.terra.api.event.EventListener;
 import com.dfsek.terra.api.event.events.config.pack.ConfigPackPreLoadEvent;
+import com.dfsek.terra.api.event.functional.FunctionalEventHandler;
 import com.dfsek.terra.api.injection.annotations.Inject;
 import com.dfsek.terra.api.registry.CheckedRegistry;
 import com.dfsek.terra.api.structure.feature.Locator;
@@ -20,7 +20,7 @@ import java.util.function.Supplier;
 @Addon("config-locators")
 @Version("1.0.0")
 @Author("Terra")
-public class LocatorAddon extends TerraAddon implements EventListener {
+public class LocatorAddon extends TerraAddon {
 
     public static final TypeKey<Supplier<ObjectTemplate<Locator>>> LOCATOR_TOKEN = new TypeKey<>() {};
     @Inject
@@ -28,12 +28,14 @@ public class LocatorAddon extends TerraAddon implements EventListener {
 
     @Override
     public void initialize() {
-        main.getEventManager().registerListener(this, this);
+        main.getEventManager()
-    }
+                .getHandler(FunctionalEventHandler.class)
-
+                .register(this, ConfigPackPreLoadEvent.class)
-    public void onPackLoad(ConfigPackPreLoadEvent event) {
+                .then(event -> {
                     CheckedRegistry<Supplier<ObjectTemplate<Locator>>> locatorRegistry = event.getPack().getOrCreateRegistry(LOCATOR_TOKEN);
                     locatorRegistry.register("SURFACE", () -> new SurfaceLocatorTemplate(main));
                     locatorRegistry.register("RANDOM", RandomLocatorTemplate::new);
+                })
+                .failThrough();
     }
 }

common/addons/config-noise-function/src/main/java/com/dfsek/terra/addons/noise/NoiseAddon.java

@@ -30,8 +30,8 @@ import com.dfsek.terra.api.addon.TerraAddon;
 import com.dfsek.terra.api.addon.annotations.Addon;
 import com.dfsek.terra.api.addon.annotations.Author;
 import com.dfsek.terra.api.addon.annotations.Version;
-import com.dfsek.terra.api.event.EventListener;
 import com.dfsek.terra.api.event.events.config.pack.ConfigPackPreLoadEvent;
+import com.dfsek.terra.api.event.functional.FunctionalEventHandler;
 import com.dfsek.terra.api.injection.annotations.Inject;
 import com.dfsek.terra.api.noise.NoiseSampler;
 import com.dfsek.terra.api.registry.CheckedRegistry;
@@ -44,7 +44,7 @@ import java.util.function.Supplier;
 @Addon("config-noise-function")
 @Author("Terra")
 @Version("1.0.0")
-public class NoiseAddon extends TerraAddon implements EventListener {
+public class NoiseAddon extends TerraAddon {
     @Inject
     private TerraPlugin plugin;
 
@@ -52,10 +52,10 @@ public class NoiseAddon extends TerraAddon implements EventListener {
 
     @Override
     public void initialize() {
-        plugin.getEventManager().registerListener(this, this);
+        plugin.getEventManager()
-    }
+                .getHandler(FunctionalEventHandler.class)
-
+                .register(this, ConfigPackPreLoadEvent.class)
-    public void packPreLoad(ConfigPackPreLoadEvent event) {
+                .then(event -> {
                     CheckedRegistry<Supplier<ObjectTemplate<NoiseSampler>>> noiseRegistry = event.getPack().getOrCreateRegistry(NOISE_SAMPLER_TOKEN);
                     event.getPack()
                             .applyLoader(CellularSampler.DistanceFunction.class, (t, o, l) -> CellularSampler.DistanceFunction.valueOf((String) o))
@@ -100,5 +100,7 @@ public class NoiseAddon extends TerraAddon implements EventListener {
                     NoiseConfigPackTemplate template = new NoiseConfigPackTemplate();
                     event.loadTemplate(template);
                     packFunctions.putAll(template.getNoiseBuilderMap());
+                })
+                .failThrough();
     }
 }

common/addons/config-ore/src/main/java/com/dfsek/terra/addons/ore/OreAddon.java

@@ -5,27 +5,28 @@ import com.dfsek.terra.api.addon.TerraAddon;
 import com.dfsek.terra.api.addon.annotations.Addon;
 import com.dfsek.terra.api.addon.annotations.Author;
 import com.dfsek.terra.api.addon.annotations.Version;
-import com.dfsek.terra.api.event.EventListener;
 import com.dfsek.terra.api.event.events.config.pack.ConfigPackPreLoadEvent;
+import com.dfsek.terra.api.event.functional.FunctionalEventHandler;
 import com.dfsek.terra.api.injection.annotations.Inject;
-import com.dfsek.terra.api.registry.exception.DuplicateEntryException;
 import com.dfsek.terra.api.world.generator.GenerationStageProvider;
 
 
 @Addon("config-ore")
 @Author("Terra")
 @Version("1.0.0")
-public class OreAddon extends TerraAddon implements EventListener {
+public class OreAddon extends TerraAddon {
     @Inject
     private TerraPlugin main;
 
     @Override
     public void initialize() {
-        main.getEventManager().registerListener(this, this);
+        main.getEventManager()
-    }
+                .getHandler(FunctionalEventHandler.class)
-
+                .register(this, ConfigPackPreLoadEvent.class)
-    public void onPackLoad(ConfigPackPreLoadEvent event) throws DuplicateEntryException {
+                .then(event -> {
                     event.getPack().registerConfigType(new OreConfigType(), "ORE", 1);
                     event.getPack().getOrCreateRegistry(GenerationStageProvider.class).register("ORE", pack -> new OrePopulator(main));
+                })
+                .failThrough();
     }
 }

common/addons/config-palette/src/main/java/com/dfsek/terra/addons/palette/PaletteAddon.java

