feat: add get_backing_store to ArrayBufferView (#1342)

src/array_buffer_view.rs

@@ -4,8 +4,10 @@ use std::ffi::c_void;
 use crate::support::int;
 use crate::ArrayBuffer;
 use crate::ArrayBufferView;
+use crate::BackingStore;
 use crate::HandleScope;
 use crate::Local;
+use crate::SharedRef;
 
 extern "C" {
   fn v8__ArrayBufferView__Buffer(
@@ -33,6 +35,16 @@ impl ArrayBufferView {
     unsafe { scope.cast_local(|_| v8__ArrayBufferView__Buffer(self)) }
   }
 
+  /// Get a shared pointer to the backing store of this array buffer. This
+  /// pointer coordinates the lifetime management of the internal storage
+  /// with any live ArrayBuffers on the heap, even across isolates. The embedder
+  /// should not attempt to manage lifetime of the storage through other means.
+  #[inline(always)]
+  pub fn get_backing_store(&self) -> Option<SharedRef<BackingStore>> {
+    let buffer = unsafe { v8__ArrayBufferView__Buffer(self) };
+    unsafe { buffer.as_ref().map(|buffer| buffer.get_backing_store()) }
+  }
+
   /// Returns the underlying storage for this `ArrayBufferView`, including the built-in `byte_offset`.
   /// This is a more efficient way of calling `buffer(scope)->data()`, and may be called without a
   /// scope.

tests/test_api.rs

@@ -5094,6 +5094,10 @@ fn array_buffer_view() {
     assert!(maybe_ab.is_some());
     let ab = maybe_ab.unwrap();
     assert_eq!(ab.byte_length(), 6);
+    assert_eq!(
+      result.get_backing_store().unwrap().data(),
+      ab.get_backing_store().data()
+    );
   }
 }