Create MinecraftObjectMarker.kt

src/main/kotlin/net/axay/kspigot/utils/MinecraftObjectMarker.kt

@@ -0,0 +1,50 @@
+package net.axay.kspigot.utils
+
+import net.axay.kspigot.extensions.pluginKey
+import net.axay.kspigot.items.meta
+import org.bukkit.inventory.ItemStack
+import org.bukkit.persistence.PersistentDataHolder
+import org.bukkit.persistence.PersistentDataType
+
+private fun markerKey(key: String) = pluginKey("kspigot_marker_$key")
+
+/**
+ * Marks this object with the given [key].
+ * This is persistent.
+ *
+ * This function makes sure that there are no
+ * conflicts with other plugins, therefore even simple
+ * keys are safe.
+ */
+fun PersistentDataHolder.mark(key: String) {
+    persistentDataContainer[markerKey(key), PersistentDataType.BYTE] = 1.toByte()
+}
+
+/**
+ * Removes the given [key] from this objects'
+ * markings.
+ */
+fun PersistentDataHolder.unmark(key: String) {
+    persistentDataContainer.remove(markerKey(key))
+}
+
+/**
+ * @return True, if the given [key] is among
+ * this objects' markings.
+ */
+fun PersistentDataHolder.hasMark(key: String) = persistentDataContainer.has(markerKey(key), PersistentDataType.BYTE)
+
+// quick access for ItemStacks
+
+/** @see PersistentDataHolder.mark */
+fun ItemStack.mark(key: String) = meta { mark(key) }
+
+/** @see PersistentDataHolder.unmark */
+fun ItemStack.unmark(key: String) = meta { unmark(key) }
+
+/** @see PersistentDataHolder.hasMark */
+fun ItemStack.hasMark(key: String): Boolean {
+    var result: Boolean = false
+    meta { result = hasMark(key) }
+    return result
+}