@@ -7,24 +7,26 @@ import com.dfsek.terra.api.addon.TerraAddon;
 import com.dfsek.terra.api.addon.annotations.Addon;
 import com.dfsek.terra.api.addon.annotations.Author;
 import com.dfsek.terra.api.addon.annotations.Version;
-import com.dfsek.terra.api.event.EventListener;
 import com.dfsek.terra.api.event.events.config.pack.ConfigPackPreLoadEvent;
+import com.dfsek.terra.api.event.functional.FunctionalEventHandler;
 import com.dfsek.terra.api.injection.annotations.Inject;
 
 @Addon("config-palette")
 @Author("Terra")
 @Version("1.0.0")
-public class PaletteAddon extends TerraAddon implements EventListener {
+public class PaletteAddon extends TerraAddon {
     @Inject
     private TerraPlugin main;
 
     @Override
     public void initialize() {
-        main.getEventManager().registerListener(this, this);
+        main.getEventManager()
-    }
+                .getHandler(FunctionalEventHandler.class)
-
+                .register(this, ConfigPackPreLoadEvent.class)
-    public void onPackLoad(ConfigPackPreLoadEvent event) {
+                .then(event -> {
                     event.getPack().registerConfigType(new PaletteConfigType(main), "PALETTE", 2);
                     event.getPack().applyLoader(PaletteLayerHolder.class, new PaletteLayerLoader());
+                })
+                .failThrough();
     }
 }

common/addons/config-structure/src/main/java/com/dfsek/terra/addons/structure/StructureAddon.java

@@ -5,24 +5,24 @@ import com.dfsek.terra.api.addon.TerraAddon;
 import com.dfsek.terra.api.addon.annotations.Addon;
 import com.dfsek.terra.api.addon.annotations.Author;
 import com.dfsek.terra.api.addon.annotations.Version;
-import com.dfsek.terra.api.event.EventListener;
 import com.dfsek.terra.api.event.events.config.pack.ConfigPackPreLoadEvent;
+import com.dfsek.terra.api.event.functional.FunctionalEventHandler;
 import com.dfsek.terra.api.injection.annotations.Inject;
 import com.dfsek.terra.api.structure.configured.ConfiguredStructure;
 
 @Addon("config-structure")
 @Version("1.0.0")
 @Author("Terra")
-public class StructureAddon extends TerraAddon implements EventListener {
+public class StructureAddon extends TerraAddon {
     @Inject
     private TerraPlugin main;
 
     @Override
     public void initialize() {
-        main.getEventManager().registerListener(this, this);
+        main.getEventManager()
-    }
+                .getHandler(FunctionalEventHandler.class)
-
+                .register(this, ConfigPackPreLoadEvent.class)
-    public void onConfigLoad(ConfigPackPreLoadEvent event) {
+                .then(event -> event.getPack().applyLoader(ConfiguredStructure.class, (t, o, l) -> null))
-        event.getPack().applyLoader(ConfiguredStructure.class, (t, o, l) -> null);
+                .failThrough();
     }
 }

common/addons/generation-stage-feature/src/main/java/com/dfsek/terra/addons/generation/feature/FeatureGenerationAddon.java

@@ -6,9 +6,9 @@ import com.dfsek.terra.api.addon.TerraAddon;
 import com.dfsek.terra.api.addon.annotations.Addon;
 import com.dfsek.terra.api.addon.annotations.Author;
 import com.dfsek.terra.api.addon.annotations.Version;
-import com.dfsek.terra.api.event.EventListener;
 import com.dfsek.terra.api.event.events.config.ConfigurationLoadEvent;
 import com.dfsek.terra.api.event.events.config.pack.ConfigPackPreLoadEvent;
+import com.dfsek.terra.api.event.functional.FunctionalEventHandler;
 import com.dfsek.terra.api.injection.annotations.Inject;
 import com.dfsek.terra.api.world.biome.TerraBiome;
 import com.dfsek.terra.api.world.generator.GenerationStageProvider;
@@ -16,22 +16,26 @@ import com.dfsek.terra.api.world.generator.GenerationStageProvider;
 @Addon("generation-stage-feature")
 @Version("1.0.0")
 @Author("Terra")
-public class FeatureGenerationAddon extends TerraAddon implements EventListener {
+public class FeatureGenerationAddon extends TerraAddon {
     @Inject
     private TerraPlugin main;
 
     @Override
     public void initialize() {
-        main.getEventManager().registerListener(this, this);
+        main.getEventManager()
-    }
+                .getHandler(FunctionalEventHandler.class)
+                .register(this, ConfigPackPreLoadEvent.class)
+                .then(event -> event.getPack().getOrCreateRegistry(GenerationStageProvider.class).register("FEATURE", pack -> new FeatureGenerationStage(main)))
+                .failThrough();
 
-    public void onPackLoad(ConfigPackPreLoadEvent event) {
+        main.getEventManager()
-        event.getPack().getOrCreateRegistry(GenerationStageProvider.class).register("FEATURE", pack -> new FeatureGenerationStage(main));
+                .getHandler(FunctionalEventHandler.class)
-    }
+                .register(this, ConfigurationLoadEvent.class)
-
+                .then(event -> {
-    public void onBiomeLoad(ConfigurationLoadEvent event) {
                     if(event.is(TerraBiome.class)) {
                         event.getLoadedObject(TerraBiome.class).getContext().put(event.load(new BiomeFeaturesTemplate()).get());
                     }
+                })
+                .failThrough();
     }
 }

common/addons/generation-stage-flora/src/main/java/com/dfsek/terra/addons/generation/flora/FloraGenerationAddon.java

@@ -5,9 +5,9 @@ import com.dfsek.terra.api.addon.TerraAddon;
 import com.dfsek.terra.api.addon.annotations.Addon;
 import com.dfsek.terra.api.addon.annotations.Author;
 import com.dfsek.terra.api.addon.annotations.Version;
-import com.dfsek.terra.api.event.EventListener;
 import com.dfsek.terra.api.event.events.config.ConfigurationLoadEvent;
 import com.dfsek.terra.api.event.events.config.pack.ConfigPackPreLoadEvent;
+import com.dfsek.terra.api.event.functional.FunctionalEventHandler;
 import com.dfsek.terra.api.injection.annotations.Inject;
 import com.dfsek.terra.api.world.biome.TerraBiome;
 import com.dfsek.terra.api.world.generator.GenerationStageProvider;
@@ -15,24 +15,30 @@ import com.dfsek.terra.api.world.generator.GenerationStageProvider;
 @Addon("generation-stage-flora")
 @Version("1.0.0")
 @Author("Terra")
-public class FloraGenerationAddon extends TerraAddon implements EventListener {
+public class FloraGenerationAddon extends TerraAddon {
 
