gecko-dev/dom/bindings/ToJSValue.h
Kyle Huey 91315e3b5f Bug 1031051: Part 13 - Support ToJSValue()ing CallbackObjects and nsTArrays of raw pointers. r=bz
Without special handling CallbackObject subclasses will fall into the "nsISupports but not nsWrapperCache" case which goes through an XPConnect wrapping path that has no idea how to cope with a CallbackObject.  We need both the CallbackObject overload and the EnableIf bit in the template because the template will bind to the subclass and thus be preferred to the CallbackObject overload which requires an implicit conversion to the base class.

Before this patch nsTArray<T*> will eventually try to ToJSValue a T* which will select the boolean overload.  Thanks C++!  The new template overload that takes a T and attempts to dereference it will be preferred because it can bind to the type directly and does not require the implicit (and terrible!) conversion to bool.  This template is written in terms of T and not T* so we can test to see if T is a pointer type (and not merely something that can be coerced to a T*, such as a T[N]).
2014-06-30 16:02:03 -07:00

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/* -*- 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_ToJSValue_h
#define mozilla_dom_ToJSValue_h
#include "mozilla/TypeTraits.h"
#include "mozilla/Assertions.h"
#include "mozilla/dom/BindingUtils.h"
#include "mozilla/dom/TypedArray.h"
#include "jsapi.h"
#include "nsISupports.h"
#include "nsTArray.h"
#include "nsWrapperCache.h"
namespace mozilla {
namespace dom {
// If ToJSValue returns false, it must set an exception on the
// JSContext.
// Accept strings.
bool
ToJSValue(JSContext* aCx,
const nsAString& aArgument,
JS::MutableHandle<JS::Value> aValue);
// Accept booleans.
inline bool
ToJSValue(JSContext* aCx,
bool aArgument,
JS::MutableHandle<JS::Value> aValue)
{
// Make sure we're called in a compartment
MOZ_ASSERT(JS::CurrentGlobalOrNull(aCx));
aValue.setBoolean(aArgument);
return true;
}
// Accept integer types
inline bool
ToJSValue(JSContext* aCx,
int32_t aArgument,
JS::MutableHandle<JS::Value> aValue)
{
// Make sure we're called in a compartment
MOZ_ASSERT(JS::CurrentGlobalOrNull(aCx));
aValue.setInt32(aArgument);
return true;
}
// The uint32_t version is disabled for now because on the super-old b2g
// compiler nsresult and uint32_t are the same type. If someone needs this at
// some point we'll need to figure out how to make it work (e.g. by switching to
// traits structs and using the trick IPC's ParamTraits uses, where a traits
// struct templated on the type inherits from a base traits struct of some sort,
// templated on the same type, or something). Maybe b2g will update to a modern
// compiler before that happens....
#if 0
inline bool
ToJSValue(JSContext* aCx,
uint32_t aArgument,
JS::MutableHandle<JS::Value> aValue)
{
// Make sure we're called in a compartment
MOZ_ASSERT(JS::CurrentGlobalOrNull(aCx));
aValue.setNumber(aArgument);
return true;
}
#endif
inline bool
ToJSValue(JSContext* aCx,
int64_t aArgument,
JS::MutableHandle<JS::Value> aValue)
{
// Make sure we're called in a compartment
MOZ_ASSERT(JS::CurrentGlobalOrNull(aCx));
aValue.setNumber(double(aArgument));
return true;
}
inline bool
ToJSValue(JSContext* aCx,
uint64_t aArgument,
JS::MutableHandle<JS::Value> aValue)
{
// Make sure we're called in a compartment
MOZ_ASSERT(JS::CurrentGlobalOrNull(aCx));
aValue.setNumber(double(aArgument));
return true;
}
// accept floating point types
inline bool
ToJSValue(JSContext* aCx,
float aArgument,
JS::MutableHandle<JS::Value> aValue)
{
// Make sure we're called in a compartment
MOZ_ASSERT(JS::CurrentGlobalOrNull(aCx));
aValue.setNumber(aArgument);
return true;
}
inline bool
ToJSValue(JSContext* aCx,
double aArgument,
JS::MutableHandle<JS::Value> aValue)
{
// Make sure we're called in a compartment
MOZ_ASSERT(JS::CurrentGlobalOrNull(aCx));
aValue.setNumber(aArgument);
return true;
}
// Accept CallbackObjects
inline bool
ToJSValue(JSContext* aCx,
CallbackObject& aArgument,
JS::MutableHandle<JS::Value> aValue)
{
// Make sure we're called in a compartment
MOZ_ASSERT(JS::CurrentGlobalOrNull(aCx));
aValue.setObject(*aArgument.Callback());
return MaybeWrapValue(aCx, aValue);
}
// Accept objects that inherit from nsWrapperCache and nsISupports (e.g. most
// DOM objects).
