feat(serde_v8): support BigInt serialization (#18225)

This commit enables serializing `v8::BigInt` to `num_bigint::BigInt`
in Rust.

Pre-requisite for sub upcoming feature work.

10 files changed, 216 insertions, 0 deletions

diff --git a/serde_v8/Cargo.toml b/serde_v8/Cargo.toml
index 4e518e71d..a146d5ada 100644
--- a/serde_v8/Cargo.toml
+++ b/serde_v8/Cargo.toml
@@ -16,6 +16,7 @@ path = "lib.rs"
 [dependencies]
 bytes.workspace = true
 derive_more = "0.99.17"
+num-bigint.workspace = true
 serde.workspace = true
 serde_bytes.workspace = true
 smallvec = { workspace = true, features = ["union"] }
diff --git a/serde_v8/de.rs b/serde_v8/de.rs
index 15a90a13d..6708daa4d 100644
--- a/serde_v8/de.rs
+++ b/serde_v8/de.rs
@@ -13,6 +13,7 @@ use crate::magic::transl8::visit_magic;
 use crate::magic::transl8::FromV8;
 use crate::magic::transl8::MagicType;
 use crate::payload::ValueType;
+use crate::BigInt;
 use crate::ByteString;
 use crate::DetachedBuffer;
 use crate::StringOrBuffer;
@@ -348,6 +349,9 @@ impl<'de, 'a, 'b, 's, 'x> de::Deserializer<'de>
       StringOrBuffer::MAGIC_NAME => {
         visit_magic(visitor, StringOrBuffer::from_v8(self.scope, self.input)?)
       }
+      BigInt::MAGIC_NAME => {
+        visit_magic(visitor, BigInt::from_v8(self.scope, self.input)?)
+      }
       magic::Value::MAGIC_NAME => {
         visit_magic(visitor, magic::Value::from_v8(self.scope, self.input)?)
       }
diff --git a/serde_v8/error.rs b/serde_v8/error.rs
index 145524abb..72d3cc925 100644
--- a/serde_v8/error.rs
+++ b/serde_v8/error.rs
@@ -23,6 +23,7 @@ pub enum Error {
   ExpectedBuffer,
   ExpectedDetachable,
   ExpectedExternal,
+  ExpectedBigInt,
 