     @Inject
     private TerraPlugin main;
 
     @Override
     public void initialize() {
-        main.getEventManager().registerListener(this, this);
+        main.getEventManager()
-    }
+                .getHandler(FunctionalEventHandler.class)
-
+                .register(this, ConfigPackPreLoadEvent.class)
-    public void onPackLoad(ConfigPackPreLoadEvent event) {
+                .then(event -> {
                     event.getPack().applyLoader(FloraLayer.class, FloraLayerLoader::new);
                     event.getPack().getOrCreateRegistry(GenerationStageProvider.class).register("FLORA", pack -> new FloraGenerationStage(main));
-    }
+                })
+                .failThrough();
 
-    public void onBiomeLoad(ConfigurationLoadEvent event) {
+        main.getEventManager()
+                .getHandler(FunctionalEventHandler.class)
+                .register(this, ConfigurationLoadEvent.class)
+                .then(event -> {
                     if(event.is(TerraBiome.class)) {
                         event.getLoadedObject(TerraBiome.class).getContext().put(event.load(new BiomeFloraTemplate()).get());
                     }
+                })
+                .failThrough();
     }
 }

common/addons/language-yaml/src/main/java/com/dfsek/terra/addons/yaml/YamlAddon.java

@@ -6,26 +6,26 @@ import com.dfsek.terra.api.addon.TerraAddon;
 import com.dfsek.terra.api.addon.annotations.Addon;
 import com.dfsek.terra.api.addon.annotations.Author;
 import com.dfsek.terra.api.addon.annotations.Version;
-import com.dfsek.terra.api.event.EventListener;
 import com.dfsek.terra.api.event.events.config.ConfigurationDiscoveryEvent;
+import com.dfsek.terra.api.event.functional.FunctionalEventHandler;
 import com.dfsek.terra.api.injection.annotations.Inject;
 
 @Addon("language-yaml")
 @Version("1.0.0")
 @Author("Terra")
-public class YamlAddon extends TerraAddon implements EventListener {
+public class YamlAddon extends TerraAddon {
     @Inject
     private TerraPlugin main;
 
     @Override
     public void initialize() {
-        main.getEventManager().registerListener(this, this);
+        main.getEventManager()
-    }
+                .getHandler(FunctionalEventHandler.class)
-
+                .register(this, ConfigurationDiscoveryEvent.class)
-    public void loadYamlConfigs(ConfigurationDiscoveryEvent event) {
+                .then(event -> event.getLoader().open("", ".yml").thenEntries(entries -> entries.forEach(entry -> {
-        event.getLoader().open("", ".yml").thenEntries(entries -> entries.forEach(entry -> {
                     main.getDebugLogger().info("Discovered config " + entry.getKey());
                     event.register(entry.getKey(), new YamlConfiguration(entry.getValue(), entry.getKey()));
-        }));
+                })))
+                .failThrough();
     }
 }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/TerraScriptAddon.java

@@ -1,6 +1,5 @@
 package com.dfsek.terra.addons.terrascript;
 
-import com.dfsek.tectonic.exception.ConfigException;
 import com.dfsek.tectonic.exception.LoadException;
 import com.dfsek.terra.addons.terrascript.parser.exceptions.ParseException;
 import com.dfsek.terra.addons.terrascript.script.StructureScript;
@@ -9,11 +8,10 @@ import com.dfsek.terra.api.addon.TerraAddon;
 import com.dfsek.terra.api.addon.annotations.Addon;
 import com.dfsek.terra.api.addon.annotations.Author;
 import com.dfsek.terra.api.addon.annotations.Version;
-import com.dfsek.terra.api.event.EventListener;
 import com.dfsek.terra.api.event.events.config.pack.ConfigPackPreLoadEvent;
+import com.dfsek.terra.api.event.functional.FunctionalEventHandler;
 import com.dfsek.terra.api.injection.annotations.Inject;
 import com.dfsek.terra.api.registry.CheckedRegistry;
-import com.dfsek.terra.api.registry.exception.DuplicateEntryException;
 import com.dfsek.terra.api.structure.LootTable;
 import com.dfsek.terra.api.structure.Structure;
 
@@ -23,31 +21,29 @@ import java.util.Map;
 @Addon("structure-terrascript-loader")
 @Author("Terra")
 @Version("1.0.0")
-public class TerraScriptAddon extends TerraAddon implements EventListener {
+public class TerraScriptAddon extends TerraAddon {
     @Inject
     private TerraPlugin main;
 
     @Override
     public void initialize() {
-        main.getEventManager().registerListener(this, this);
+        main.getEventManager()
-    }
+                .getHandler(FunctionalEventHandler.class)
-
+                .register(this, ConfigPackPreLoadEvent.class)
-    public void onPackLoad(ConfigPackPreLoadEvent event) throws ConfigException {
+                .then(event -> {
                     CheckedRegistry<Structure> structureRegistry = event.getPack().getOrCreateRegistry(Structure.class);
                     CheckedRegistry<LootTable> lootRegistry = event.getPack().getOrCreateRegistry(LootTable.class);
                     event.getPack().getLoader().open("", ".tesf").thenEntries(entries -> {
                         for(Map.Entry<String, InputStream> entry : entries) {
                             try {
                                 StructureScript structureScript = new StructureScript(entry.getValue(), main, structureRegistry, lootRegistry, event.getPack().getRegistryFactory().create());
-                    try {
                                 structureRegistry.register(structureScript.getId(), structureScript);
-                    } catch(DuplicateEntryException e) {
-                        throw new LoadException("Duplicate structure: ", e);
-                    }
                             } catch(ParseException e) {
                                 throw new LoadException("Failed to load script: ", e);
                             }
                         }
                     }).close();
+                })
+                .failThrough();
     }
 }

