Bug 747827. Add some structs that can be used to represent typed arrays in DOM bindings. r=peterv

dom/bindings/Makefile.in

@@ -52,6 +52,7 @@ EXPORTS_$(binding_include_path) = \
   PrototypeList.h \
   RegisterBindings.h \
   Nullable.h \
+  TypedArray.h \
   BindingUtils.h \
   $(binding_header_files) \
   $(NULL)

dom/bindings/TypedArray.h

@@ -0,0 +1,97 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-*/
+/* vim: set ts=2 sw=2 et tw=79: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_TypedArray_h
+#define mozilla_dom_TypedArray_h
+
+#include "jsfriendapi.h"
+
+namespace mozilla {
+namespace dom {
+
+/*
+ * Various typed array classes for argument conversion.  We have a base class
+ * that has a way of initializing a TypedArray from an existing typed array, and
+ * a subclass of the base class that supports creation of a relevant typed array
+ * or array buffer object.
+ */
+template<typename T, typename U,
+         U* GetData(JSObject*, JSContext*),
+         uint32_t GetLength(JSObject*, JSContext*)>
+struct TypedArray_base {
+  TypedArray_base(JSContext* cx, JSObject* obj) :
+    mData(static_cast<T*>(GetData(obj, cx))),
+    mLength(GetLength(obj, cx)),
+    mObj(obj)
+  {}
+
+  T* const mData;
+  const uint32_t mLength;
+  JSObject* const mObj;
+};
+
+
+template<typename T, typename U,
+         U* GetData(JSObject*, JSContext*),
+         uint32_t GetLength(JSObject*, JSContext*),
+         JSObject* CreateNew(JSContext*, uint32_t)>
+struct TypedArray : public TypedArray_base<T,U,GetData,GetLength> {
+  TypedArray(JSContext* cx, JSObject* obj) :
+    TypedArray_base<T,U,GetData,GetLength>(cx, obj)
+  {}
+  
+  static inline JSObject*
+  Create(JSContext* cx, uint32_t length, T* data = NULL) {
+    JSObject* obj = CreateNew(cx, length);
+    if (!obj) {
+      return NULL;
+    }
+    if (data) {
+      T* buf = static_cast<T*>(GetData(obj, cx));
+      memcpy(buf, data, length*sizeof(T));
+    }
+    return obj;
+  }
+};
+
+typedef TypedArray<int8_t, int8_t, JS_GetInt8ArrayData, JS_GetTypedArrayLength,
+                   JS_NewInt8Array>
+        Int8Array;
+typedef TypedArray<uint8_t, uint8_t, JS_GetUint8ArrayData,
+                   JS_GetTypedArrayLength, JS_NewUint8Array>
+        Uint8Array;
+typedef TypedArray<uint8_t, uint8_t, JS_GetUint8ClampedArrayData,
+                   JS_GetTypedArrayLength, JS_NewUint8Array>
+        Uint8ClampedArray;
+typedef TypedArray<int16_t, int16_t, JS_GetInt16ArrayData,
+                   JS_GetTypedArrayLength, JS_NewInt16Array>
+        Int16Array;
+typedef TypedArray<uint16_t, uint16_t, JS_GetUint16ArrayData,
+                   JS_GetTypedArrayLength, JS_NewUint16Array>
+        Uint16Array;
+typedef TypedArray<int32_t, int32_t, JS_GetInt32ArrayData,
+                   JS_GetTypedArrayLength, JS_NewInt32Array>
+        Int32Array;
+typedef TypedArray<uint32_t, uint32_t, JS_GetUint32ArrayData,
+                   JS_GetTypedArrayLength, JS_NewUint32Array>
+        Uint32Array;
+typedef TypedArray<float, float, JS_GetFloat32ArrayData, JS_GetTypedArrayLength,
+                   JS_NewFloat32Array>
+        Float32Array;
+typedef TypedArray<double, double, JS_GetFloat64ArrayData,
+                   JS_GetTypedArrayLength, JS_NewFloat64Array>
+        Float64Array;
+typedef TypedArray_base<uint8_t, void, JS_GetArrayBufferViewData,
+                        JS_GetArrayBufferViewByteLength>
+        ArrayBufferView;
+typedef TypedArray<uint8_t, uint8_t, JS_GetArrayBufferData,
+                   JS_GetArrayBufferByteLength, JS_NewArrayBuffer>
+        ArrayBuffer;
+
+} // namespace dom
+} // namespace mozilla
+
+#endif /* mozilla_dom_TypedArray_h */