Add jsg::JsUint8Array utility

Author: jasnell

src/workerd/jsg/jsg.h

@@ -2235,7 +2235,8 @@ class JsMessage;
   V(Set)                                                                                           \
   V(Promise)                                                                                       \
   V(Proxy)                                                                                         \
-  V(Function)
+  V(Function)                                                                                      \
+  V(Uint8Array)
 
 #define V(Name) class Js##Name;
 JS_TYPE_CLASSES(V)

src/workerd/jsg/jsvalue.h

@@ -44,7 +44,6 @@ inline void requireOnStack(void* self) {
   V(ArrayBuffer)                                                                                   \
   V(ArrayBufferView)                                                                               \
   V(TypedArray)                                                                                    \
-  V(Uint8Array)                                                                                    \
   V(Uint8ClampedArray)                                                                             \
   V(Int8Array)                                                                                     \
   V(Uint16Array)                                                                                   \
@@ -230,6 +229,20 @@ class JsArray final: public JsBase<v8::Array, JsArray> {
   using JsBase<v8::Array, JsArray>::JsBase;
 };
 
+class JsUint8Array final: public JsBase<v8::Uint8Array, JsUint8Array> {
+ public:
+  template <typename T = kj::byte>
+  kj::ArrayPtr<T> asArrayPtr() {
+    v8::Local<v8::Uint8Array> inner = *this;
+    auto buf = inner->Buffer();
+    T* data = static_cast<T*>(buf->Data()) + inner->ByteOffset();
+    size_t length = inner->ByteLength();
+    return kj::ArrayPtr(data, length);
+  }
+
+  using JsBase<v8::Uint8Array, JsUint8Array>::JsBase;
+};
+
 class JsString final: public JsBase<v8::String, JsString> {
  public:
   int length(Lock& js) const KJ_WARN_UNUSED_RESULT;

src/workerd/jsg/rtti.h

@@ -468,6 +468,7 @@ struct BuildRtti<Configuration, v8::Promise> {
   };
 
 #define FOR_EACH_BUILTIN_TYPE(F, ...)                                                              \
+  F(jsg::JsUint8Array, BuiltinType::Type::V8_UINT8_ARRAY)                                          \
   F(jsg::BufferSource, BuiltinType::Type::JSG_BUFFER_SOURCE)                                       \
   F(kj::Date, BuiltinType::Type::KJ_DATE)                                                          \
   F(v8::ArrayBufferView, BuiltinType::Type::V8_ARRAY_BUFFER_VIEW)                                  \