Add extremely simple item NBT tags

<i@item.has_nbt[<key>]>, <i@item.nbt_keys[<filter>]>,
<i@item.nbt[<key>]>

src/main/java/net/aufdemrand/denizen/Denizen.java

@@ -813,6 +813,7 @@ public void onEnable() {
             propertyParser.registerProperty(ItemFlags.class, dItem.class);
             propertyParser.registerProperty(ItemLore.class, dItem.class);
             propertyParser.registerProperty(ItemMap.class, dItem.class);
+            propertyParser.registerProperty(ItemNBT.class, dItem.class);
             propertyParser.registerProperty(ItemPatterns.class, dItem.class);
             propertyParser.registerProperty(ItemPlantgrowth.class, dItem.class);
             propertyParser.registerProperty(ItemPotion.class, dItem.class);

src/main/java/net/aufdemrand/denizen/objects/properties/item/ItemNBT.java

@@ -0,0 +1,97 @@
+package net.aufdemrand.denizen.objects.properties.item;
+
+import net.aufdemrand.denizen.objects.dItem;
+import net.aufdemrand.denizen.utilities.nbt.CustomNBT;
+import net.aufdemrand.denizencore.objects.Element;
+import net.aufdemrand.denizencore.objects.Mechanism;
+import net.aufdemrand.denizencore.objects.dList;
+import net.aufdemrand.denizencore.objects.dObject;
+import net.aufdemrand.denizencore.objects.properties.Property;
+import net.aufdemrand.denizencore.tags.Attribute;
+
+public class ItemNBT implements Property {
+
+    public static boolean describes(dObject item) {
+        return item instanceof dItem;
+    }
+
+    public static ItemNBT getFrom(dObject item) {
+        if (!describes(item)) {
+            return null;
+        }
+        else {
+            return new ItemNBT((dItem) item);
+        }
+    }
+
+    private ItemNBT(dItem item) {
+        this.item = item;
+    }
+
+    dItem item;
+
+    @Override
+    public String getAttribute(Attribute attribute) {
+
+        if (attribute == null) {
+            return null;
+        }
+
+        // <--[tag]
+        // @attribute <i@item.has_nbt[<key>]>
+        // @returns Element(Boolean)
+        // @group properties
+        // @description
+        // Returns whether this item has the specified NBT key.
+        // -->
+        if (attribute.startsWith("has_nbt")) {
+            return new Element(CustomNBT.hasCustomNBT(item.getItemStack(), attribute.getContext(1)))
+                    .getAttribute(attribute.fulfill(1));
+        }
+
+        // <--[tag]
+        // @attribute <i@item.nbt_keys[<filter>]>
+        // @returns dList
+        // @group properties
+        // @description
+        // Returns all of this item's NBT keys as a dList. Optionally, specify
+        // a filter for the start of the keys.
+        // -->
+        if (attribute.startsWith("nbt_keys")) {
+            String filter = attribute.hasContext(1) ? attribute.getContext(1) : "";
+            return new dList(CustomNBT.listNBT(item.getItemStack(), filter))
+                    .getAttribute(attribute.fulfill(1));
+        }
+
+        // <--[tag]
+        // @attribute <i@item.nbt[<key>]>
+        // @returns Element
+        // @group properties
+        // @description
+        // Returns the value of this item's NBT key as a string Element as best it can.
+        // -->
+        if (attribute.startsWith("nbt")) {
+            return new Element(CustomNBT.getCustomNBT(item.getItemStack(), attribute.getContext(1)))
+                    .getAttribute(attribute.fulfill(1));
+        }
+
+        return null;
+    }
+
+
+    @Override
+    public String getPropertyString() {
+        // TODO: list Denizen command-created NBT if/when that is added?
+        return null;
+    }
+
+    @Override
+    public String getPropertyId() {
+        return "nbt";
+    }
+
+    @Override
+    public void adjust(Mechanism mechanism) {
+        // Do nothing
+    }
+}

src/main/java/net/aufdemrand/denizen/utilities/nbt/CustomNBT.java

@@ -1,13 +1,22 @@
 package net.aufdemrand.denizen.utilities.nbt;
 
+import net.aufdemrand.denizencore.objects.Element;
+import net.aufdemrand.denizencore.utilities.CoreUtilities;
 import net.minecraft.server.v1_9_R1.EntityLiving;
+import net.minecraft.server.v1_9_R1.NBTBase;
 import net.minecraft.server.v1_9_R1.NBTTagCompound;
+import net.minecraft.server.v1_9_R1.NBTTagString;
 import org.bukkit.craftbukkit.v1_9_R1.entity.CraftEntity;
 import org.bukkit.craftbukkit.v1_9_R1.inventory.CraftItemStack;
 import org.bukkit.entity.Entity;
 import org.bukkit.entity.LivingEntity;
 import org.bukkit.inventory.ItemStack;
 
