Added some more utility methods for database component to allow manipulating slots (copy and clear).

src/main/scala/li/cil/oc/server/component/UpgradeDatabase.scala

@@ -1,9 +1,14 @@
 package li.cil.oc.server.component
 
 import com.google.common.hash.Hashing
-import li.cil.oc.api.machine.{Arguments, Callback, Context}
+import li.cil.oc.api.Network
-import li.cil.oc.api.network.{Component, Visibility}
+import li.cil.oc.api.internal
-import li.cil.oc.api.{Network, internal, prefab}
+import li.cil.oc.api.machine.Arguments
+import li.cil.oc.api.machine.Callback
+import li.cil.oc.api.machine.Context
+import li.cil.oc.api.network.Component
+import li.cil.oc.api.network.Visibility
+import li.cil.oc.api.prefab
 import li.cil.oc.util.ExtendedArguments._
 import li.cil.oc.util.ExtendedNBT._
 import net.minecraft.inventory.IInventory
@@ -37,21 +42,38 @@ class UpgradeDatabase(val data: IInventory) extends prefab.ManagedEnvironment wi
   @Callback(doc = "function(hash:string):number -- Get the index of an item stack with the specified hash. Returns a negative value if no such stack was found.")
   def indexOf(context: Context, args: Arguments): Array[AnyRef] = result(indexOf(args.checkString(0), 1))
 
+  @Callback(doc = "function(slot:number):boolean -- Clears the specified slot. Returns true if there was something in the slot before.")
+  def clearSlot(context: Context, args: Arguments): Array[AnyRef] = {
+    val slot = args.checkInteger(0)
+    val nonEmpty = data.getStackInSlot(slot) != null
+    data.setInventorySlotContents(slot, null)
+    result(nonEmpty)
+  }
+
+  @Callback(doc = "function(fromSlot:number, toSlot:number[, address:string]):boolean -- Copies an entry to another slot, optionally to another database. Returns true if something was overwritten.")
+  def copy(context: Context, args: Arguments): Array[AnyRef] = {
+    val fromSlot = args.checkSlot(data, 0)
+    val entry = data.getStackInSlot(fromSlot)
+    def set(inventory: IInventory) = {
+      val toSlot = args.checkSlot(inventory, 1)
+      val nonEmpty = inventory.getStackInSlot(toSlot) != null
+      inventory.setInventorySlotContents(toSlot, entry)
+      result(nonEmpty)
+    }
+    if (args.count > 2) withDatabase(args.checkString(2), database => set(database.data))
+    else set(data)
+  }
+
   @Callback(doc = "function(address:string):number -- Copies the data stored in this database to another database with the specified address.")
   def clone(context: Context, args: Arguments): Array[AnyRef] = {
-    node.network.node(args.checkString(0)) match {
+    withDatabase(args.checkString(0), database => {
-      case component: Component => component.host match {
+      val numberToCopy = math.min(data.getSizeInventory, database.data.getSizeInventory)
-        case database: UpgradeDatabase =>
+      for (slot <- 0 until numberToCopy) {
-          val numberToCopy = math.min(data.getSizeInventory, database.data.getSizeInventory)
+        database.data.setInventorySlotContents(slot, data.getStackInSlot(slot))
-          for (slot <- 0 until numberToCopy) {
-            database.data.setInventorySlotContents(slot, data.getStackInSlot(slot))
-          }
-          context.pause(0.25)
-          result(numberToCopy)
-        case _ => throw new IllegalArgumentException("not a database")
       }
-      case _ => throw new IllegalArgumentException("no such component")
+      context.pause(0.25)
-    }
+      result(numberToCopy)
+    })
   }
 
   private def indexOf(needle: String, offset: Int = 0): Int = {
@@ -63,4 +85,14 @@ class UpgradeDatabase(val data: IInventory) extends prefab.ManagedEnvironment wi
     }
     -1
   }
+
+  private def withDatabase(address: String, f: UpgradeDatabase => Array[AnyRef]): Array[AnyRef] = {
+    node.network.node(address) match {
+      case component: Component => component.host match {
+        case database: UpgradeDatabase => f(database)
+        case _ => throw new IllegalArgumentException("not a database")
+      }
+      case _ => throw new IllegalArgumentException("no such component")
+    }
+  }
 }