   ExpectedUtf8,
   ExpectedLatin1,
diff --git a/serde_v8/lib.rs b/serde_v8/lib.rs
index b857acbe8..1d17914bb 100644
--- a/serde_v8/lib.rs
+++ b/serde_v8/lib.rs
@@ -15,6 +15,7 @@ pub use de::Deserializer;
 pub use error::Error;
 pub use error::Result;
 pub use keys::KeyCache;
+pub use magic::bigint::BigInt;
 pub use magic::buffer::ZeroCopyBuf;
 pub use magic::bytestring::ByteString;
 pub use magic::detached_buffer::DetachedBuffer;
diff --git a/serde_v8/magic/bigint.rs b/serde_v8/magic/bigint.rs
new file mode 100644
index 000000000..69828747f
--- /dev/null
+++ b/serde_v8/magic/bigint.rs
@@ -0,0 +1,76 @@
+// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
+
+use smallvec::smallvec;
+use smallvec::SmallVec;
+
+use super::transl8::FromV8;
+use super::transl8::ToV8;
+use crate::magic::transl8::impl_magic;
+use crate::Error;
+
+#[derive(
+  PartialEq,
+  Eq,
+  Clone,
+  Debug,
+  Default,
+  derive_more::Deref,
+  derive_more::DerefMut,
+  derive_more::AsRef,
+  derive_more::AsMut,
+)]
+#[as_mut(forward)]
+#[as_ref(forward)]
+pub struct BigInt(num_bigint::BigInt);
+impl_magic!(BigInt);
+
+impl ToV8 for BigInt {
+  fn to_v8<'a>(
+    &mut self,
+    scope: &mut v8::HandleScope<'a>,
+  ) -> Result<v8::Local<'a, v8::Value>, crate::Error> {
+    let (sign, words) = self.0.to_u64_digits();
+    let sign_bit = sign == num_bigint::Sign::Minus;
+    let v = v8::BigInt::new_from_words(scope, sign_bit, &words).unwrap();
+    Ok(v.into())
+  }
+}
+
+impl FromV8 for BigInt {
+  fn from_v8(
+    _scope: &mut v8::HandleScope,
+    value: v8::Local<v8::Value>,
+  ) -> Result<Self, crate::Error> {
+    let v8bigint = v8::Local::<v8::BigInt>::try_from(value)
+      .map_err(|_| Error::ExpectedBigInt)?;
+    let word_count = v8bigint.word_count();
+    let mut words: SmallVec<[u64; 1]> = smallvec![0u64; word_count];
+    let (sign_bit, _words) = v8bigint.to_words_array(&mut words);
+    let sign = match sign_bit {
+      true => num_bigint::Sign::Minus,
+      false => num_bigint::Sign::Plus,
+    };
+    // SAFETY: Because the alignment of u64 is 8, the alignment of u32 is 4, and
+    // the size of u64 is 8, the size of u32 is 4, the alignment of u32 is a
+    // factor of the alignment of u64, and the size of u32 is a factor of the
+    // size of u64, we can safely transmute the slice of u64 to a slice of u32.
+    let (prefix, slice, suffix) = unsafe { words.align_to::<u32>() };
+    assert!(prefix.is_empty());
+    assert!(suffix.is_empty());
+    assert_eq!(slice.len(), words.len() * 2);
+    let big_int = num_bigint::BigInt::from_slice(sign, slice);
+    Ok(Self(big_int))
+  }
+}
+
+impl From<num_bigint::BigInt> for BigInt {
+  fn from(big_int: num_bigint::BigInt) -> Self {
+    Self(big_int)
+  }
+}
+
+impl From<BigInt> for num_bigint::BigInt {
+  fn from(big_int: BigInt) -> Self {
+    big_int.0
+  }
+}
diff --git a/serde_v8/magic/mod.rs b/serde_v8/magic/mod.rs
index f96e422b1..9e5064867 100644
--- a/serde_v8/magic/mod.rs
+++ b/serde_v8/magic/mod.rs
@@ -1,4 +1,5 @@
 // Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
+pub mod bigint;
 pub mod buffer;
 pub mod bytestring;
 pub mod detached_buffer;
diff --git a/serde_v8/ser.rs b/serde_v8/ser.rs
index fa4cfecde..6c10f3fb4 100644
--- a/serde_v8/ser.rs
+++ b/serde_v8/ser.rs
@@ -14,6 +14,7 @@ use crate::magic::transl8::opaque_recv;
 use crate::magic::transl8::MagicType;
 use crate::magic::transl8::ToV8;
 use crate::magic::transl8::MAGIC_FIELD;
+use crate::BigInt;
 use crate::ByteString;
 use crate::DetachedBuffer;
 use crate::ExternalPointer;
@@ -277,6 +278,7 @@ pub enum StructSerializers<'a, 'b, 'c> {
   MagicByteString(MagicalSerializer<'a, 'b, 'c, ByteString>),
   MagicU16String(MagicalSerializer<'a, 'b, 'c, U16String>),
   MagicStringOrBuffer(MagicalSerializer<'a, 'b, 'c, StringOrBuffer>),
+  MagicBigInt(MagicalSerializer<'a, 'b, 'c, BigInt>),
   Regular(ObjectSerializer<'a, 'b, 'c>),
 }
 