template <class T>
typename EnableIf<IsBaseOf<nsWrapperCache, T>::value &&
IsBaseOf<nsISupports, T>::value, bool>::Type
ToJSValue(JSContext* aCx,
T& aArgument,
JS::MutableHandle<JS::Value> aValue)
{
// Make sure we're called in a compartment
MOZ_ASSERT(JS::CurrentGlobalOrNull(aCx));
// Make sure non-webidl objects don't sneak in here
MOZ_ASSERT(aArgument.IsDOMBinding());
return WrapNewBindingObject(aCx, aArgument, aValue);
}
// Accept typed arrays built from appropriate nsTArray values
template<typename T>
typename EnableIf<IsBaseOf<AllTypedArraysBase, T>::value, bool>::Type
ToJSValue(JSContext* aCx,
const TypedArrayCreator<T>& aArgument,
JS::MutableHandle<JS::Value> aValue)
{
// Make sure we're called in a compartment
MOZ_ASSERT(JS::CurrentGlobalOrNull(aCx));
JSObject* obj = aArgument.Create(aCx);
if (!obj) {
return false;
}
aValue.setObject(*obj);
return true;
}
// We don't want to include nsContentUtils here, so use a helper
// function for the nsISupports case.
namespace tojsvalue_detail {
bool
ISupportsToJSValue(JSContext* aCx,
nsISupports* aArgument,
JS::MutableHandle<JS::Value> aValue);
} // namespace tojsvalue_detail
// Accept objects that inherit from nsISupports but not nsWrapperCache (e.g.
// nsIDOMFile).
template <class T>
typename EnableIf<!IsBaseOf<nsWrapperCache, T>::value &&
!IsBaseOf<CallbackObject, T>::value &&
IsBaseOf<nsISupports, T>::value, bool>::Type
ToJSValue(JSContext* aCx,
T& aArgument,
JS::MutableHandle<JS::Value> aValue)
{
// Make sure we're called in a compartment
MOZ_ASSERT(JS::CurrentGlobalOrNull(aCx));
return tojsvalue_detail::ISupportsToJSValue(aCx, &aArgument, aValue);
}
// Accept nsRefPtr/nsCOMPtr
template <typename T>
bool
ToJSValue(JSContext* aCx,
const nsCOMPtr<T>& aArgument,
JS::MutableHandle<JS::Value> aValue)
{
return ToJSValue(aCx, *aArgument.get(), aValue);
}
template <typename T>
bool
ToJSValue(JSContext* aCx,
const nsRefPtr<T>& aArgument,
JS::MutableHandle<JS::Value> aValue)
{
return ToJSValue(aCx, *aArgument.get(), aValue);
}
// Accept WebIDL dictionaries
template <class T>
typename EnableIf<IsBaseOf<DictionaryBase, T>::value, bool>::Type
ToJSValue(JSContext* aCx,
const T& aArgument,
JS::MutableHandle<JS::Value> aValue)
{
return aArgument.ToObjectInternal(aCx, aValue);
}
// Accept existing JS values (which may not be same-compartment with us
inline bool
ToJSValue(JSContext* aCx, JS::Handle<JS::Value> aArgument,
JS::MutableHandle<JS::Value> aValue)
{
aValue.set(aArgument);
return MaybeWrapValue(aCx, aValue);
}
// Accept nsresult, for use in rejections, and create an XPCOM
// exception object representing that nsresult.
bool
ToJSValue(JSContext* aCx,
nsresult aArgument,
JS::MutableHandle<JS::Value> aValue);
// Accept pointers to other things we accept
template <typename T>
typename EnableIf<IsPointer<T>::value, bool>::Type
ToJSValue(JSContext* aCx,
T aArgument,
JS::MutableHandle<JS::Value> aValue)
{
return ToJSValue(aCx, *aArgument, aValue);
}
// Accept arrays of other things we accept
template <typename T>
bool
ToJSValue(JSContext* aCx,
T* aArguments,
size_t aLength,
JS::MutableHandle<JS::Value> aValue)
{
// Make sure we're called in a compartment
MOZ_ASSERT(JS::CurrentGlobalOrNull(aCx));
JS::AutoValueVector v(aCx);
if (!v.resize(aLength)) {
return false;
}
for (size_t i = 0; i < aLength; ++i) {
if (!ToJSValue(aCx, aArguments[i], v[i])) {
return false;
}
}
JSObject* arrayObj = JS_NewArrayObject(aCx, v);
if (!arrayObj) {
return false;
}
aValue.setObject(*arrayObj);
return true;
}
template <typename T>
bool
ToJSValue(JSContext* aCx,
const nsTArray<T>& aArgument,
JS::MutableHandle<JS::Value> aValue)
{
return ToJSValue(aCx, aArgument.Elements(),
aArgument.Length(), aValue);
}
template <typename T>
bool
ToJSValue(JSContext* aCx,
const FallibleTArray<T>& aArgument,
JS::MutableHandle<JS::Value> aValue)
{
return ToJSValue(aCx, aArgument.Elements(),
aArgument.Length(), aValue);
}
template <typename T, int N>
bool
ToJSValue(JSContext* aCx,
const T(&aArgument)[N],
JS::MutableHandle<JS::Value> aValue)
{
return ToJSValue(aCx, aArgument, N, aValue);
}
} // namespace dom
} // namespace mozilla
#endif /* mozilla_dom_ToJSValue_h */