SPIGOT-7011, SPIGOT-7065: Overhaul of structures

By: DerFrZocker <derrieple@gmail.com>

paper-server/src/main/java/org/bukkit/craftbukkit/CraftRegistry.java

@@ -0,0 +1,74 @@
+package org.bukkit.craftbukkit;
+
+import java.util.HashMap;
+import java.util.Iterator;
+import java.util.Map;
+import java.util.function.BiFunction;
+import java.util.stream.Stream;
+import net.minecraft.core.IRegistry;
+import net.minecraft.core.IRegistryCustom;
+import org.bukkit.Keyed;
+import org.bukkit.NamespacedKey;
+import org.bukkit.Registry;
+import org.bukkit.craftbukkit.generator.strucutre.CraftStructure;
+import org.bukkit.craftbukkit.generator.strucutre.CraftStructureType;
+import org.bukkit.craftbukkit.util.CraftNamespacedKey;
+import org.bukkit.generator.structure.Structure;
+import org.bukkit.generator.structure.StructureType;
+
+public class CraftRegistry<B extends Keyed, M> implements Registry<B> {
+
+    public static <B extends Keyed> Registry<?> createRegistry(Class<B> bukkitClass, IRegistryCustom registryHolder) {
+        if (bukkitClass == Structure.class) {
+            return new CraftRegistry<>(registryHolder.registryOrThrow(IRegistry.STRUCTURE_REGISTRY), CraftStructure::new);
+        }
+        if (bukkitClass == StructureType.class) {
+            return new CraftRegistry<>(IRegistry.STRUCTURE_TYPES, CraftStructureType::new);
+        }
+
+        return null;
+    }
+
+    private final Map<NamespacedKey, B> cache = new HashMap<>();
+    private final IRegistry<M> minecraftRegistry;
+    private final BiFunction<NamespacedKey, M, B> minecraftToBukkit;
+
+    public CraftRegistry(IRegistry<M> minecraftRegistry, BiFunction<NamespacedKey, M, B> minecraftToBukkit) {
+        this.minecraftRegistry = minecraftRegistry;
+        this.minecraftToBukkit = minecraftToBukkit;
+    }
+
+    @Override
+    public B get(NamespacedKey namespacedKey) {
+        B cached = cache.get(namespacedKey);
+        if (cached != null) {
+            return cached;
+        }
+
+        B bukkit = createBukkit(namespacedKey, minecraftRegistry.getOptional(CraftNamespacedKey.toMinecraft(namespacedKey)).orElse(null));
+        if (bukkit == null) {
+            return null;
+        }
+
+        cache.put(namespacedKey, bukkit);
+
+        return bukkit;
+    }
+
+    @Override
+    public Iterator<B> iterator() {
+        return values().iterator();
+    }
+
+    public B createBukkit(NamespacedKey namespacedKey, M minecraft) {
+        if (minecraft == null) {
+            return null;
+        }
+
+        return minecraftToBukkit.apply(namespacedKey, minecraft);
+    }
+
+    public Stream<B> values() {
+        return minecraftRegistry.keySet().stream().map(minecraftKey -> get(CraftNamespacedKey.fromMinecraft(minecraftKey)));
+    }
+}