refactor(serde_v8): split ZeroCopyBuf into JsBuffer and ToJsBuffer (#19566)

`ZeroCopyBuf` was convenient to use, but sometimes it did hide details
that some copies were necessary in certain cases. Also it made it way to easy
for the caller to pass around and convert into different values. This commit
splits `ZeroCopyBuf` into `JsBuffer` (an array buffer coming from V8) and
`ToJsBuffer` (a Rust buffer that will be converted into a V8 array buffer).

As a result some magical conversions were removed (they were never used)
limiting the API surface and preparing for changes in #19534.

1 files changed, 7 insertions, 17 deletions

diff --git a/serde_v8/ser.rs b/serde_v8/ser.rs
index 74ad9ec10..51625f230 100644
--- a/serde_v8/ser.rs
+++ b/serde_v8/ser.rs
@@ -19,9 +19,8 @@ use crate::BigInt;
 use crate::ByteString;
 use crate::DetachedBuffer;
 use crate::ExternalPointer;
-use crate::StringOrBuffer;
+use crate::ToJsBuffer;
 use crate::U16String;
-use crate::ZeroCopyBuf;
 
 type JsValue<'s> = v8::Local<'s, v8::Value>;
 type JsResult<'s> = Result<JsValue<'s>>;
@@ -274,12 +273,11 @@ impl<'a, 'b, 'c, T: MagicType + ToV8> ser::SerializeStruct
 pub enum StructSerializers<'a, 'b, 'c> {
   ExternalPointer(MagicalSerializer<'a, 'b, 'c, magic::ExternalPointer>),
   Magic(MagicalSerializer<'a, 'b, 'c, magic::Value<'a>>),
-  ZeroCopyBuf(MagicalSerializer<'a, 'b, 'c, ZeroCopyBuf>),
+  RustToV8Buf(MagicalSerializer<'a, 'b, 'c, ToJsBuffer>),
   MagicAnyValue(MagicalSerializer<'a, 'b, 'c, AnyValue>),
   MagicDetached(MagicalSerializer<'a, 'b, 'c, DetachedBuffer>),
   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>),
 }
@@ -296,14 +294,11 @@ impl<'a, 'b, 'c> ser::SerializeStruct for StructSerializers<'a, 'b, 'c> {
     match self {
       StructSerializers::ExternalPointer(s) => s.serialize_field(key, value),
       StructSerializers::Magic(s) => s.serialize_field(key, value),
-      StructSerializers::ZeroCopyBuf(s) => s.serialize_field(key, value),
+      StructSerializers::RustToV8Buf(s) => s.serialize_field(key, value),
       StructSerializers::MagicAnyValue(s) => s.serialize_field(key, value),
       StructSerializers::MagicDetached(s) => s.serialize_field(key, value),
       StructSerializers::MagicByteString(s) => s.serialize_field(key, value),
       StructSerializers::MagicU16String(s) => s.serialize_field(key, value),
-      StructSerializers::MagicStringOrBuffer(s) => {
-        s.serialize_field(key, value)
-      }
       StructSerializers::MagicBigInt(s) => s.serialize_field(key, value),
       StructSerializers::Regular(s) => s.serialize_field(key, value),
     }
@@ -313,12 +308,11 @@ impl<'a, 'b, 'c> ser::SerializeStruct for StructSerializers<'a, 'b, 'c> {
     match self {
       StructSerializers::ExternalPointer(s) => s.end(),
       StructSerializers::Magic(s) => s.end(),
-      StructSerializers::ZeroCopyBuf(s) => s.end(),
+      StructSerializers::RustToV8Buf(s) => s.end(),
       StructSerializers::MagicAnyValue(s) => s.end(),
       StructSerializers::MagicDetached(s) => s.end(),
       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(),
     }
@@ -588,9 +582,9 @@ impl<'a, 'b, 'c> ser::Serializer for Serializer<'a, 'b, 'c> {
         let m = MagicalSerializer::<U16String>::new(self.scope);
         Ok(StructSerializers::MagicU16String(m))
       }
-      ZeroCopyBuf::MAGIC_NAME => {
-        let m = MagicalSerializer::<ZeroCopyBuf>::new(self.scope);
-        Ok(StructSerializers::ZeroCopyBuf(m))
+      ToJsBuffer::MAGIC_NAME => {
+        let m = MagicalSerializer::<ToJsBuffer>::new(self.scope);
+        Ok(StructSerializers::RustToV8Buf(m))
       }
       AnyValue::MAGIC_NAME => {
         let m = MagicalSerializer::<AnyValue>::new(self.scope);
@@ -600,10 +594,6 @@ impl<'a, 'b, 'c> ser::Serializer for Serializer<'a, 'b, 'c> {
         let m = MagicalSerializer::<DetachedBuffer>::new(self.scope);
         Ok(StructSerializers::MagicDetached(m))
       }
-      StringOrBuffer::MAGIC_NAME => {
-        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))