From bf4818cf97da432c3e5b0b2a54bab9975bb08e50 Mon Sep 17 00:00:00 2001
From: yueh <yueh@users.noreply.github.com>
Date: Sun, 27 May 2018 21:15:35 +0200
Subject: [PATCH] Updated Cell Registry safety and docs (#3383)

The Cell registry now ensures that the first handler is our own as other
addons might depend on it.
Updated docs to match the new requirements.
Made internal handler classes final.
---
 .../java/appeng/api/storage/ICellRegistry.java   | 11 ++++++++++-
 .../registries/cell/BasicCellHandler.java        |  2 +-
 .../features/registries/cell/CellRegistry.java   | 16 +++++++++++-----
 .../registries/cell/CreativeCellHandler.java     |  2 +-
 4 files changed, 23 insertions(+), 8 deletions(-)

diff --git a/src/api/java/appeng/api/storage/ICellRegistry.java b/src/api/java/appeng/api/storage/ICellRegistry.java
index a692e0044..ad3563bc0 100644
--- a/src/api/java/appeng/api/storage/ICellRegistry.java
+++ b/src/api/java/appeng/api/storage/ICellRegistry.java
@@ -24,7 +24,11 @@
 package appeng.api.storage;
 
 
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
+
 import net.minecraft.item.ItemStack;
+import net.minecraftforge.fml.common.event.FMLInitializationEvent;
 
 import appeng.api.IAppEngApi;
 import appeng.api.storage.data.IAEStack;
@@ -42,9 +46,12 @@ public interface ICellRegistry
 	/**
 	 * Register a new handler.
 	 *
+	 * Never be call before {@link FMLInitializationEvent} was handled by AE2.
+	 * Will throw an exception otherwise.
+	 *
 	 * @param handler cell handler
 	 */
-	void addCellHandler( ICellHandler handler );
+	void addCellHandler( @Nonnull ICellHandler handler );
 
 	/**
 	 * return true, if you can get a InventoryHandler for the item passed.
@@ -63,6 +70,7 @@ public interface ICellRegistry
 	 *
 	 * @return the handler registered for this item type.
 	 */
+	@Nullable
 	ICellHandler getHandler( ItemStack is );
 
 	/**
@@ -74,5 +82,6 @@ public interface ICellRegistry
 	 *
 	 * @return new IMEInventoryHandler, or null if there isn't one.
 	 */
+	@Nullable
 	<T extends IAEStack<T>> IMEInventoryHandler<T> getCellInventory( ItemStack is, ISaveProvider host, IStorageChannel<T> chan );
 }
\ No newline at end of file
diff --git a/src/main/java/appeng/core/features/registries/cell/BasicCellHandler.java b/src/main/java/appeng/core/features/registries/cell/BasicCellHandler.java
index e386cdd26..063ba963c 100644
--- a/src/main/java/appeng/core/features/registries/cell/BasicCellHandler.java
+++ b/src/main/java/appeng/core/features/registries/cell/BasicCellHandler.java
@@ -41,7 +41,7 @@ import appeng.me.storage.CellInventoryHandler;
 import appeng.util.Platform;
 
 
-public class BasicCellHandler implements ICellHandler
+public final class BasicCellHandler implements ICellHandler
 {
 
 	@Override
diff --git a/src/main/java/appeng/core/features/registries/cell/CellRegistry.java b/src/main/java/appeng/core/features/registries/cell/CellRegistry.java
index dd1726fed..0bd4f0c1f 100644
--- a/src/main/java/appeng/core/features/registries/cell/CellRegistry.java
+++ b/src/main/java/appeng/core/features/registries/cell/CellRegistry.java
@@ -22,6 +22,9 @@ package appeng.core.features.registries.cell;
 import java.util.ArrayList;
 import java.util.List;
 
+import com.google.common.base.Preconditions;
+import com.google.common.base.Verify;
+
 import net.minecraft.item.ItemStack;
 
 import appeng.api.storage.ICellHandler;
@@ -43,12 +46,15 @@ public class CellRegistry implements ICellRegistry
 	}
 
 	@Override
-	public void addCellHandler( final ICellHandler h )
+	public void addCellHandler( final ICellHandler handler )
 	{
-		if( h != null )
-		{
-			this.handlers.add( h );
-		}
+		Preconditions.checkNotNull( handler, "Called before FMLInitializationEvent." );
+		Preconditions.checkArgument( !this.handlers.contains( handler ), "Tried to register the same handler instance twice." );
+
+		this.handlers.add( handler );
+
+		// Verify that the first entry is always our own handler.
+		Verify.verify( this.handlers.get( 0 ) instanceof BasicCellHandler );
 	}
 
 	@Override
diff --git a/src/main/java/appeng/core/features/registries/cell/CreativeCellHandler.java b/src/main/java/appeng/core/features/registries/cell/CreativeCellHandler.java
index 414950086..8c4b4168b 100644
--- a/src/main/java/appeng/core/features/registries/cell/CreativeCellHandler.java
+++ b/src/main/java/appeng/core/features/registries/cell/CreativeCellHandler.java
@@ -38,7 +38,7 @@ import appeng.me.storage.CreativeCellInventory;
 import appeng.util.Platform;
 
 
-public class CreativeCellHandler implements ICellHandler
+public final class CreativeCellHandler implements ICellHandler
 {
 
 	@Override