1 files changed, 118 insertions, 0 deletions
diff --git a/serde_v8/src/serializable.rs b/serde_v8/src/serializable.rs
new file mode 100644
index 000000000..c9182b636
--- /dev/null
+++ b/serde_v8/src/serializable.rs
@@ -0,0 +1,118 @@
+// Copyright 2018-2021 the Deno authors. All rights reserved. MIT license.
+use rusty_v8 as v8;
+use std::any::TypeId;
+use std::mem::transmute_copy;
+
+/// 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
+#[derive(Clone, Copy)]
+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),
+}
+
+impl serde::Serialize for Primitive {
+  fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+  where
+    S: serde::Serializer,
+  {
+    match *self {
+      Self::Unit => serializer.serialize_unit(),
+      Self::Bool(x) => serializer.serialize_bool(x),
+      Self::Int8(x) => serializer.serialize_i8(x),
+      Self::Int16(x) => serializer.serialize_i16(x),
+      Self::Int32(x) => serializer.serialize_i32(x),
+      Self::Int64(x) => serializer.serialize_i64(x),
+      Self::UInt8(x) => serializer.serialize_u8(x),
+      Self::UInt16(x) => serializer.serialize_u16(x),
+      Self::UInt32(x) => serializer.serialize_u32(x),
+      Self::UInt64(x) => serializer.serialize_u64(x),
+      Self::Float32(x) => serializer.serialize_f32(x),
+      Self::Float64(x) => serializer.serialize_f64(x),
+    }
+  }
+}
+
+impl<T: serde::Serialize + 'static> From<T> for SerializablePkg {
+  fn from(x: T) -> Self {
+    let tid = TypeId::of::<T>();
+
+    if tid == TypeId::of::<()>() {
+      Self::Primitive(Primitive::Unit)
+    } else if tid == TypeId::of::<bool>() {
+      Self::Primitive(Primitive::Bool(unsafe { transmute_copy(&x) }))
+    } else if tid == TypeId::of::<i8>() {
+      Self::Primitive(Primitive::Int8(unsafe { transmute_copy(&x) }))
+    } else if tid == TypeId::of::<i16>() {
+      Self::Primitive(Primitive::Int16(unsafe { transmute_copy(&x) }))
+    } else if tid == TypeId::of::<i32>() {
+      Self::Primitive(Primitive::Int32(unsafe { transmute_copy(&x) }))
+    } else if tid == TypeId::of::<i64>() {
+      Self::Primitive(Primitive::Int64(unsafe { transmute_copy(&x) }))
+    } else if tid == TypeId::of::<u8>() {
+      Self::Primitive(Primitive::UInt8(unsafe { transmute_copy(&x) }))
+    } else if tid == TypeId::of::<u16>() {
+      Self::Primitive(Primitive::UInt16(unsafe { transmute_copy(&x) }))
+    } else if tid == TypeId::of::<u32>() {
+      Self::Primitive(Primitive::UInt32(unsafe { transmute_copy(&x) }))
+    } else if tid == TypeId::of::<u64>() {
+      Self::Primitive(Primitive::UInt64(unsafe { transmute_copy(&x) }))
+    } else if tid == TypeId::of::<f32>() {
+      Self::Primitive(Primitive::Float32(unsafe { transmute_copy(&x) }))
+    } else if tid == TypeId::of::<f64>() {
+      Self::Primitive(Primitive::Float64(unsafe { transmute_copy(&x) }))
+    } else {
+      Self::Serializable(Box::new(x))
+    }
+  }
+}