Rework AEItemStack (#3091)

* Use itemstack as itemdef
* HIGH_TAG/LOW_TAG should be compared both directions
* Remove getTagCompound
* Make Itemlist implementation independent
* Cache item id for performance reasons
* Add preconditions to saveguard against external meddling
* Chache itemDamage
* Remove IAEStackSearchKey for now, rename getDisplayStack

src/main/java/appeng/util/item/AEItemStackRegistry.java

@@ -0,0 +1,71 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2017 AlgorithmX2
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to
+ * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+ * the Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+ * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+package appeng.util.item;
+
+
+import java.lang.ref.WeakReference;
+import java.util.WeakHashMap;
+
+import javax.annotation.Nonnull;
+
+import net.minecraft.item.ItemStack;
+
+
+public final class AEItemStackRegistry
+{
+	private static final WeakHashMap<AESharedItemStack, WeakReference<AESharedItemStack>> REGISTRY = new WeakHashMap<>();
+
+	private AEItemStackRegistry()
+	{
+	}
+
+	static synchronized AESharedItemStack getRegisteredStack( final @Nonnull ItemStack itemStack )
+	{
+		if( itemStack.isEmpty() )
+		{
+			throw new IllegalArgumentException( "stack cannot be empty" );
+		}
+
+		int oldStackSize = itemStack.getCount();
+		itemStack.setCount( 1 );
+
+		AESharedItemStack search = new AESharedItemStack( itemStack );
+		WeakReference<AESharedItemStack> weak = REGISTRY.get( search );
+		AESharedItemStack ret = null;
+
+		if( weak != null )
+		{
+			ret = weak.get();
+		}
+
+		if( ret == null )
+		{
+			ret = new AESharedItemStack( itemStack.copy() );
+			REGISTRY.put( ret, new WeakReference<>( ret ) );
+		}
+		itemStack.setCount( oldStackSize );
+
+		return ret;
+	}
+}