@@ -299,6 +301,7 @@ impl<'a, 'b, 'c> ser::SerializeStruct for StructSerializers<'a, 'b, 'c> {
       StructSerializers::MagicStringOrBuffer(s) => {
         s.serialize_field(key, value)
       }
+      StructSerializers::MagicBigInt(s) => s.serialize_field(key, value),
       StructSerializers::Regular(s) => s.serialize_field(key, value),
     }
   }
@@ -312,6 +315,7 @@ impl<'a, 'b, 'c> ser::SerializeStruct for StructSerializers<'a, 'b, 'c> {
       StructSerializers::MagicByteString(s) => s.end(),
       StructSerializers::MagicU16String(s) => s.end(),
       StructSerializers::MagicStringOrBuffer(s) => s.end(),
+      StructSerializers::MagicBigInt(s) => s.end(),
       StructSerializers::Regular(s) => s.end(),
     }
   }
@@ -592,6 +596,10 @@ impl<'a, 'b, 'c> ser::Serializer for Serializer<'a, 'b, 'c> {
         let m = MagicalSerializer::<StringOrBuffer>::new(self.scope);
         Ok(StructSerializers::MagicStringOrBuffer(m))
       }
+      BigInt::MAGIC_NAME => {
+        let m = MagicalSerializer::<BigInt>::new(self.scope);
+        Ok(StructSerializers::MagicBigInt(m))
+      }
       magic::Value::MAGIC_NAME => {
         let m = MagicalSerializer::<magic::Value<'a>>::new(self.scope);
         Ok(StructSerializers::Magic(m))
diff --git a/serde_v8/serializable.rs b/serde_v8/serializable.rs
index 21c7bb752..b02aa0629 100644
--- a/serde_v8/serializable.rs
+++ b/serde_v8/serializable.rs
@@ -2,6 +2,7 @@
 use std::any::TypeId;
 use std::mem::transmute_copy;
 
+use crate::BigInt;
 use crate::ByteString;
 use crate::U16String;
 use crate::ZeroCopyBuf;
@@ -65,6 +66,7 @@ pub enum Primitive {
   ZeroCopyBuf(ZeroCopyBuf),
   ByteString(ByteString),
   U16String(U16String),
+  BigInt(BigInt),
 }
 
 impl serde::Serialize for Primitive {
@@ -89,6 +91,7 @@ impl serde::Serialize for Primitive {
       Self::ZeroCopyBuf(x) => x.serialize(s),
       Self::ByteString(x) => x.serialize(s),
       Self::U16String(x) => x.serialize(s),
+      Self::BigInt(x) => x.serialize(s),
     }
   }
 }
@@ -137,6 +140,8 @@ impl<T: serde::Serialize + 'static> From<T> for SerializablePkg {
       Self::Primitive(Primitive::ByteString(tc(x)))
     } else if tid == TypeId::of::<U16String>() {
       Self::Primitive(Primitive::U16String(tc(x)))
+    } else if tid == TypeId::of::<BigInt>() {
+      Self::Primitive(Primitive::BigInt(tc(x)))
     } else {
       Self::Serializable(Box::new(x))
     }
diff --git a/serde_v8/tests/de.rs b/serde_v8/tests/de.rs
index 5f3e262e7..a77089bab 100644
--- a/serde_v8/tests/de.rs
+++ b/serde_v8/tests/de.rs
@@ -4,6 +4,7 @@ use serde::Deserializer;
 
