Bug 965830 - Add HandleValueArray class to receive rooted arrays of Values r=terrence

js/src/jsapi.cpp

@@ -115,6 +115,8 @@ using js::frontend::Parser;
 JS_STATIC_ASSERT((jschar)-1 > 0);
 JS_STATIC_ASSERT(sizeof(jschar) == 2);
 
+const JS::HandleValueArray JS::EmptyValueArray;
+
 JS_PUBLIC_API(int64_t)
 JS_Now()
 {

js/src/jsapi.h

@@ -600,6 +600,48 @@ class JS_PUBLIC_API(CustomAutoRooter) : private AutoGCRooter
     MOZ_DECL_USE_GUARD_OBJECT_NOTIFIER
 };
 
+/* A handle to an array of rooted values. */
+class HandleValueArray
+{
+    const size_t length_;
+    const Value *elements_;
+
+    HandleValueArray(size_t len, const Value *elements) : length_(len), elements_(elements) {}
+
+  public:
+    HandleValueArray() : length_(0), elements_(nullptr) {}
+    HandleValueArray(const RootedValue& value) : length_(1), elements_(value.address()) {}
+
+    HandleValueArray(const AutoValueVector& values)
+      : length_(values.length()), elements_(values.begin()) {}
+
+    template <size_t N>
+    HandleValueArray(const AutoValueArray<N>& values) : length_(N), elements_(values.begin()) {}
+
+    /* CallArgs must already be rooted somewhere up the stack. */
+    HandleValueArray(const JS::CallArgs& args) : length_(args.length()), elements_(args.array()) {}
+
+    /* Use with care! Only call this if the data is guaranteed to be marked. */
+    static HandleValueArray fromMarkedLocation(size_t len, const Value *elements) {
+        return HandleValueArray(len, elements);
+    }
+
+    static HandleValueArray subarray(const AutoValueVector& values, size_t startIndex, size_t len) {
+        JS_ASSERT(startIndex + len <= values.length());
+        return HandleValueArray(len, values.begin() + startIndex);
+    }
+
+    size_t length() const { return length_; }
+    const Value *begin() const { return elements_; }
+
+    HandleValue operator[](size_t i) const {
+        JS_ASSERT(i < length_);
+        return HandleValue::fromMarkedLocation(&elements_[i]);
+    }
+};
+
+extern JS_PUBLIC_DATA(const HandleValueArray) EmptyValueArray;
+
 }  /* namespace JS */
 
 /************************************************************************/