common/api/src/main/java/com/dfsek/terra/api/event/EventHandler.java

@@ -0,0 +1,7 @@
+package com.dfsek.terra.api.event;
+
+import com.dfsek.terra.api.event.events.Event;
+
+public interface EventHandler {
+    void handle(Event event);
+}

common/api/src/main/java/com/dfsek/terra/api/event/EventListener.java

@@ -1,12 +0,0 @@
-package com.dfsek.terra.api.event;
-
-import com.dfsek.terra.api.event.events.Event;
-
-/**
- * Marker interface for a class that contains event listener methods.
- *
- * @see Event
- * @see EventManager
- */
-public interface EventListener {
-}

common/api/src/main/java/com/dfsek/terra/api/event/EventManager.java

@@ -1,7 +1,8 @@
 package com.dfsek.terra.api.event;
 
-import com.dfsek.terra.api.addon.TerraAddon;
 import com.dfsek.terra.api.event.events.Event;
+import com.dfsek.terra.api.event.functional.EventContext;
+import com.dfsek.terra.api.util.reflection.TypeKey;
 
 /**
  * Manages event registration and triggering.
@@ -11,15 +12,10 @@ public interface EventManager {
      * Call an event, and return the execution status.
      *
      * @param event Event to pass to all registered EventListeners.
-     * @return False if the event is cancellable and has been cancelled, otherwise true.
      */
-    boolean callEvent(Event event);
+    void callEvent(Event event);
 
-    /**
+    <T extends EventHandler> void registerHandler(Class<T> clazz, T handler);
-     * Register an {@link EventListener} under an {@link TerraAddon}.
+
-     *
+    <T extends EventHandler> T getHandler(Class<T> clazz);
-     * @param addon    Addon to register listener for.
-     * @param listener Listener to register.
-     */
-    void registerListener(TerraAddon addon, EventListener listener);
 }

common/api/src/main/java/com/dfsek/terra/api/event/annotations/Global.java

@@ -1,17 +0,0 @@
-package com.dfsek.terra.api.event.annotations;
-
-import com.dfsek.terra.api.event.events.PackEvent;
-
-import java.lang.annotation.ElementType;
-import java.lang.annotation.Retention;
-import java.lang.annotation.RetentionPolicy;
-import java.lang.annotation.Target;
-
-/**
- * Specifies that an event handler is to handle all {@link PackEvent}s, regardless of whether the pack
- * depends on the com.dfsek.terra.addon's listener.
- */
-@Retention(RetentionPolicy.RUNTIME)
-@Target(ElementType.METHOD)
-public @interface Global {
-}

common/api/src/main/java/com/dfsek/terra/api/event/annotations/Priority.java

@@ -1,39 +0,0 @@
-package com.dfsek.terra.api.event.annotations;
-
-import java.lang.annotation.ElementType;
-import java.lang.annotation.Retention;
-import java.lang.annotation.RetentionPolicy;
-import java.lang.annotation.Target;
-
-/**
- * Annotated listener methods will have a specific priority set.
- */
-@Retention(RetentionPolicy.RUNTIME)
-@Target(ElementType.METHOD)
-public @interface Priority {
-    /**
-     * Highest possible priority. Listeners with this priority will always be invoked last.
-     */
-    int HIGHEST = Integer.MAX_VALUE;
-    /**
-     * Lowest possible priority. Listeners with this priority will always be invoked first.
-     */
-    int LOWEST = Integer.MIN_VALUE;
-    /**
-     * Default priority.
-     */
-    int NORMAL = 0;
-    /**
-     * High priority.
-     */
-    int HIGH = 1;
-    /**
-     * Low Priority.
-     */
-    int LOW = -1;
-
-    /**
-     * @return Priority of this event. Events are executed from lowest to highest priorities.
-     */
-    int value();
-}

common/api/src/main/java/com/dfsek/terra/api/event/events/FailThroughEvent.java

@@ -0,0 +1,8 @@
+package com.dfsek.terra.api.event.events;
+
+/**
+ * An event which (optionally) passes exceptions thrown by listeners to
+ * the event caller.
+ */
+public interface FailThroughEvent extends Event {
+}

common/api/src/main/java/com/dfsek/terra/api/event/events/PackEvent.java

@@ -1,13 +1,12 @@
 package com.dfsek.terra.api.event.events;
 
 import com.dfsek.terra.api.config.ConfigPack;
-import com.dfsek.terra.api.event.annotations.Global;
 
 /**
  * An event with functionality directly linked to a {@link ConfigPack}.
  * <p>
- * PackEvents are only invoked when the pack specifies the com.dfsek.terra.addon in its
+ * PackEvents are only invoked when the pack specifies the addon in its
- * {@code com.dfsek.terra.addon} key (or when the listener is annotated {@link Global}).
+ * {@code addon} key (or when the listener is global).
  */
 @SuppressWarnings("InterfaceMayBeAnnotatedFunctional")
 public interface PackEvent extends Event {

common/api/src/main/java/com/dfsek/terra/api/event/events/config/ConfigurationDiscoveryEvent.java

@@ -3,6 +3,7 @@ package com.dfsek.terra.api.event.events.config;
 import com.dfsek.tectonic.config.Configuration;
 import com.dfsek.terra.api.config.ConfigPack;
 import com.dfsek.terra.api.config.Loader;
+import com.dfsek.terra.api.event.events.FailThroughEvent;
 import com.dfsek.terra.api.event.events.PackEvent;
 
 import java.util.function.BiConsumer;
@@ -14,7 +15,7 @@ import java.util.function.Consumer;
  * Addons should listen to this event if they wish to add
  * another configuration format.
  */
-public class ConfigurationDiscoveryEvent implements PackEvent {
+public class ConfigurationDiscoveryEvent implements PackEvent, FailThroughEvent {
     private final ConfigPack pack;
     private final Loader loader;
 

common/api/src/main/java/com/dfsek/terra/api/event/events/config/ConfigurationLoadEvent.java

