add NbtTag::read_optional

simdnbt/Cargo.toml

@@ -23,6 +23,8 @@ fastnbt = "2.4.4"
 azalea-nbt = { git = "https://github.com/azalea-rs/azalea", rev = "84e036ce3752ecf57904b0f5aff1f33d43e95a32" }
 hematite-nbt = { version = "0.5.2", default-features = false }
 
+tikv-jemallocator = "0.5"
+
 [features]
 default = ["derive"]
 derive = ["dep:simdnbt-derive"]

simdnbt/benches/nbt.rs

@@ -46,8 +46,11 @@ fn bench_file(filename: &str, c: &mut Criterion) {
     group.finish();
 }
 
+#[global_allocator]
+static GLOBAL: tikv_jemallocator::Jemalloc = tikv_jemallocator::Jemalloc;
+
 fn bench(c: &mut Criterion) {
-    // bench_file("bigtest.nbt", c);
+    bench_file("bigtest.nbt", c);
     // bench_file("simple_player.dat", c);
     bench_file("complex_player.dat", c);
     // bench_file("level.dat", c);

simdnbt/src/borrow/mod.rs

@@ -170,6 +170,14 @@ impl<'a> NbtTag<'a> {
         Self::read_with_type(data, tag_type, 0)
     }
 
+    pub fn read_optional(data: &mut Cursor<&'a [u8]>) -> Result<Option<Self>, Error> {
+        let tag_type = data.read_u8().map_err(|_| Error::UnexpectedEof)?;
+        if tag_type == END_ID {
+            return Ok(None);
+        }
+        Ok(Some(Self::read_with_type(data, tag_type, 0)?))
+    }
+
     pub fn byte(&self) -> Option<i8> {
         match self {
             NbtTag::Byte(byte) => Some(*byte),

simdnbt/src/owned/mod.rs

@@ -264,6 +264,14 @@ impl NbtTag {
         Self::read_with_type(data, tag_type, 0)
     }
 
+    pub fn read_optional(data: &mut Cursor<&[u8]>) -> Result<Option<Self>, Error> {
+        let tag_type = data.read_u8().map_err(|_| Error::UnexpectedEof)?;
+        if tag_type == END_ID {
+            return Ok(None);
+        }
+        Ok(Some(Self::read_with_type(data, tag_type, 0)?))
+    }
+
     /// Write to the data without checking that there's enough space in it.
     ///
     /// # Safety