From 911a0c139d6862b2042b80439e958e2d0a9257fc Mon Sep 17 00:00:00 2001
From: LongYinan <lynweklm@gmail.com>
Date: Tue, 5 Jan 2021 23:27:01 +0800
Subject: [PATCH] feat(napi): Env::create_arraybuffer_with_borrowed_data

---
 napi/src/env.rs                   | 47 +++++++++++++++++++++++++++++--
 napi/src/js_values/arraybuffer.rs | 36 +++++++++++++++++------
 napi/src/js_values/mod.rs         |  3 +-
 3 files changed, 73 insertions(+), 13 deletions(-)

diff --git a/napi/src/env.rs b/napi/src/env.rs
index 73a294d2..e5894997 100644
--- a/napi/src/env.rs
+++ b/napi/src/env.rs
@@ -410,7 +410,7 @@ impl Env {
 
     Ok(JsArrayBufferValue::new(
       unsafe { JsArrayBuffer::from_raw_unchecked(self.0, raw_value) },
-      data,
+      mem::ManuallyDrop::new(data),
     ))
   }
 
@@ -436,7 +436,50 @@ impl Env {
         value: raw_value,
         value_type: ValueType::Object,
       }),
-      data,
+      mem::ManuallyDrop::new(data),
+    ))
+  }
+
+  #[inline]
+  /// # Safety
+  /// Mostly the same with `create_arraybuffer_with_data`
+  ///
+  /// Provided `finalize_callback` will be called when `Buffer` got dropped.
+  ///
+  /// You can pass in `noop_finalize` if you have nothing to do in finalize phase.
+  pub unsafe fn create_arraybuffer_with_borrowed_data<Hint, Finalize>(
+    &self,
+    data: *const u8,
+    length: usize,
+    hint: Hint,
+    finalize_callback: Finalize,
+  ) -> Result<JsArrayBufferValue>
+  where
+    Finalize: FnOnce(Hint, Env),
+  {
+    let mut raw_value = ptr::null_mut();
+    check_status!(sys::napi_create_external_arraybuffer(
+      self.0,
+      data as *mut c_void,
+      length,
+      Some(
+        raw_finalize_with_custom_callback::<Hint, Finalize>
+          as unsafe extern "C" fn(
+            env: sys::napi_env,
+            finalize_data: *mut c_void,
+            finalize_hint: *mut c_void,
+          )
+      ),
+      Box::into_raw(Box::new((hint, finalize_callback))) as *mut c_void,
+      &mut raw_value,
+    ))?;
+    Ok(JsArrayBufferValue::new(
+      JsArrayBuffer(Value {
+        env: self.0,
+        value: raw_value,
+        value_type: ValueType::Object,
+      }),
+      mem::ManuallyDrop::new(Vec::from_raw_parts(data as *mut u8, length, length)),
     ))
   }
 
diff --git a/napi/src/js_values/arraybuffer.rs b/napi/src/js_values/arraybuffer.rs
index e0c89f70..4a8dd8d4 100644
--- a/napi/src/js_values/arraybuffer.rs
+++ b/napi/src/js_values/arraybuffer.rs
@@ -2,10 +2,10 @@ use std::mem;
 use std::ops::{Deref, DerefMut};
 use std::os::raw::c_void;
 use std::ptr;
+use std::slice;
 
 use super::{Value, ValueType};
-use crate::check_status;
-use crate::{sys, JsUnknown, NapiValue, Ref, Result};
+use crate::{check_status, sys, JsUnknown, NapiValue, Ref, Result};
 
 pub struct JsArrayBuffer(pub(crate) Value);
 
@@ -18,7 +18,7 @@ pub struct JsTypedArray(pub(crate) Value);
 
 pub struct JsTypedArrayValue {
   pub arraybuffer: JsArrayBuffer,
-  _data: *mut c_void,
+  data: *mut c_void,
   pub byte_offset: u64,
   pub length: u64,
   pub typedarray_type: TypedArrayType,
@@ -164,11 +164,8 @@ impl JsArrayBuffer {
 
 impl JsArrayBufferValue {
   #[inline]
-  pub fn new(value: JsArrayBuffer, data: Vec<u8>) -> Self {
-    JsArrayBufferValue {
-      value,
-      data: mem::ManuallyDrop::new(data),
-    }
+  pub fn new(value: JsArrayBuffer, data: mem::ManuallyDrop<Vec<u8>>) -> Self {
+    JsArrayBufferValue { value, data }
   }
 
   #[inline]
@@ -227,7 +224,7 @@ impl JsTypedArray {
     })?;
 
     Ok(JsTypedArrayValue {
-      _data: data,
+      data,
       length: len,
       byte_offset,
       typedarray_type: typedarray_type.into(),
@@ -236,6 +233,27 @@ impl JsTypedArray {
   }
 }
 
+impl JsTypedArrayValue {
+  #[inline(always)]
+  fn as_slice(&self) -> &[u8] {
+    unsafe { slice::from_raw_parts(self.data as *const u8, self.length as usize) }
+  }
+}
+
+impl AsRef<[u8]> for JsTypedArrayValue {
+  fn as_ref(&self) -> &[u8] {
+    self.as_slice()
+  }
+}
+
+impl Deref for JsTypedArrayValue {
+  type Target = [u8];
+
+  fn deref(&self) -> &[u8] {
+    self.as_slice()
+  }
+}
+
 impl JsDataView {
   #[inline]
   pub fn into_value(self) -> Result<JsDataViewValue> {
diff --git a/napi/src/js_values/mod.rs b/napi/src/js_values/mod.rs
index 99b4f99b..62040ae7 100644
--- a/napi/src/js_values/mod.rs
+++ b/napi/src/js_values/mod.rs
@@ -2,8 +2,7 @@ use std::convert::TryFrom;
 use std::ffi::CString;
 use std::ptr;
 
-use crate::check_status;
-use crate::{sys, Callback, Error, Result, Status};
+use crate::{check_status, sys, Callback, Error, Result, Status};
 
 #[cfg(feature = "serde-json")]
 mod de;