 use serde_v8::utils::js_exec;
 use serde_v8::utils::v8_do;
+use serde_v8::BigInt;
 use serde_v8::ByteString;
 use serde_v8::Error;
 use serde_v8::U16String;
@@ -566,3 +567,65 @@ detest!(
   "BigInt(-1.7976931348623157e+308)",
   f32::NEG_INFINITY
 );
+
+// BigInt to BigInt
+detest!(
+  de_bigint_var_u8,
+  BigInt,
+  "255n",
+  num_bigint::BigInt::from(255u8).into()
+);
+detest!(
+  de_bigint_var_i8,
+  BigInt,
+  "-128n",
+  num_bigint::BigInt::from(-128i8).into()
+);
+detest!(
+  de_bigint_var_u16,
+  BigInt,
+  "65535n",
+  num_bigint::BigInt::from(65535u16).into()
+);
+detest!(
+  de_bigint_var_i16,
+  BigInt,
+  "-32768n",
+  num_bigint::BigInt::from(-32768i16).into()
+);
+detest!(
+  de_bigint_var_u32,
+  BigInt,
+  "4294967295n",
+  num_bigint::BigInt::from(4294967295u32).into()
+);
+detest!(
+  de_bigint_var_i32,
+  BigInt,
+  "-2147483648n",
+  num_bigint::BigInt::from(-2147483648i32).into()
+);
+detest!(
+  de_bigint_var_u64,
+  BigInt,
+  "18446744073709551615n",
+  num_bigint::BigInt::from(18446744073709551615u64).into()
+);
+detest!(
+  de_bigint_var_i64,
+  BigInt,
+  "-9223372036854775808n",
+  num_bigint::BigInt::from(-9223372036854775808i64).into()
+);
+detest!(
+  de_bigint_var_u128,
+  BigInt,
+  "340282366920938463463374607431768211455n",
+  num_bigint::BigInt::from(340282366920938463463374607431768211455u128).into()
+);
+detest!(
+  de_bigint_var_i128,
+  BigInt,
+  "-170141183460469231731687303715884105728n",
+  num_bigint::BigInt::from(-170141183460469231731687303715884105728i128).into()
+);
diff --git a/serde_v8/tests/ser.rs b/serde_v8/tests/ser.rs
index d6de3a62a..b61a758f9 100644
--- a/serde_v8/tests/ser.rs
+++ b/serde_v8/tests/ser.rs
@@ -3,6 +3,7 @@ use serde::Serialize;
 use serde_json::json;
 use serde_v8::utils::js_exec;
 use serde_v8::utils::v8_do;
+use serde_v8::BigInt;
 
 #[derive(Debug, Serialize, PartialEq)]
 struct MathOp {
@@ -138,6 +139,61 @@ sertest!(
 );
 
 sertest!(
+  ser_bigint_u8,
+  BigInt::from(num_bigint::BigInt::from(255_u8)),
+  "x === 255n"
+);
+sertest!(
+  ser_bigint_i8,
+  BigInt::from(num_bigint::BigInt::from(-128_i8)),
+  "x === -128n"
+);
+sertest!(
+  ser_bigint_u16,
+  BigInt::from(num_bigint::BigInt::from(65535_u16)),
+  "x === 65535n"
+);
+sertest!(
+  ser_bigint_i16,
+  BigInt::from(num_bigint::BigInt::from(-32768_i16)),
+  "x === -32768n"
+);
+sertest!(
+  ser_bigint_u32,
+  BigInt::from(num_bigint::BigInt::from(4294967295_u32)),
+  "x === 4294967295n"
+);
+sertest!(
+  ser_bigint_i32,
+  BigInt::from(num_bigint::BigInt::from(-2147483648_i32)),
+  "x === -2147483648n"
+);
+sertest!(
+  ser_bigint_u64,
+  BigInt::from(num_bigint::BigInt::from(9007199254740991_u64)),
+  "x === 9007199254740991n"
+);
+sertest!(
+  ser_bigint_i64,
+  BigInt::from(num_bigint::BigInt::from(-9007199254740991_i64)),
+  "x === -9007199254740991n"
+);
+sertest!(
+  ser_bigint_u128,
+  BigInt::from(num_bigint::BigInt::from(
+    340282366920938463463374607431768211455_u128
+  )),
+  "x === 340282366920938463463374607431768211455n"
+);
+sertest!(
+  ser_bigint_i128,
+  BigInt::from(num_bigint::BigInt::from(
+    -170141183460469231731687303715884105728_i128
+  )),
+  "x === -170141183460469231731687303715884105728n"
+);
+
+sertest!(
   ser_map,
   {
     let map: std::collections::BTreeMap<&str, u32> =