+import java.util.ArrayList;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Set;
+
 public class CustomNBT {
 
     public static MapOfEnchantments getEnchantments(ItemStack item) {
@@ -23,15 +32,18 @@ public static boolean hasCustomNBT(ItemStack item, String key) {
         if (item == null) {
             return false;
         }
-        NBTTagCompound tag;
         net.minecraft.server.v1_9_R1.ItemStack cis = CraftItemStack.asNMSCopy(item);
         if (!cis.hasTag()) {
             return false;
         }
-        tag = cis.getTag();
-        // dB.echoDebug(tag.toString());
-        // if this item has the NBTData for 'owner', there is an engraving.
-        return tag.hasKey(key);
+        key = CoreUtilities.toLowerCase(key);
+        List<String> keys = listNBT(item, "");
+        for (String string : keys) {
+            if (CoreUtilities.toLowerCase(string).equals(key)) {
+                return true;
+            }
+        }
+        return false;
     }
 
     public static String getCustomNBT(ItemStack item, String key) {
@@ -44,9 +56,41 @@ public static String getCustomNBT(ItemStack item, String key) {
             cis.setTag(new NBTTagCompound());
         }
         tag = cis.getTag();
-        // if this item has the NBTData for 'owner', return the value, which is the playername of the 'owner'.
-        if (tag.hasKey(key)) {
-            return tag.getString(key);
+        key = CoreUtilities.toLowerCase(key);
+        String finalKey = null;
+        List<String> keys = listNBT(item, "");
+        for (String string : keys) {
+            if (CoreUtilities.toLowerCase(string).equals(key)) {
+                finalKey = string;
+                break;
+            }
+        }
+        if (finalKey == null) {
+            return null;
+        }
+        Iterator<String> subkeys = CoreUtilities.split(finalKey, '.').iterator();
+        if (subkeys.hasNext()) {
+            while (true) {
+                String subkey = subkeys.next();
+                NBTBase base = tag.get(subkey);
+                if (!subkeys.hasNext()) {
+                    if (base instanceof NBTTagString) {
+                        return ((NBTTagString) base).a_();
+                    }
+                    else if (base instanceof NBTBase.NBTNumber) {
+                        return new Element(((NBTBase.NBTNumber) base).h()).asString();
+                    }
+                    else {
+                        return base.toString();
+                    }
+                }
+                else if (base instanceof NBTTagCompound) {
+                    tag = (NBTTagCompound) base;
+                }
+                else {
+                    return null;
+                }
+            }
         }
         return null;
 
@@ -62,11 +106,64 @@ public static ItemStack removeCustomNBT(ItemStack item, String key) {
             cis.setTag(new NBTTagCompound());
         }
         tag = cis.getTag();
-        // remove 'owner' NBTData
-        tag.remove(key);
+        key = CoreUtilities.toLowerCase(key);
+        String finalKey = null;
+        List<String> keys = listNBT(item, "");
+        for (String string : keys) {
+            if (CoreUtilities.toLowerCase(string).equals(key)) {
+                finalKey = string;
+                break;
+            }
+        }
+        if (finalKey == null) {
+            return null;
+        }
+        Iterator<String> subkeys = CoreUtilities.split(finalKey, '.').iterator();
+        if (subkeys.hasNext()) {
+            while (true) {
+                String subkey = subkeys.next();
+                if (!subkeys.hasNext()) {
+                    tag.remove(subkey);
+                }
+                else if (tag.get(subkey).getTypeId() == tag.getTypeId()) {
+                    tag = tag.getCompound(subkey);
+                    continue;
+                }
+                break;
+            }
+        }
         return CraftItemStack.asCraftMirror(cis);
     }
 
+    public static List<String> listNBT(ItemStack item, String filter) {
+        if (item == null) {
+            return null;
+        }
+        net.minecraft.server.v1_9_R1.ItemStack cis = CraftItemStack.asNMSCopy(item);
+        NBTTagCompound tag;
+        if (!cis.hasTag()) {
+            cis.setTag(new NBTTagCompound());
+        }
+        tag = cis.getTag();
+        return recursiveSearch(tag, "", filter);
+    }
+
+    private static List<String> recursiveSearch(NBTTagCompound compound, String base, String filter) {
+        Set<String> keys = compound.c();
+        List<String> finalKeys = new ArrayList<String>();
+        filter = CoreUtilities.toLowerCase(filter);
+        for (String key : keys) {
+            String full = base + key;
+            if (CoreUtilities.toLowerCase(full).startsWith(filter)) {
+                finalKeys.add(full);
+            }
+            if (compound.get(key).getTypeId() == compound.getTypeId()) {
+                finalKeys.addAll(recursiveSearch(compound.getCompound(key), full + ".", filter));
+            }
+        }
+        return finalKeys;
+    }
+
     public static ItemStack addCustomNBT(ItemStack item, String key, String value) {
         if (item == null) {
             return null;