From e2b5fbd054954424dcd6391da561160d37ec7c86 Mon Sep 17 00:00:00 2001
From: mworzala <mattheworzala@gmail.com>
Date: Sat, 18 Mar 2023 09:13:51 -0400
Subject: [PATCH] hollow-cube/tag-transient

Signed-off-by: mworzala <mattheworzala@gmail.com>

allow null tag entries

(cherry picked from commit 0a57fd346bcb8bb966f866b6943fb2e57845c110)

allow null tag entries

(cherry picked from commit 3ef62831603163c2ac13432e3f2dd8ffebfb5fef)

add Tag.Transient

(cherry picked from commit 9fbbe563c2dce1418a66d2ed8695a4309807c084)

(cherry picked from commit 207b658bcd5331f3a634a2bf9cfef30280a921eb)
---
 .../net/minestom/server/tag/Serializers.java  |  2 ++
 .../java/net/minestom/server/tag/Tag.java     |  5 +++
 .../minestom/server/tag/TagHandlerImpl.java   |  5 +--
 .../minestom/server/tag/TagTransientTest.java | 32 +++++++++++++++++++
 4 files changed, 42 insertions(+), 2 deletions(-)
 create mode 100644 src/test/java/net/minestom/server/tag/TagTransientTest.java

diff --git a/src/main/java/net/minestom/server/tag/Serializers.java b/src/main/java/net/minestom/server/tag/Serializers.java
index fb46b8190..0266a123a 100644
--- a/src/main/java/net/minestom/server/tag/Serializers.java
+++ b/src/main/java/net/minestom/server/tag/Serializers.java
@@ -30,6 +30,8 @@ final class Serializers {
     static final Entry<Component, NBTString> COMPONENT = new Entry<>(NBTType.TAG_String, input -> GsonComponentSerializer.gson().deserialize(input.getValue()),
             component -> NBT.String(GsonComponentSerializer.gson().serialize(component)));
 
+    static final Entry<Object, NBTByte> EMPTY = new Entry<>(NBTType.TAG_Byte, unused -> null, component -> null);
+
     static <T> Entry<T, NBTCompound> fromTagSerializer(TagSerializer<T> serializer) {
         return new Serializers.Entry<>(NBTType.TAG_Compound,
                 (NBTCompound compound) -> {
diff --git a/src/main/java/net/minestom/server/tag/Tag.java b/src/main/java/net/minestom/server/tag/Tag.java
index dee669f0f..807cc3678 100644
--- a/src/main/java/net/minestom/server/tag/Tag.java
+++ b/src/main/java/net/minestom/server/tag/Tag.java
@@ -319,4 +319,9 @@ public class Tag<T> {
     public static <T extends Record> @NotNull Tag<T> View(@NotNull Class<T> type) {
         return View(TagRecord.serializer(type));
     }
+
+    public static <T> @NotNull Tag<T> Transient(@NotNull String key) {
+        //noinspection unchecked
+        return (Tag<T>) tag(key, Serializers.EMPTY);
+    }
 }
diff --git a/src/main/java/net/minestom/server/tag/TagHandlerImpl.java b/src/main/java/net/minestom/server/tag/TagHandlerImpl.java
index 67ec75db6..03dc1211c 100644
--- a/src/main/java/net/minestom/server/tag/TagHandlerImpl.java
+++ b/src/main/java/net/minestom/server/tag/TagHandlerImpl.java
@@ -281,7 +281,7 @@ final class TagHandlerImpl implements TagHandler {
                 this.entries.forValues(entry -> {
                     final Tag tag = entry.tag;
                     final NBT nbt = entry.updatedNbt();
-                    if (!tag.entry.isPath() || (!Serializers.SERIALIZE_EMPTY_COMPOUND) && !((NBTCompound) nbt).isEmpty()) {
+                    if (nbt != null && !tag.entry.isPath() || (!Serializers.SERIALIZE_EMPTY_COMPOUND) && !((NBTCompound) nbt).isEmpty()) {
                         tmp.put(tag.getKey(), nbt);
                     }
                 });
@@ -310,7 +310,8 @@ final class TagHandlerImpl implements TagHandler {
                     nbt = entry.updatedNbt();
                 }
 
-                tmp.put(tag.getKey(), nbt);
+                if (nbt != null)
+                    tmp.put(tag.getKey(), nbt);
                 entries.put(tag.index, valueToEntry(result, tag, value));
             });
             if ((!Serializers.SERIALIZE_EMPTY_COMPOUND) && tmp.isEmpty() && parent != null)
diff --git a/src/test/java/net/minestom/server/tag/TagTransientTest.java b/src/test/java/net/minestom/server/tag/TagTransientTest.java
new file mode 100644
index 000000000..dcaee6727
--- /dev/null
+++ b/src/test/java/net/minestom/server/tag/TagTransientTest.java
@@ -0,0 +1,32 @@
+package net.minestom.server.tag;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
+
+public class TagTransientTest {
+
+    @Test
+    public void twoTransientTags() {
+        var tagHandler = TagHandler.newHandler();
+        Tag<String> tag1 = Tag.Transient("a");
+        Tag<String> tag2 = Tag.Transient("b");
+
+        tagHandler.setTag(tag1, "abcdef");
+        var result = tagHandler.getTag(tag2);
+        assertNull(result);
+    }
+
+    @Test
+    public void twoTransientTagsEqual() {
+        var tagHandler = TagHandler.newHandler();
+        Tag<String> tag1 = Tag.Transient("a");
+        Tag<String> tag2 = Tag.Transient("a");
+
+        tagHandler.setTag(tag1, "abcdef");
+        var result = tagHandler.getTag(tag2);
+        assertEquals("abcdef", result);
+    }
+
+}