Add getCodec method in ForgeRegistry (#8333)

src/main/java/net/minecraftforge/registries/ForgeRegistry.java

@@ -1,6 +1,6 @@
 /*
  * Minecraft Forge
- * Copyright (c) 2016-2021.
+ * Copyright (c) 2016-2022.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
@@ -25,6 +25,10 @@ import java.util.Map.Entry;
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 
+import com.mojang.datafixers.util.Pair;
+import com.mojang.serialization.Codec;
+import com.mojang.serialization.DataResult;
+import com.mojang.serialization.DynamicOps;
 import net.minecraftforge.common.util.LogMessageAdapter;
 import net.minecraftforge.fml.ModLoadingContext;
 import net.minecraftforge.fml.util.ObfuscationReflectionHelper;
@@ -96,6 +100,8 @@ public class ForgeRegistry<V extends IForgeRegistryEntry<V>> implements IForgeRe
     private final ResourceKey<Registry<V>> key;
     private final RegistryBuilder<V> builder;
 
+    private final Codec<V> codec = new RegistryCodec();
+
     ForgeRegistry(RegistryManager stage, ResourceLocation name, RegistryBuilder<V> builder)
     {
         this.name = name;
@@ -180,6 +186,12 @@ public class ForgeRegistry<V extends IForgeRegistryEntry<V>> implements IForgeRe
         return tagFolder;
     }
 
+    @Override
+    public Codec<V> getCodec()
+    {
+        return this.codec;
+    }
+
     @Override
     public void registerAll(@SuppressWarnings("unchecked") V... values)
     {
@@ -871,6 +883,45 @@ public class ForgeRegistry<V extends IForgeRegistryEntry<V>> implements IForgeRe
         return ret;
     }
 
+    private class RegistryCodec implements Codec<V>
+    {
+        @Override
+        public <T> DataResult<Pair<V, T>> decode(DynamicOps<T> ops, T input)
+        {
+            if (ops.compressMaps())
+            {
+                return ops.getNumberValue(input).flatMap(n ->
+                {
+                    int id = n.intValue();
+                    if (ids.get(id) == null)
+                    {
+                        return DataResult.error("Unknown registry id in " + ForgeRegistry.this.key + ": " + n);
+                    }
+                    V val = ForgeRegistry.this.getValue(id);
+                    return DataResult.success(val);
+                }).map(v -> Pair.of(v, ops.empty()));
+            }
+            else
+            {
+                return ResourceLocation.CODEC.decode(ops, input).flatMap(keyValuePair -> !ForgeRegistry.this.containsKey(keyValuePair.getFirst())
+                        ? DataResult.error("Unknown registry key in " + ForgeRegistry.this.key + ": " + keyValuePair.getFirst())
+                        : DataResult.success(keyValuePair.mapFirst(ForgeRegistry.this::getValue)));
+            }
+        }
+
+        @Override
+        public <T> DataResult<T> encode(V input, DynamicOps<T> ops, T prefix)
+        {
+            ResourceLocation key = getKey(input);
+            if (key == null)
+            {
+                return DataResult.error("Unknown registry element in " + ForgeRegistry.this.key + ": " + input);
+            }
+            T toMerge = ops.compressMaps() ? ops.createInt(getID(input)) : ops.createString(key.toString());
+            return ops.mergeToPrimitive(prefix, toMerge);
+        }
+    }
+
     public static class Snapshot
     {
         private static final Comparator<ResourceLocation> sorter = (a,b) -> a.compareNamespaced(b);

src/main/java/net/minecraftforge/registries/IForgeRegistry.java

@@ -1,6 +1,6 @@
 /*
  * Minecraft Forge
- * Copyright (c) 2016-2021.
+ * Copyright (c) 2016-2022.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
@@ -26,6 +26,7 @@ import java.util.Set;
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 
+import com.mojang.serialization.Codec;
 import net.minecraft.resources.ResourceKey;
 import net.minecraft.resources.ResourceLocation;
 
@@ -56,6 +57,8 @@ public interface IForgeRegistry<V extends IForgeRegistryEntry<V>> extends Iterab
     @Nonnull Collection<V>                 getValues();
     @Nonnull Set<Entry<ResourceKey<V>, V>> getEntries();
 
+    @Nonnull Codec<V> getCodec();
+
     /**
      * Retrieve the slave map of type T from the registry.
      * Slave maps are maps which are dependent on registry content in some way.