feat(serde_v8): DetachedBuffer (#14102)

1 files changed, 69 insertions, 0 deletions

diff --git a/serde_v8/magic/detached_buffer.rs b/serde_v8/magic/detached_buffer.rs
new file mode 100644
index 000000000..1435a0fa6
--- /dev/null
+++ b/serde_v8/magic/detached_buffer.rs
@@ -0,0 +1,69 @@
+// Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.
+
+use core::ops::Range;
+use std::ops::Deref;
+use std::ops::DerefMut;
+
+use super::transl8::FromV8;
+use super::transl8::ToV8;
+use super::zero_copy_buf::to_ranged_buffer;
+use super::zero_copy_buf::ZeroCopyBuf;
+use crate::magic::transl8::impl_magic;
+
+// A buffer that detaches when deserialized from JS
+pub struct DetachedBuffer(ZeroCopyBuf);
+impl_magic!(DetachedBuffer);
+
+impl AsRef<[u8]> for DetachedBuffer {
+  fn as_ref(&self) -> &[u8] {
+    self.0.as_ref()
+  }
+}
+
+impl AsMut<[u8]> for DetachedBuffer {
+  fn as_mut(&mut self) -> &mut [u8] {
+    self.0.as_mut()
+  }
+}
+
+impl Deref for DetachedBuffer {
+  type Target = [u8];
+  fn deref(&self) -> &[u8] {
+    self.0.deref()
+  }
+}
+
+impl DerefMut for DetachedBuffer {
+  fn deref_mut(&mut self) -> &mut [u8] {
+    self.0.deref_mut()
+  }
+}
+
+impl ToV8 for DetachedBuffer {
+  fn to_v8<'a>(
+    &self,
+    scope: &mut v8::HandleScope<'a>,
+  ) -> Result<v8::Local<'a, v8::Value>, crate::Error> {
+    let buffer = v8::ArrayBuffer::with_backing_store(scope, &self.0.store);
+    let Range { start, end } = self.0.range;
+    let (off, len) = (start, end - start);
+    let v = v8::Uint8Array::new(scope, buffer, off, len).unwrap();
+    Ok(v.into())
+  }
+}
+
+impl FromV8 for DetachedBuffer {
+  fn from_v8(
+    scope: &mut v8::HandleScope,
+    value: v8::Local<v8::Value>,
+  ) -> Result<Self, crate::Error> {
+    let (b, range) =
+      to_ranged_buffer(scope, value).or(Err(crate::Error::ExpectedBuffer))?;
+    if !b.is_detachable() {
+      return Err(crate::Error::ExpectedDetachable);
+    }
+    let store = b.get_backing_store();
+    b.detach(); // Detach
+    Ok(Self(ZeroCopyBuf { store, range }))
+  }
+}