@@ -4,6 +4,7 @@ import com.dfsek.tectonic.abstraction.AbstractConfiguration;
 import com.dfsek.tectonic.config.ConfigTemplate;
 import com.dfsek.terra.api.config.ConfigPack;
 import com.dfsek.terra.api.config.ConfigType;
+import com.dfsek.terra.api.event.events.FailThroughEvent;
 import com.dfsek.terra.api.event.events.PackEvent;
 import com.dfsek.terra.api.util.reflection.ReflectionUtil;
 
@@ -15,7 +16,7 @@ import java.util.function.Consumer;
  * Addons should listen to this event if they wish to add
  * config values to existing {@link ConfigType}s.
  */
-public class ConfigurationLoadEvent implements PackEvent {
+public class ConfigurationLoadEvent implements PackEvent, FailThroughEvent {
     private final ConfigPack pack;
     private final AbstractConfiguration configuration;
     private final Consumer<ConfigTemplate> loader;

common/api/src/main/java/com/dfsek/terra/api/event/events/config/pack/ConfigPackLoadEvent.java

@@ -3,12 +3,13 @@ package com.dfsek.terra.api.event.events.config.pack;
 import com.dfsek.tectonic.config.ConfigTemplate;
 import com.dfsek.tectonic.exception.ConfigException;
 import com.dfsek.terra.api.config.ConfigPack;
+import com.dfsek.terra.api.event.events.FailThroughEvent;
 import com.dfsek.terra.api.event.events.PackEvent;
 
 /**
  * An event related to the loading process of config packs.
  */
-public abstract class ConfigPackLoadEvent implements PackEvent {
+public abstract class ConfigPackLoadEvent implements PackEvent, FailThroughEvent {
     private final ConfigPack pack;
     private final ExceptionalConsumer<ConfigTemplate> configLoader;
 

common/api/src/main/java/com/dfsek/terra/api/event/events/config/type/ConfigTypeLoadEvent.java

@@ -2,11 +2,12 @@ package com.dfsek.terra.api.event.events.config.type;
 
 import com.dfsek.terra.api.config.ConfigPack;
 import com.dfsek.terra.api.config.ConfigType;
+import com.dfsek.terra.api.event.events.FailThroughEvent;
 import com.dfsek.terra.api.event.events.PackEvent;
 import com.dfsek.terra.api.registry.CheckedRegistry;
 import com.dfsek.terra.api.util.reflection.ReflectionUtil;
 
-public abstract class ConfigTypeLoadEvent implements PackEvent {
+public abstract class ConfigTypeLoadEvent implements PackEvent, FailThroughEvent {
     private final ConfigType<?, ?> type;
     private final CheckedRegistry<?> registry;
 

common/api/src/main/java/com/dfsek/terra/api/event/events/config/type/ConfigTypePostLoadEvent.java

@@ -4,7 +4,7 @@ import com.dfsek.terra.api.config.ConfigPack;
 import com.dfsek.terra.api.config.ConfigType;
 import com.dfsek.terra.api.registry.CheckedRegistry;
 
-public class ConfigTypePostLoadEvent extends ConfigTypeLoadEvent{
+public class ConfigTypePostLoadEvent extends ConfigTypeLoadEvent {
     public ConfigTypePostLoadEvent(ConfigType<?, ?> type, CheckedRegistry<?> registry, ConfigPack pack) {
         super(type, registry, pack);
     }

common/api/src/main/java/com/dfsek/terra/api/event/events/config/type/ConfigTypePreLoadEvent.java

@@ -4,7 +4,7 @@ import com.dfsek.terra.api.config.ConfigPack;
 import com.dfsek.terra.api.config.ConfigType;
 import com.dfsek.terra.api.registry.CheckedRegistry;
 
-public class ConfigTypePreLoadEvent extends ConfigTypeLoadEvent{
+public class ConfigTypePreLoadEvent extends ConfigTypeLoadEvent {
     public ConfigTypePreLoadEvent(ConfigType<?, ?> type, CheckedRegistry<?> registry, ConfigPack pack) {
         super(type, registry, pack);
     }

common/api/src/main/java/com/dfsek/terra/api/event/functional/EventContext.java

@@ -0,0 +1,16 @@
+package com.dfsek.terra.api.event.functional;
+
+import com.dfsek.terra.api.event.EventManager;
+import com.dfsek.terra.api.event.events.Event;
+
+import java.util.function.Consumer;
+
+public interface EventContext<T extends Event> {
+    EventContext<T> then(Consumer<T> action);
+
+    EventContext<T> priority(int priority);
+
+    EventContext<T> failThrough();
+
+    EventContext<T> global();
+}

common/api/src/main/java/com/dfsek/terra/api/event/functional/FunctionalEventHandler.java

@@ -0,0 +1,12 @@
+package com.dfsek.terra.api.event.functional;
+
+import com.dfsek.terra.api.addon.TerraAddon;
+import com.dfsek.terra.api.event.EventHandler;
+import com.dfsek.terra.api.event.events.Event;
+import com.dfsek.terra.api.util.reflection.TypeKey;
+
+public interface FunctionalEventHandler extends EventHandler {
+    <T extends Event> EventContext<T> register(TerraAddon addon, Class<T> clazz);
+
+    <T extends Event> EventContext<T> register(TerraAddon addon, TypeKey<T> clazz);
+}

