1 files changed, 142 insertions, 0 deletions
diff --git a/serde_v8/serializable.rs b/serde_v8/serializable.rs
new file mode 100644
index 000000000..533b3f83f
--- /dev/null
+++ b/serde_v8/serializable.rs
@@ -0,0 +1,142 @@
+// Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.
+use std::any::TypeId;
+use std::mem::transmute_copy;
+
+use crate::Buffer;
+use crate::ByteString;
+use crate::U16String;
+
+/// Serializable exists to allow boxing values as "objects" to be serialized later,
+/// this is particularly useful for async op-responses. This trait is a more efficient
+/// replacement for erased-serde that makes less allocations, since it's specific to serde_v8
+/// (and thus doesn't have to have generic outputs, etc...)
+pub trait Serializable {
+  fn to_v8<'a>(
+    &self,
+    scope: &mut v8::HandleScope<'a>,
+  ) -> Result<v8::Local<'a, v8::Value>, crate::Error>;
+}
+
+/// Allows all implementors of `serde::Serialize` to implement Serializable
+impl<T: serde::Serialize> Serializable for T {
+  fn to_v8<'a>(
+    &self,
+    scope: &mut v8::HandleScope<'a>,
+  ) -> Result<v8::Local<'a, v8::Value>, crate::Error> {
+    crate::to_v8(scope, self)
+  }
+}
+
+/// SerializablePkg exists to provide a fast path for op returns,
+/// allowing them to avoid boxing primtives (ints/floats/bool/unit/...)
+pub enum SerializablePkg {
+  Primitive(Primitive),
+  Serializable(Box<dyn Serializable>),
+}
+
+impl SerializablePkg {
+  pub fn to_v8<'a>(
+    &self,
+    scope: &mut v8::HandleScope<'a>,
+  ) -> Result<v8::Local<'a, v8::Value>, crate::Error> {
+    match &*self {
+      Self::Primitive(x) => crate::to_v8(scope, x),
+      Self::Serializable(x) => x.to_v8(scope),
+    }
+  }
+}
+
+/// Primitive serves as a lightweight serializable wrapper around primitives
+/// so that we can use them for async values
+pub enum Primitive {
+  Unit,
+  Bool(bool),
+  Int8(i8),
+  Int16(i16),
+  Int32(i32),
+  Int64(i64),
+  UInt8(u8),
+  UInt16(u16),
+  UInt32(u32),
+  UInt64(u64),
+  Float32(f32),
+  Float64(f64),
+  String(String),
+  Buffer(Buffer),
+  ByteString(ByteString),
+  U16String(U16String),
+}
+
+impl serde::Serialize for Primitive {
+  fn serialize<S>(&self, s: S) -> Result<S::Ok, S::Error>
+  where
+    S: serde::Serializer,
+  {
+    match self {
+      Self::Unit => ().serialize(s),
+      Self::Bool(x) => x.serialize(s),
+      Self::Int8(x) => x.serialize(s),
+      Self::Int16(x) => x.serialize(s),
+      Self::Int32(x) => x.serialize(s),
+      Self::Int64(x) => x.serialize(s),
+      Self::UInt8(x) => x.serialize(s),
+      Self::UInt16(x) => x.serialize(s),
+      Self::UInt32(x) => x.serialize(s),
+      Self::UInt64(x) => x.serialize(s),
+      Self::Float32(x) => x.serialize(s),
+      Self::Float64(x) => x.serialize(s),
+      Self::String(x) => x.serialize(s),
+      Self::Buffer(x) => x.serialize(s),
+      Self::ByteString(x) => x.serialize(s),
+      Self::U16String(x) => x.serialize(s),
+    }
+  }
+}
+
+impl<T: serde::Serialize + 'static> From<T> for SerializablePkg {
+  fn from(x: T) -> Self {
+    #[inline(always)]
+    fn tc<T, U>(src: T) -> U {
+      let x = unsafe { transmute_copy(&src) };
+      std::mem::forget(src);
+      x
+    }
+
+    let tid = TypeId::of::<T>();
+    if tid == TypeId::of::<()>() {
+      Self::Primitive(Primitive::Unit)
+    } else if tid == TypeId::of::<bool>() {
+      Self::Primitive(Primitive::Bool(tc(x)))
+    } else if tid == TypeId::of::<i8>() {
+      Self::Primitive(Primitive::Int8(tc(x)))
+    } else if tid == TypeId::of::<i16>() {
+      Self::Primitive(Primitive::Int16(tc(x)))
+    } else if tid == TypeId::of::<i32>() {
+      Self::Primitive(Primitive::Int32(tc(x)))
+    } else if tid == TypeId::of::<i64>() {
+      Self::Primitive(Primitive::Int64(tc(x)))
+    } else if tid == TypeId::of::<u8>() {
+      Self::Primitive(Primitive::UInt8(tc(x)))
+    } else if tid == TypeId::of::<u16>() {
+      Self::Primitive(Primitive::UInt16(tc(x)))
+    } else if tid == TypeId::of::<u32>() {
+      Self::Primitive(Primitive::UInt32(tc(x)))
+    } else if tid == TypeId::of::<u64>() {
+      Self::Primitive(Primitive::UInt64(tc(x)))
+    } else if tid == TypeId::of::<f32>() {
+      Self::Primitive(Primitive::Float32(tc(x)))
+    } else if tid == TypeId::of::<f64>() {
+      Self::Primitive(Primitive::Float64(tc(x)))
+    } else if tid == TypeId::of::<String>() {
+      Self::Primitive(Primitive::String(tc(x)))
+    } else if tid == TypeId::of::<Buffer>() {
+      Self::Primitive(Primitive::Buffer(tc(x)))
+    } else if tid == TypeId::of::<ByteString>() {
+      Self::Primitive(Primitive::ByteString(tc(x)))
+    } else if tid == TypeId::of::<U16String>() {
+      Self::Primitive(Primitive::U16String(tc(x)))
+    } else {
+      Self::Serializable(Box::new(x))
+    }
+  }
+}