refactor: replace toNbt with getExtras in ItemMeta and update related logic

Author: wu-vincent

include/endstone/inventory/meta/item_meta.h

@@ -22,11 +22,13 @@
 #include <vector>
 
 #include "endstone/enchantments/enchantment.h"
-#include "endstone/nbt/tag.h"
 
 #define ENDSTONE_ITEM_META_TYPE(type) static constexpr auto MetaType = Type::type;
 
 namespace endstone {
+namespace core {
+class ItemMetaExtras;
+}
 /**
  * @brief Represents the metadata of a generic item.
  */
@@ -219,7 +221,10 @@ class ItemMeta {
      */
     [[nodiscard]] virtual std::unique_ptr<ItemMeta> clone() const = 0;
 
-    [[nodiscard]] virtual CompoundTag toNbt() const = 0;
+    /**
+     * @internal Internal use only.
+     */
+    [[nodiscard]] virtual const core::ItemMetaExtras &getExtras() const = 0;
 
     template <typename T>
         requires std::is_base_of_v<ItemMeta, T>

src/bedrock/nbt/compound_tag.cpp

@@ -231,6 +231,16 @@ const Int64Tag *CompoundTag::getInt64Tag(StringView name) const
     return nullptr;
 }
 
+Int64Tag *CompoundTag::getInt64Tag(StringView name)
+{
+    if (auto *tag = get(name); tag) {
+        if (tag->getId() == Type::Int64) {
+            return static_cast<Int64Tag *>(tag);
+        }
+    }
+    return nullptr;
+}
+
 std::int16_t CompoundTag::getShort(StringView name) const
 {
     if (const auto *tag = getShortTag(name)) {

src/endstone/core/inventory/inventory.cpp

@@ -32,7 +32,7 @@ int EndstoneInventory::getMaxStackSize() const
 
 std::optional<ItemStack> EndstoneInventory::getItem(int index) const
 {
-    auto item = container_.getItem(index);
+    const auto &item = container_.getItem(index);
     if (item.isNull()) {
         return std::nullopt;
     }

src/endstone/core/inventory/item_factory.cpp

@@ -36,12 +36,14 @@ bool EndstoneItemFactory::isApplicable(const ItemMeta *meta, const ItemTypeId ty
     if (meta == nullptr) {
         return false;
     }
-    return static_cast<const EndstoneItemMeta &>(*meta).applicableTo(type);
+    return meta->getExtras().applicableTo(type);
 }
 
-static bool equals0(const EndstoneItemMeta &meta1, const EndstoneItemMeta &meta2)
+static bool equals0(const ItemMeta &meta1, const ItemMeta &meta2)
 {
-    return meta1.equalsCommon(meta2) && meta1.notUncommon(meta2) && meta2.notUncommon(meta1);
+    auto &e1 = meta1.getExtras();
+    auto &e2 = meta2.getExtras();
+    return e1.equalsCommon(meta2) && e1.notUncommon(meta2) && e2.notUncommon(meta1);
 }
 
 bool EndstoneItemFactory::equals(const ItemMeta *meta1, const ItemMeta *meta2) const
@@ -50,12 +52,12 @@ bool EndstoneItemFactory::equals(const ItemMeta *meta1, const ItemMeta *meta2) c
         return true;
     }
     if (meta1 == nullptr) {
-        return static_cast<const EndstoneItemMeta *>(meta2)->isEmpty();
+        return meta2->getExtras().isEmpty();
     }
     if (meta2 == nullptr) {
-        return static_cast<const EndstoneItemMeta *>(meta1)->isEmpty();
+        return meta1->getExtras().isEmpty();
     }
-    return equals0(static_cast<const EndstoneItemMeta &>(*meta1), static_cast<const EndstoneItemMeta &>(*meta2));
+    return equals0(*meta1, *meta2);
 }
 
 std::unique_ptr<ItemMeta> EndstoneItemFactory::asMetaFor(const ItemMeta *meta, ItemTypeId type) const

src/endstone/core/inventory/item_stack.cpp

@@ -21,6 +21,7 @@
 #include "endstone/core/nbt.h"
 
 namespace endstone::core {
+
 EndstoneItemStack::EndstoneItemStack(const ::ItemStackBase &item) : item_(item) {}
 
 EndstoneItemStack::EndstoneItemStack(const EndstoneItemStack &other) : item_(other.item_) {}
@@ -200,7 +201,7 @@ bool EndstoneItemStack::setItemMeta(ItemStackBase *item, const ItemMeta *meta)
         return true;
     }
 
-    if (const auto &m = static_cast<EndstoneItemMeta &>(*item_meta); !m.isEmpty()) {
+    if (auto &m = item_meta->getExtras(); !m.isEmpty()) {
         auto tag = item->hasUserData() ? item->getUserData()->clone() : std::make_unique<::CompoundTag>();
         m.applyToItem(*tag);
         item->setUserData(std::move(tag));

src/endstone/core/inventory/meta/item_meta.h

@@ -181,12 +181,7 @@ class EndstoneItemMetaBase : public Interface, public ItemMetaExtras {
 
     void setRepairCost(int cost) override { repair_cost_ = cost; }
 
-    [[nodiscard]] CompoundTag toNbt() const override
-    {
-        auto tag = std::make_unique<::CompoundTag>();
-        applyToItem(*tag);
-        return nbt::fromMinecraft(*tag).get<CompoundTag>();
-    }
+    [[nodiscard]] const ItemMetaExtras &getExtras() const override { return *this; }
 
     [[nodiscard]] bool isEmpty() const override
     {