common/implementation/src/main/java/com/dfsek/terra/event/EventContextImpl.java

@@ -0,0 +1,85 @@
+package com.dfsek.terra.event;
+
+import com.dfsek.terra.api.addon.TerraAddon;
+import com.dfsek.terra.api.event.events.Event;
+import com.dfsek.terra.api.event.events.FailThroughEvent;
+import com.dfsek.terra.api.event.functional.EventContext;
+import com.dfsek.terra.api.util.reflection.ReflectionUtil;
+import org.jetbrains.annotations.NotNull;
+
+import java.lang.reflect.Type;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.function.Consumer;
+
+public class EventContextImpl<T extends Event> implements EventContext<T>, Comparable<EventContextImpl<?>> {
+    private final List<Consumer<T>> actions = new ArrayList<>();
+    private int priority;
+    private boolean failThrough = false;
+    private boolean global = false;
+
+    private final TerraAddon addon;
+
+    private final Type eventType;
+
+    private final FunctionalEventHandlerImpl parent;
+
+    public EventContextImpl(TerraAddon addon, Type eventType, FunctionalEventHandlerImpl parent) {
+        this.addon = addon;
+        this.eventType = eventType;
+        this.parent = parent;
+    }
+
+    public void handle(T event) {
+        actions.forEach(action -> action.accept(event));
+    }
+
+    @Override
+    public EventContext<T> then(Consumer<T> action) {
+        actions.add(action);
+        return this;
+    }
+
+    @Override
+    public EventContext<T> priority(int priority) {
+        this.priority = priority;
+        parent.recomputePriorities(eventType);
+        return this;
+    }
+
+    @Override
+    public EventContext<T> failThrough() {
+        if(!FailThroughEvent.class.isAssignableFrom(ReflectionUtil.getRawType(eventType))) {
+            throw new IllegalStateException("Cannot fail-through on event which does not implement FailThroughEvent: " + ReflectionUtil.typeToString(eventType));
+        }
+        this.failThrough = true;
+        return this;
+    }
+
+    @Override
+    public EventContext<T> global() {
+        this.global = true;
+        return this;
+    }
+
+    @Override
+    public int compareTo(@NotNull EventContextImpl<?> o) {
+        return this.priority - o.priority;
+    }
+
+    public boolean isGlobal() {
+        return global;
+    }
+
+    public int getPriority() {
+        return priority;
+    }
+
+    public TerraAddon getAddon() {
+        return addon;
+    }
+
+    public boolean isFailThrough() {
+        return failThrough;
+    }
+}

common/implementation/src/main/java/com/dfsek/terra/event/EventManagerImpl.java

@@ -1,111 +1,38 @@
 package com.dfsek.terra.event;
 
 import com.dfsek.terra.api.TerraPlugin;
-import com.dfsek.terra.api.addon.TerraAddon;
+import com.dfsek.terra.api.event.EventHandler;
-import com.dfsek.terra.api.event.EventListener;
 import com.dfsek.terra.api.event.EventManager;
-import com.dfsek.terra.api.event.annotations.Global;
-import com.dfsek.terra.api.event.annotations.Priority;
-import com.dfsek.terra.api.event.events.Cancellable;
 import com.dfsek.terra.api.event.events.Event;
-import com.dfsek.terra.api.event.events.PackEvent;
+import com.dfsek.terra.api.event.functional.FunctionalEventHandler;
-import com.dfsek.terra.api.util.reflection.ReflectionUtil;
 
-import java.io.PrintWriter;
-import java.io.StringWriter;
-import java.lang.reflect.InvocationTargetException;
-import java.lang.reflect.Method;
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.Comparator;
 import java.util.HashMap;
-import java.util.List;
 import java.util.Map;
 
 public class EventManagerImpl implements EventManager {
-    private final Map<Class<? extends Event>, List<ListenerHolder>> listeners = new HashMap<>();
+    private final Map<Class<?>, EventHandler> handlers = new HashMap<>();
     private final TerraPlugin main;
 
     public EventManagerImpl(TerraPlugin main) {
         this.main = main;
+        registerHandler(FunctionalEventHandler.class, new FunctionalEventHandlerImpl(main)); // default handler
     }
 
     @Override
-    public boolean callEvent(Event event) {
+    public void callEvent(Event event) {
-        listeners.getOrDefault(event.getClass(), Collections.emptyList()).forEach(listenerHolder -> {
+        handlers.values().forEach(handler -> handler.handle(event));
-                    try {
-                        if(event instanceof PackEvent && !listenerHolder.global) {
-                            PackEvent packEvent = (PackEvent) event;
-                            if(packEvent
-                                    .getPack()
-                                    .addons()
-                                    .contains(listenerHolder.addon)) {
-                                listenerHolder.method.invoke(listenerHolder.listener, event);
     }
-                        } else {
+
-                            listenerHolder.method.invoke(listenerHolder.listener, event);
+    @Override
-                        }
+    public <T extends EventHandler> void registerHandler(Class<T> clazz, T handler) {
-                    } catch(InvocationTargetException e) {
+        handlers.put(clazz, handler);
-                        StringWriter writer = new StringWriter();
-                        e.getTargetException().printStackTrace(new PrintWriter(writer));
-                        main.logger().warning("Exception occurred during event handling:");
-                        main.logger().warning(writer.toString());
-                        main.logger().warning("Report this to the maintainers of " + listenerHolder.method.getName());
-                    } catch(Exception e) {
-                        StringWriter writer = new StringWriter();
-                        e.printStackTrace(new PrintWriter(writer));
-                        main.logger().warning("Exception occurred during event handling:");
-                        main.logger().warning(writer.toString());
-                        main.logger().warning("Report this to the maintainers of " + listenerHolder.method.getName());
-                    }
-                }
-        );
-        if(event instanceof Cancellable) return !((Cancellable) event).isCancelled();
-        return true;
     }
 
