1 files changed, 79 insertions, 0 deletions
diff --git a/serde_v8/src/magic/value.rs b/serde_v8/src/magic/value.rs
new file mode 100644
index 000000000..2cb622466
--- /dev/null
+++ b/serde_v8/src/magic/value.rs
@@ -0,0 +1,79 @@
+// Copyright 2018-2021 the Deno authors. All rights reserved. MIT license.
+use rusty_v8 as v8;
+
+use std::fmt;
+use std::marker::PhantomData;
+
+pub const FIELD: &str = "$__v8_magic_value";
+pub const NAME: &str = "$__v8_magic_Value";
+
+/// serde_v8::Value allows passing through `v8::Value`s untouched
+/// when encoding/decoding and allows mixing rust & v8 values in
+/// structs, tuples...
+/// The implementation mainly breaks down to:
+/// 1. Transmuting between u64 <> serde_v8::Value
+/// 2. Using special struct/field names to detect these values
+/// 3. Then serde "boilerplate"
+pub struct Value<'s> {
+  pub v8_value: v8::Local<'s, v8::Value>,
+}
+
+impl<'s> From<v8::Local<'s, v8::Value>> for Value<'s> {
+  fn from(v8_value: v8::Local<'s, v8::Value>) -> Self {
+    Self { v8_value }
+  }
+}
+
+impl<'s> From<Value<'s>> for v8::Local<'s, v8::Value> {
+  fn from(v: Value<'s>) -> Self {
+    v.v8_value
+  }
+}
+
+impl serde::Serialize for Value<'_> {
+  fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+  where
+    S: serde::Serializer,
+  {
+    use serde::ser::SerializeStruct;
+
+    let mut s = serializer.serialize_struct(NAME, 1)?;
+    let mv = Value {
+      v8_value: self.v8_value,
+    };
+    let hack: u64 = unsafe { std::mem::transmute(mv) };
+    s.serialize_field(FIELD, &hack)?;
+    s.end()
+  }
+}
+
+impl<'de, 's> serde::Deserialize<'de> for Value<'s> {
+  fn deserialize<D>(deserializer: D) -> Result<Value<'s>, D::Error>
+  where
+    D: serde::Deserializer<'de>,
+  {
+    struct ValueVisitor<'s> {
+      p1: PhantomData<&'s ()>,
+    }
+
+    impl<'de, 's> serde::de::Visitor<'de> for ValueVisitor<'s> {
+      type Value = Value<'s>;
+
+      fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
+        formatter.write_str("a v8::Value")
+      }
+
+      fn visit_u64<E>(self, v: u64) -> Result<Self::Value, E>
+      where
+        E: serde::de::Error,
+      {
+        let mv: Value<'s> = unsafe { std::mem::transmute(v) };
+        Ok(mv)
+      }
+    }
+
+    static FIELDS: [&str; 1] = [FIELD];
+    let visitor = ValueVisitor { p1: PhantomData };
+    deserializer.deserialize_struct(NAME, &FIELDS, visitor)
+  }
+}