Auto merge of #340 - bd339:iss331, r=jdm

ArrayBufferView convenience method for typed arrays

Fixes #331 .

<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/rust-mozjs/340)
<!-- Reviewable:end -->

Author: bors-servo

src/typedarray.rs

@@ -21,6 +21,7 @@ use jsapi::HandleObject;
 use jsapi::JSContext;
 use jsapi::JSObject;
 use jsapi::JS_GetArrayBufferData;
+use jsapi::JS_GetArrayBufferViewType;
 use jsapi::JS_GetFloat32ArrayData;
 use jsapi::JS_GetFloat64ArrayData;
 use jsapi::JS_GetInt16ArrayData;
@@ -42,6 +43,7 @@ use jsapi::JS_NewUint8Array;
 use jsapi::JS_NewUint8ClampedArray;
 use jsapi::MutableHandleObject;
 use jsapi::Rooted;
+use jsapi::Type;
 use jsapi::UnwrapArrayBuffer;
 use jsapi::UnwrapArrayBufferView;
 use jsapi::UnwrapFloat32Array;
@@ -317,6 +319,12 @@ pub type ArrayBuffer<'a> = TypedArray<'a, ArrayBufferU8>;
 /// The ArrayBufferView type
 pub type ArrayBufferView<'a> = TypedArray<'a, ArrayBufferViewU8>;
 
+impl<'a> ArrayBufferView<'a> {
+    pub fn get_array_type(&self) -> Type {
+        unsafe { JS_GetArrayBufferViewType(self.object.get()) }
+    }
+}
+
 #[macro_export]
 macro_rules! typedarray {
     (in($cx:expr) let $name:ident : $ty:ident = $init:expr) => {

tests/typedarray.rs

@@ -9,6 +9,7 @@ use js::jsapi::CompartmentOptions;
 use js::jsapi::JSAutoCompartment;
 use js::jsapi::JS_NewGlobalObject;
 use js::jsapi::OnNewGlobalHookOption;
+use js::jsapi::Type;
 use js::jsval::UndefinedValue;
 use js::rust::Runtime as Runtime_;
 use js::rust::SIMPLE_GLOBAL_CLASS;
@@ -40,6 +41,9 @@ fn typedarray() {
         typedarray!(in(cx) let array: Uint16Array = rval.to_object());
         assert!(array.is_err());
 
+        typedarray!(in(cx) let view: ArrayBufferView = rval.to_object());
+        assert_eq!(view.unwrap().get_array_type(), Type::Uint8);
+
         rooted!(in(cx) let mut rval = ptr::null_mut());
         assert!(Uint32Array::create(cx, CreateWith::Slice(&[1, 3, 5]), rval.handle_mut()).is_ok());
 
@@ -63,6 +67,9 @@ fn typedarray() {
         typedarray!(in(cx) let mut array: Uint32Array = rval.get());
         array.as_mut().unwrap().update(&[0, 1, 2, 3]);
         assert_eq!(array.unwrap().as_slice(), &[0, 1, 2, 3, 0]);
+
+        typedarray!(in(cx) let view: ArrayBufferView = rval.get());
+        assert_eq!(view.unwrap().get_array_type(), Type::Uint32);
     }
 }