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.

2 files changed, 15 insertions, 18 deletions

diff --git a/serde_v8/tests/de.rs b/serde_v8/tests/de.rs
index 4c5cf7283..3abaa0979 100644
--- a/serde_v8/tests/de.rs
+++ b/serde_v8/tests/de.rs
@@ -7,8 +7,8 @@ use serde_v8::utils::v8_do;
 use serde_v8::BigInt;
 use serde_v8::ByteString;
 use serde_v8::Error;
+use serde_v8::JsBuffer;
 use serde_v8::U16String;
-use serde_v8::ZeroCopyBuf;
 
 #[derive(Debug, Deserialize, PartialEq)]
 struct MathOp {
@@ -248,31 +248,31 @@ fn de_string_or_buffer() {
 fn de_buffers() {
   // ArrayBufferView
   dedo("new Uint8Array([97])", |scope, v| {
-    let buf: ZeroCopyBuf = serde_v8::from_v8(scope, v).unwrap();
+    let buf: JsBuffer = serde_v8::from_v8(scope, v).unwrap();
     assert_eq!(&*buf, &[97]);
   });
 
   // ArrayBuffer
   dedo("(new Uint8Array([97])).buffer", |scope, v| {
-    let buf: ZeroCopyBuf = serde_v8::from_v8(scope, v).unwrap();
+    let buf: JsBuffer = serde_v8::from_v8(scope, v).unwrap();
     assert_eq!(&*buf, &[97]);
   });
 
   dedo(
     "(Uint8Array.from([0x68, 0x65, 0x6C, 0x6C, 0x6F]))",
     |scope, v| {
-      let buf: ZeroCopyBuf = serde_v8::from_v8(scope, v).unwrap();
+      let buf: JsBuffer = serde_v8::from_v8(scope, v).unwrap();
       assert_eq!(&*buf, &[0x68, 0x65, 0x6C, 0x6C, 0x6F]);
     },
   );
 
   dedo("(new ArrayBuffer(4))", |scope, v| {
-    let buf: ZeroCopyBuf = serde_v8::from_v8(scope, v).unwrap();
+    let buf: JsBuffer = serde_v8::from_v8(scope, v).unwrap();
     assert_eq!(&*buf, &[0x0, 0x0, 0x0, 0x0]);
   });
 
   dedo("(new ArrayBuffer(8, { maxByteLength: 16}))", |scope, v| {
-    let result: Result<ZeroCopyBuf, Error> = serde_v8::from_v8(scope, v);
+    let result: Result<JsBuffer, Error> = serde_v8::from_v8(scope, v);
     matches!(result, Err(Error::ResizableBackingStoreNotSupported));
   });
 }
diff --git a/serde_v8/tests/magic.rs b/serde_v8/tests/magic.rs
index 8ae163784..09e520561 100644
--- a/serde_v8/tests/magic.rs
+++ b/serde_v8/tests/magic.rs
@@ -68,27 +68,26 @@ fn magic_buffer() {
 
     // Simple buffer
     let v8_array = js_exec(scope, "new Uint8Array([1,2,3,4,5])");
-    let zbuf: serde_v8::ZeroCopyBuf =
-      serde_v8::from_v8(scope, v8_array).unwrap();
+    let zbuf: serde_v8::JsBuffer = serde_v8::from_v8(scope, v8_array).unwrap();
     assert_eq!(&*zbuf, &[1, 2, 3, 4, 5]);
 
     // Multi buffers
     let v8_arrays =
       js_exec(scope, "[new Uint8Array([1,2]), new Uint8Array([3,4,5])]");
-    let (z1, z2): (serde_v8::ZeroCopyBuf, serde_v8::ZeroCopyBuf) =
+    let (z1, z2): (serde_v8::JsBuffer, serde_v8::JsBuffer) =
       serde_v8::from_v8(scope, v8_arrays).unwrap();
     assert_eq!(&*z1, &[1, 2]);
     assert_eq!(&*z2, &[3, 4, 5]);
 
     // Wrapped in option, like our current op-ABI
     let v8_array = js_exec(scope, "new Uint8Array([1,2,3,4,5])");
-    let zbuf: Option<serde_v8::ZeroCopyBuf> =
+    let zbuf: Option<serde_v8::JsBuffer> =
       serde_v8::from_v8(scope, v8_array).unwrap();
     assert_eq!(&*zbuf.unwrap(), &[1, 2, 3, 4, 5]);
 
     // Observe mutation in JS
     let v8_array = js_exec(scope, "new Uint8Array([1,2,3,4,5])");
-    let mut zbuf: serde_v8::ZeroCopyBuf =
+    let mut zbuf: serde_v8::JsBuffer =
       serde_v8::from_v8(scope, v8_array).unwrap();
     let key = serde_v8::to_v8(scope, "t1").unwrap();
     global.set(scope, key, v8_array);
@@ -99,13 +98,12 @@ fn magic_buffer() {
     // Shared buffers
     let v8_array =
       js_exec(scope, "new Uint8Array(new SharedArrayBuffer([1,2,3,4,5]))");
-    let zbuf: Result<serde_v8::ZeroCopyBuf> =
-      serde_v8::from_v8(scope, v8_array);
+    let zbuf: Result<serde_v8::JsBuffer> = serde_v8::from_v8(scope, v8_array);
     assert!(zbuf.is_err());
 
     // Serialization
     let buf: Vec<u8> = vec![1, 2, 3, 99, 5];
-    let zbuf: serde_v8::ZeroCopyBuf = buf.into();
+    let zbuf: serde_v8::ToJsBuffer = buf.into();
     let v8_value = serde_v8::to_v8(scope, zbuf).unwrap();
     let key = serde_v8::to_v8(scope, "t2").unwrap();
     global.set(scope, key, v8_value);
@@ -115,8 +113,8 @@ fn magic_buffer() {
     // Composite Serialization
     #[derive(serde::Serialize)]
     struct Wrapper {
-      a: serde_v8::ZeroCopyBuf,
-      b: serde_v8::ZeroCopyBuf,
+      a: serde_v8::ToJsBuffer,
+      b: serde_v8::ToJsBuffer,
     }
     let buf1: Vec<u8> = vec![1, 2, 33, 4, 5];
     let buf2: Vec<u8> = vec![5, 4, 3, 2, 11];
@@ -134,8 +132,7 @@ fn magic_buffer() {
 
     // ZeroCopyBuf as bytes::Bytes
     let v8_array = js_exec(scope, "new Uint8Array([1,2,3,4,5])");
-    let zbuf: serde_v8::ZeroCopyBuf =
-      serde_v8::from_v8(scope, v8_array).unwrap();
+    let zbuf: serde_v8::JsBuffer = serde_v8::from_v8(scope, v8_array).unwrap();
     let buf: bytes::Bytes = zbuf.into();
     assert_eq!(buf, bytes::Bytes::from_static(&[1, 2, 3, 4, 5]));
     assert_eq!(buf, bytes::Bytes::from_static(&[1, 2, 3, 4, 5]));