     @SuppressWarnings("unchecked")
     @Override
-    public void registerListener(TerraAddon addon, EventListener listener) {
+    public <T extends EventHandler> T getHandler(Class<T> clazz) {
-        Class<? extends EventListener> listenerClass = listener.getClass();
+        return (T) handlers.computeIfAbsent(clazz, c -> {
-        Method[] methods = ReflectionUtil.getMethods(listenerClass);
+            throw new IllegalArgumentException("No event handler registered for class " + clazz.getCanonicalName());
-
+        });
-        for(Method method : methods) {
-            if(method.getParameterCount() != 1) continue; // Check that parameter count is only 1.
-            Class<?> eventParam = method.getParameterTypes()[0];
-            if(!Event.class.isAssignableFrom(eventParam)) continue; // Check that parameter is an Event.
-
-            Priority p = method.getAnnotation(Priority.class);
-
-            int priority = p == null ? 0 : p.value();
-
-            method.setAccessible(true);
-
-            List<ListenerHolder> holders = listeners.computeIfAbsent((Class<? extends Event>) eventParam, e -> new ArrayList<>());
-
-            holders.add(new ListenerHolder(method, listener, priority, addon, method.getAnnotation(Global.class) != null));
-
-            holders.sort(Comparator.comparingInt(ListenerHolder::getPriority)); // Sort priorities.
-        }
-    }
-
-    private static final class ListenerHolder {
-        private final Method method;
-        private final EventListener listener;
-        private final int priority;
-        private final TerraAddon addon;
-        private final boolean global;
-
-        private ListenerHolder(Method method, EventListener listener, int priority, TerraAddon addon, boolean global) {
-            this.method = method;
-            this.listener = listener;
-            this.priority = priority;
-            this.addon = addon;
-            this.global = global;
-        }
-
-        public int getPriority() {
-            return priority;
-        }
     }
 }

common/implementation/src/main/java/com/dfsek/terra/event/FunctionalEventHandlerImpl.java

@@ -0,0 +1,71 @@
+package com.dfsek.terra.event;
+
+import com.dfsek.terra.api.TerraPlugin;
+import com.dfsek.terra.api.addon.TerraAddon;
+import com.dfsek.terra.api.event.events.Event;
+import com.dfsek.terra.api.event.events.FailThroughEvent;
+import com.dfsek.terra.api.event.events.PackEvent;
+import com.dfsek.terra.api.event.functional.EventContext;
+import com.dfsek.terra.api.event.functional.FunctionalEventHandler;
+import com.dfsek.terra.api.util.reflection.TypeKey;
+
+import java.io.PrintWriter;
+import java.io.StringWriter;
+import java.lang.reflect.Type;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+public class FunctionalEventHandlerImpl implements FunctionalEventHandler {
+    private final Map<Type, List<EventContextImpl<?>>> contextMap = new HashMap<>();
+
+    private final TerraPlugin main;
+
+    public FunctionalEventHandlerImpl(TerraPlugin main) {
+        this.main = main;
+    }
+
+    @SuppressWarnings("unchecked")
+    @Override
+    public void handle(Event event) {
+        contextMap.getOrDefault(event.getClass(), Collections.emptyList()).forEach(context -> {
+            try {
+                if(event instanceof PackEvent) {
+                    if((context.isGlobal() || ((PackEvent) event).getPack().addons().contains(context.getAddon()))) {
+                        ((EventContextImpl<Event>) context).handle(event);
+                    }
+                } else {
+                    ((EventContextImpl<Event>) context).handle(event);
+                }
+            } catch(Exception e) {
+                if(context.isFailThrough() && event instanceof FailThroughEvent) throw e; // Rethrow if it's fail-through.
+                StringWriter writer = new StringWriter();
+                e.printStackTrace(new PrintWriter(writer));
+                main.logger().warning("Exception occurred during event handling:");
+                main.logger().warning(writer.toString());
+                main.logger().warning("Report this to the maintainers of " + context.getAddon().getName() + ", " + context.getAddon().getAuthor());
+            }
+        });
+    }
+
+    @Override
+    public <T extends Event> EventContext<T> register(TerraAddon addon, Class<T> clazz) {
+        EventContextImpl<T> eventContext = new EventContextImpl<>(addon, clazz, this);
+        contextMap.computeIfAbsent(clazz, c -> new ArrayList<>()).add(eventContext);
+        return eventContext;
+    }
+
+    @Override
+    public <T extends Event> EventContext<T> register(TerraAddon addon, TypeKey<T> clazz) {
+        EventContextImpl<T> eventContext = new EventContextImpl<>(addon, clazz.getType(), this);
+        contextMap.computeIfAbsent(clazz.getType(), c -> new ArrayList<>()).add(eventContext);
+        return eventContext;
+    }
+
+    public void recomputePriorities(Type target) {
+        contextMap.get(target).sort(Comparator.naturalOrder());
+    }
+}

platforms/bukkit/src/main/java/com/dfsek/terra/bukkit/TerraBukkitPlugin.java

@@ -33,7 +33,6 @@ import com.dfsek.terra.bukkit.handles.BukkitWorldHandle;
 import com.dfsek.terra.bukkit.listeners.CommonListener;
 import com.dfsek.terra.bukkit.listeners.PaperListener;
 import com.dfsek.terra.bukkit.listeners.SpigotListener;
-import com.dfsek.terra.bukkit.listeners.TerraListener;
 import com.dfsek.terra.bukkit.util.PaperUtil;
 import com.dfsek.terra.bukkit.world.BukkitBiome;
 import com.dfsek.terra.bukkit.world.BukkitWorld;
@@ -343,7 +342,7 @@ public class TerraBukkitPlugin extends JavaPlugin implements TerraPlugin {
 
         @Override
         public void initialize() {
-            main.getEventManager().registerListener(this, new TerraListener(main));
+
         }
     }
 }

platforms/bukkit/src/main/java/com/dfsek/terra/bukkit/listeners/TerraListener.java

