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gecko-dev/dom/bindings/ToJSValue.h

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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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 <cstddef> // for size_t
#include <cstdint> // for int32_t, int64_t, uint32_t, uint64_t
#include <type_traits> // for is_base_of, enable_if_t, enable_if, is_pointer, is_same, void_t
#include <utility> // for forward
#include "ErrorList.h" // for nsresult
#include "js/Array.h" // for NewArrayObject
#include "js/GCVector.h" // for RootedVector, MutableWrappedPtrOperations
#include "js/RootingAPI.h" // for MutableHandle, Rooted, Handle, Heap
#include "js/Value.h" // for Value
#include "js/ValueArray.h" // for HandleValueArray
#include "jsapi.h" // for CurrentGlobalOrNull
#include "mozilla/Assertions.h" // for AssertionConditionType, MOZ_ASSERT, MOZ_ASSERT_HELPER1
#include "mozilla/UniquePtr.h" // for UniquePtr
#include "mozilla/Unused.h" // for Unused
#include "mozilla/dom/BindingUtils.h" // for MaybeWrapValue, MaybeWrapObjectOrNullValue, XPCOMObjectToJsval, GetOrCreateDOMReflector
#include "mozilla/dom/CallbackObject.h" // for CallbackObject
#include "mozilla/dom/Record.h"
#include "nsID.h" // for NS_GET_TEMPLATE_IID, nsIID
#include "nsISupports.h" // for nsISupports
#include "nsStringFwd.h" // for nsAString
#include "nsTArrayForwardDeclare.h"
#include "xpcObjectHelper.h" // for xpcObjectHelper
namespace mozilla {
namespace dom {
class CallbackObject;
class Promise;
class WindowProxyHolder;
template <typename TypedArrayType>
class TypedArrayCreator;
// If ToJSValue returns false, it must set an exception on the
// JSContext.
// Accept strings.
[[nodiscard]] bool ToJSValue(JSContext* aCx, const nsAString& aArgument,
JS::MutableHandle<JS::Value> aValue);
// Treats the input as UTF-8, and throws otherwise.
[[nodiscard]] bool ToJSValue(JSContext* aCx, const nsACString& aArgument,
JS::MutableHandle<JS::Value> aValue);
// Accept booleans. But be careful here: if we just have a function that takes
// a boolean argument, then any pointer that doesn't match one of our other
// signatures/templates will get treated as a boolean, which is clearly not
// desirable. So make this a template that only gets used if the argument type
// is actually boolean
template <typename T>
[[nodiscard]] std::enable_if_t<std::is_same<T, bool>::value, bool> ToJSValue(
JSContext* aCx, T 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;
}
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;
}
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
[[nodiscard]] 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.setObjectOrNull(aArgument.Callback(aCx));
return MaybeWrapValue(aCx, aValue);
}
// Accept objects that inherit from nsWrapperCache (e.g. most
// DOM objects).
template <class T>
[[nodiscard]] std::enable_if_t<std::is_base_of<nsWrapperCache, T>::value, bool>
ToJSValue(JSContext* aCx, T& aArgument, JS::MutableHandle<JS::Value> aValue) {
// Make sure we're called in a compartment
MOZ_ASSERT(JS::CurrentGlobalOrNull(aCx));
return GetOrCreateDOMReflector(aCx, aArgument, aValue);
}
// Accept non-refcounted DOM objects that do not inherit from
// nsWrapperCache. Refcounted ones would be too much of a footgun:
// you could convert them to JS twice and get two different objects.
namespace binding_detail {
template <class T>
[[nodiscard]] std::enable_if_t<
std::is_base_of<NonRefcountedDOMObject, T>::value, bool>
ToJSValueFromPointerHelper(JSContext* aCx, T* aArgument,
JS::MutableHandle<JS::Value> aValue) {
// Make sure we're called in a compartment
MOZ_ASSERT(JS::CurrentGlobalOrNull(aCx));
// This is a cut-down version of
// WrapNewBindingNonWrapperCachedObject that doesn't need to deal
// with nearly as many cases.
if (!aArgument) {
aValue.setNull();
return true;
}
JS::Rooted<JSObject*> obj(aCx);
if (!aArgument->WrapObject(aCx, nullptr, &obj)) {
return false;
}
aValue.setObject(*obj);
return true;
}
} // namespace binding_detail
// We can take a non-refcounted non-wrapper-cached DOM object that lives in a
// UniquePtr.