@@ -1,33 +0,0 @@
-package com.dfsek.terra.bukkit.listeners;
-
-import com.dfsek.terra.api.TerraPlugin;
-import com.dfsek.terra.api.event.EventListener;
-import com.dfsek.terra.api.event.annotations.Global;
-import com.dfsek.terra.api.event.annotations.Priority;
-import com.dfsek.terra.api.event.events.config.pack.ConfigPackPreLoadEvent;
-import com.dfsek.terra.api.registry.exception.DuplicateEntryException;
-import com.dfsek.terra.api.world.Tree;
-import com.dfsek.terra.bukkit.world.BukkitAdapter;
-import com.dfsek.terra.bukkit.world.BukkitTree;
-import org.bukkit.TreeType;
-
-public class TerraListener implements EventListener {
-    private final TerraPlugin main;
-
-    public TerraListener(TerraPlugin main) {
-        this.main = main;
-    }
-
-    @Global
-    @Priority(Priority.LOWEST)
-    public void injectTrees(ConfigPackPreLoadEvent event) {
-        for(TreeType value : TreeType.values()) {
-            try {
-                String id = BukkitAdapter.TREE_TRANSFORMER.translate(value);
-                event.getPack().getCheckedRegistry(Tree.class).register(id, new BukkitTree(value, main));
-                event.getPack().getCheckedRegistry(Tree.class).get(id); // Platform trees should never be marked "dead"
-            } catch(DuplicateEntryException ignore) { // If another com.dfsek.terra.addon has already registered trees, do nothing.
-            }
-        }
-    }
-}

platforms/fabric/src/main/java/com/dfsek/terra/fabric/TerraFabricPlugin.java

@@ -14,13 +14,10 @@ import com.dfsek.terra.api.command.CommandManager;
 import com.dfsek.terra.api.command.exception.MalformedCommandException;
 import com.dfsek.terra.api.config.ConfigPack;
 import com.dfsek.terra.api.config.PluginConfig;
-import com.dfsek.terra.api.event.EventListener;
 import com.dfsek.terra.api.event.EventManager;
-import com.dfsek.terra.api.event.annotations.Global;
-import com.dfsek.terra.api.event.annotations.Priority;
 import com.dfsek.terra.api.event.events.config.pack.ConfigPackPostLoadEvent;
 import com.dfsek.terra.api.event.events.config.pack.ConfigPackPreLoadEvent;
-import com.dfsek.terra.api.event.events.config.type.ConfigTypePostLoadEvent;
+import com.dfsek.terra.api.event.functional.FunctionalEventHandler;
 import com.dfsek.terra.api.handle.ItemHandle;
 import com.dfsek.terra.api.handle.WorldHandle;
 import com.dfsek.terra.api.lang.Language;
@@ -69,7 +66,6 @@ import net.minecraft.world.dimension.DimensionType;
 import net.minecraft.world.gen.decorator.Decorator;
 import net.minecraft.world.gen.decorator.NopeDecoratorConfig;
 import net.minecraft.world.gen.feature.ConfiguredFeature;
-import net.minecraft.world.gen.feature.ConfiguredFeatures;
 import net.minecraft.world.gen.feature.DefaultFeatureConfig;
 import net.minecraft.world.gen.feature.FeatureConfig;
 import org.apache.commons.io.FileUtils;
@@ -288,16 +284,15 @@ public class TerraFabricPlugin implements TerraPlugin, ModInitializer {
     @Addon("Terra-Fabric")
     @Author("Terra")
     @Version("1.0.0")
-    public final class FabricAddon extends TerraAddon implements EventListener {
+    public final class FabricAddon extends TerraAddon {
         private final Map<ConfigPack, Pair<PreLoadCompatibilityOptions, PostLoadCompatibilityOptions>> templates = new HashMap<>();
 
         @Override
         public void initialize() {
-            eventManager.registerListener(this, this);
+            eventManager
-        }
+                    .getHandler(FunctionalEventHandler.class)
-
+                    .register(this, ConfigPackPreLoadEvent.class)
-        @Global
+                    .then(event -> {
-        public void onPackLoad(ConfigPackPreLoadEvent event) {
                         PreLoadCompatibilityOptions template = new PreLoadCompatibilityOptions();
                         try {
                             event.loadTemplate(template);
@@ -317,12 +312,13 @@ public class TerraFabricPlugin implements TerraPlugin, ModInitializer {
                             });
                         }
                         templates.put(event.getPack(), Pair.of(template, null));
+                    })
+                    .global();
 
-        }
+            eventManager
-
+                    .getHandler(FunctionalEventHandler.class)
-        @Priority(Priority.HIGHEST)
+                    .register(this, ConfigPackPostLoadEvent.class)
-        @Global
+                    .then(event -> {
-        public void createInjectionOptions(ConfigPackPostLoadEvent event) {
                         PostLoadCompatibilityOptions template = new PostLoadCompatibilityOptions();
 
                         try {
@@ -332,24 +328,34 @@ public class TerraFabricPlugin implements TerraPlugin, ModInitializer {
                         }
 
                         templates.get(event.getPack()).setRight(template);
-        }
+                    })
+                    .priority(100)
+                    .global();
 
-        @Global
+            eventManager
-        public void injectBiomes(BiomeRegistrationEvent event) {
+                    .getHandler(FunctionalEventHandler.class)
+                    .register(this, BiomeRegistrationEvent.class)
+                    .then(event -> {
                         logger.info("Registering biomes...");
                         Registry<Biome> biomeRegistry = event.getRegistryManager().get(Registry.BIOME_KEY);
                         configRegistry.forEach(pack -> pack.getCheckedRegistry(TerraBiome.class).forEach((id, biome) -> FabricUtil.registerOrOverwrite(biomeRegistry, Registry.BIOME_KEY, new Identifier("terra", FabricUtil.createBiomeID(pack, id)), FabricUtil.createBiome(biome, pack, event.getRegistryManager())))); // Register all Terra biomes.
                         logger.info("Biomes registered.");
-        }
+                    })
+                    .global();
 
-        @Global
+            eventManager
-        public void initializePacks(GameInitializationEvent event) {
+                    .getHandler(FunctionalEventHandler.class)
+                    .register(this, GameInitializationEvent.class)
+                    .then(event -> {
                         TerraFabricPlugin main = TerraFabricPlugin.getInstance();
                         main.logger().info("Loading config packs...");
                         configRegistry.loadAll(TerraFabricPlugin.this);
                         logger.info("Loaded packs.");
+                    })
+                    .global();
         }
 
+
         private void injectTree(CheckedRegistry<Tree> registry, String id, ConfiguredFeature<?, ?> tree) {
             try {
                 registry.register(id, (Tree) tree);