template <class T>
[[nodiscard]] std::enable_if_t<
std::is_base_of<NonRefcountedDOMObject, T>::value, bool>
ToJSValue(JSContext* aCx, UniquePtr<T>&& aArgument,
JS::MutableHandle<JS::Value> aValue) {
if (!binding_detail::ToJSValueFromPointerHelper(aCx, aArgument.get(),
aValue)) {
return false;
}
// JS object took ownership
Unused << aArgument.release();
return true;
}
// Accept typed arrays built from appropriate nsTArray values
template <typename T>
[[nodiscard]]
typename std::enable_if<std::is_base_of<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;
}
namespace binding_detail {
// Helper type alias for picking a script-exposable non-wrappercached XPIDL
// interface to expose to JS code. Falls back to `nsISupports` if the specific
// interface type is ambiguous.
template <typename T, typename = void>
struct GetScriptableInterfaceType {
using Type = nsISupports;
static_assert(std::is_base_of_v<nsISupports, T>,
"T must inherit from nsISupports");
};
template <typename T>
struct GetScriptableInterfaceType<
T, std::void_t<typename T::ScriptableInterfaceType>> {
using Type = typename T::ScriptableInterfaceType;
static_assert(std::is_base_of_v<Type, T>,
"T must inherit from ScriptableInterfaceType");
static_assert(std::is_base_of_v<nsISupports, Type>,
"ScriptableInterfaceType must inherit from nsISupports");
};
template <typename T>
using ScriptableInterfaceType = typename GetScriptableInterfaceType<T>::Type;
} // namespace binding_detail
// Accept objects that inherit from nsISupports but not nsWrapperCache (e.g.
// DOM File).
template <class T>
[[nodiscard]] std::enable_if_t<!std::is_base_of<nsWrapperCache, T>::value &&
!std::is_base_of<CallbackObject, T>::value &&
std::is_base_of<nsISupports, T>::value,
bool>
ToJSValue(JSContext* aCx, T& aArgument, JS::MutableHandle<JS::Value> aValue) {
// Make sure we're called in a compartment
MOZ_ASSERT(JS::CurrentGlobalOrNull(aCx));
xpcObjectHelper helper(ToSupports(&aArgument));
JS::Rooted<JSObject*> scope(aCx, JS::CurrentGlobalOrNull(aCx));
const nsIID& iid =
NS_GET_TEMPLATE_IID(binding_detail::ScriptableInterfaceType<T>);
return XPCOMObjectToJsval(aCx, scope, helper, &iid, true, aValue);
}
[[nodiscard]] bool ToJSValue(JSContext* aCx, const WindowProxyHolder& aArgument,
JS::MutableHandle<JS::Value> aValue);
// Accept nsRefPtr/nsCOMPtr
template <typename T>
[[nodiscard]] bool ToJSValue(JSContext* aCx, const nsCOMPtr<T>& aArgument,
JS::MutableHandle<JS::Value> aValue) {
return ToJSValue(aCx, *aArgument.get(), aValue);
}
template <typename T>
[[nodiscard]] bool ToJSValue(JSContext* aCx, const RefPtr<T>& aArgument,
JS::MutableHandle<JS::Value> aValue) {
return ToJSValue(aCx, *aArgument.get(), aValue);
}
template <typename T>
[[nodiscard]] bool ToJSValue(JSContext* aCx, const NonNull<T>& aArgument,
JS::MutableHandle<JS::Value> aValue) {
return ToJSValue(aCx, *aArgument.get(), aValue);
}
// Accept WebIDL dictionaries
template <class T>
[[nodiscard]] std::enable_if_t<std::is_base_of<DictionaryBase, T>::value, bool>
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
[[nodiscard]] inline bool ToJSValue(JSContext* aCx, const JS::Value& aArgument,
JS::MutableHandle<JS::Value> aValue) {
aValue.set(aArgument);
return MaybeWrapValue(aCx, aValue);
}
[[nodiscard]] inline bool ToJSValue(JSContext* aCx,
JS::Handle<JS::Value> aArgument,
JS::MutableHandle<JS::Value> aValue) {
aValue.set(aArgument);
return MaybeWrapValue(aCx, aValue);
}
// Accept existing JS values on the Heap (which may not be same-compartment with
// us
[[nodiscard]] inline bool ToJSValue(JSContext* aCx,
const JS::Heap<JS::Value>& aArgument,
JS::MutableHandle<JS::Value> aValue) {
aValue.set(aArgument);
return MaybeWrapValue(aCx, aValue);
}
// Accept existing rooted JS values (which may not be same-compartment with us
[[nodiscard]] inline bool ToJSValue(JSContext* aCx,
const JS::Rooted<JS::Value>& aArgument,
JS::MutableHandle<JS::Value> aValue) {
aValue.set(aArgument);
return MaybeWrapValue(aCx, aValue);
}
// Accept existing rooted JS objects (which may not be same-compartment with
// us).
[[nodiscard]] inline bool ToJSValue(JSContext* aCx,
const JS::Rooted<JSObject*>& aArgument,
JS::MutableHandle<JS::Value> aValue) {
aValue.setObjectOrNull(aArgument);
return MaybeWrapObjectOrNullValue(aCx, aValue);
}
// Accept nsresult, for use in rejections, and create an XPCOM
// exception object representing that nsresult.
[[nodiscard]] bool ToJSValue(JSContext* aCx, nsresult aArgument,
JS::MutableHandle<JS::Value> aValue);
// Accept ErrorResult, for use in rejections, and create an exception
// representing the failure. Note, the ErrorResult must indicate a failure
// with aArgument.Failure() returning true.
[[nodiscard]] bool ToJSValue(JSContext* aCx, ErrorResult&& aArgument,
JS::MutableHandle<JS::Value> aValue);
// Accept owning WebIDL unions.
template <typename T>
[[nodiscard]] std::enable_if_t<std::is_base_of<AllOwningUnionBase, T>::value,
bool>
ToJSValue(JSContext* aCx, const T& aArgument,
JS::MutableHandle<JS::Value> aValue) {
JS::Rooted<JSObject*> global(aCx, JS::CurrentGlobalOrNull(aCx));
return aArgument.ToJSVal(aCx, global, aValue);
}
// Accept pointers to other things we accept
template <typename T>
[[nodiscard]] std::enable_if_t<std::is_pointer<T>::value, bool> ToJSValue(
JSContext* aCx, T aArgument, JS::MutableHandle<JS::Value> aValue) {
return ToJSValue(aCx, *aArgument, aValue);
}
// Accept Promise objects, which need special handling.
[[nodiscard]] bool ToJSValue(JSContext* aCx, Promise& aArgument,
JS::MutableHandle<JS::Value> aValue);
// Accept arrays (and nested arrays) of other things we accept
template <typename T>
[[nodiscard]] bool ToJSValue(JSContext* aCx, T* aArguments, size_t aLength,
JS::MutableHandle<JS::Value> aValue);
template <typename T>
[[nodiscard]] bool ToJSValue(JSContext* aCx, const nsTArray<T>& aArgument,
JS::MutableHandle<JS::Value> aValue) {
return ToJSValue(aCx, aArgument.Elements(), aArgument.Length(), aValue);
}
template <typename T>
[[nodiscard]] 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>
[[nodiscard]] bool ToJSValue(JSContext* aCx, const T (&aArgument)[N],
JS::MutableHandle<JS::Value> aValue) {
return ToJSValue(aCx, aArgument, N, aValue);
}
// Accept arrays of other things we accept
template <typename T>
[[nodiscard]] 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::RootedVector<JS::Value> 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;
}
// Accept records of other things we accept. N.B. This assumes that
// keys are either UTF-8 or UTF-16-ish. See Bug 1706058.
template <typename K, typename V>
[[nodiscard]] bool ToJSValue(JSContext* aCx, const Record<K, V>& aArgument,
JS::MutableHandle<JS::Value> aValue) {
JS::RootedObject recordObj(aCx, JS_NewPlainObject(aCx));
if (!recordObj) {
return false;
}
for (auto& entry : aArgument.Entries()) {
JS::Rooted<JS::Value> value(aCx);
if (!ToJSValue(aCx, entry.mValue, &value)) {
return false;
}
if constexpr (std::is_same_v<nsCString, decltype(entry.mKey)>) {
NS_ConvertUTF8toUTF16 expandedKey(entry.mKey);
if (!JS_DefineUCProperty(aCx, recordObj, expandedKey.BeginReading(),
expandedKey.Length(), value, JSPROP_ENUMERATE)) {
return false;
}
} else {
if (!JS_DefineUCProperty(aCx, recordObj, entry.mKey.BeginReading(),
entry.mKey.Length(), value, JSPROP_ENUMERATE)) {
return false;
}
}
}
aValue.setObject(*recordObj);
return true;
}
} // namespace dom
} // namespace mozilla
#endif /* mozilla_dom_ToJSValue_h */
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