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Fixes & improvements to FunctionWrapper

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- HandleValue needed to explicitly pass UndefinedHandleValue for
'default' arguments.
- Allow passing ScriptInterface as first argument.
- Statically check that a getter is provided for object methods instead
of crashing at runtime
- A few stylistic improvements

Differential Revision: https://code.wildfiregames.com/D3625
This was SVN commit r24981.
This commit is contained in:
wraitii 2021-03-02 16:55:22 +00:00
parent d8ea401a95
commit 2838873c0a
2 changed files with 54 additions and 9 deletions
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51
source/scriptinterface/FunctionWrapper.h
View File

@ -38,13 +38,18 @@ private:
/**
* In JS->C++ calls, types are converted using FromJSVal,
* and this requires them to be default-constructible (as that function takes an out parameter)
* thus constref needs to be removed when defining the tuple.
* Exceptions are:
* - const ScriptRequest& (as the first argument only, for implementation simplicity).
* - const ScriptInterface& (as the first argument only, for implementation simplicity).
* - JS::HandleValue
*/
template<typename T>
using type_transform = std::conditional_t<std::is_same_v<const ScriptRequest&, T>, const ScriptRequest&,
std::remove_const_t<typename std::remove_reference_t<T>>>;
using type_transform = std::conditional_t<
std::is_same_v<const ScriptRequest&, T> || std::is_same_v<const ScriptInterface&, T>,
T,
std::remove_const_t<typename std::remove_reference_t<T>>
>;
/**
* Convenient struct to get info on a [class] [const] function pointer.
@ -82,9 +87,16 @@ private:
// No need to convert JS values.
if constexpr (std::is_same_v<T, JS::HandleValue>)
{
// GCC (at least < 9) & VS17 prints warnings if arguments are not used in some constexpr branch.
UNUSED2(rq); UNUSED2(args); UNUSED2(went_ok);
return std::forward_as_tuple(args[idx]); // This passes the null handle value if idx is beyond the length of args.
// Default-construct values that aren't passed by JS.
// TODO: this should perhaps be removed, as it's distinct from C++ default values and kind of tricky.
if (idx >= args.length())
return std::forward_as_tuple(JS::UndefinedHandleValue);
else
{
// GCC (at least < 9) & VS17 prints warnings if arguments are not used in some constexpr branch.
UNUSED2(rq); UNUSED2(args); UNUSED2(went_ok);
return std::forward_as_tuple(args[idx]); // This passes the null handle value if idx is beyond the length of args.
}
}
else
{
@ -160,6 +172,20 @@ private:
return std::tuple_cat(std::forward_as_tuple(rq), DoConvertFromJS<0, Types...>(rq, args, went_ok));
}
// Overloads for ScriptInterface& first argument.
template<typename ...Types>
static std::tuple<const ScriptInterface&, Types...> ConvertFromJS(ScriptInterface::CmptPrivate* cmptPrivate, const ScriptRequest& rq, JS::CallArgs& args, bool& went_ok, std::tuple<const ScriptInterface&, Types...>*)
{
if constexpr (sizeof...(Types) == 0)
{
// GCC (at least < 9) & VS17 prints warnings if arguments are not used in some constexpr branch.
UNUSED2(rq); UNUSED2(args); UNUSED2(went_ok);
return std::forward_as_tuple(*cmptPrivate->pScriptInterface);
}
else
return std::tuple_cat(std::forward_as_tuple(*cmptPrivate->pScriptInterface), DoConvertFromJS<0, Types...>(rq, args, went_ok));
}
///////////////////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////////////
@ -212,6 +238,10 @@ public:
ScriptInterface* scriptInterface = ScriptInterface::GetScriptInterfaceAndCBData(cx)->pScriptInterface;
ScriptRequest rq(*scriptInterface);
// If the callable is an object method, we must specify how to fetch the object.
static_assert(std::is_same_v<typename args_info<decltype(callable)>::object_type, void> || thisGetter != nullptr,
"ScriptFunction::Register - No getter specified for object method");
// GCC 7 triggers spurious warnings
#ifdef __GNUC__
#pragma GCC diagnostic push
@ -267,6 +297,17 @@ public:
JS_DefineFunction(rq.cx, rq.nativeScope, name, &ToJSNative<callable, thisGetter>, args_info<decltype(callable)>::nb_args, flags);
}
/**
* Register a function on @param scope.
* Prefer the version taking ScriptRequest unless you have a good reason not to.
* @see Register
*/
template <auto callable, GetterFor<decltype(callable)> thisGetter = nullptr, u16 flags = JSPROP_ENUMERATE|JSPROP_READONLY|JSPROP_PERMANENT>
static void Register(JSContext* cx, JS::HandleObject scope, const char* name)
{
JS_DefineFunction(cx, scope, name, &ToJSNative<callable, thisGetter>, args_info<decltype(callable)>::nb_args, flags);
}
/**
* Convert the CmptPrivate callback data to T*
*/

12
source/scriptinterface/tests/test_FunctionWrapper.h
View File

@ -70,10 +70,14 @@ public:
void test_method_wrappers()
{
static_assert(std::is_same_v<decltype(&ScriptFunction::ToJSNative<&TestFunctionWrapper::test_method::method_1>), JSNative>);
static_assert(std::is_same_v<decltype(&ScriptFunction::ToJSNative<&TestFunctionWrapper::test_method::method_2>), JSNative>);
static_assert(std::is_same_v<decltype(&ScriptFunction::ToJSNative<&TestFunctionWrapper::test_method::const_method_1>), JSNative>);
static_assert(std::is_same_v<decltype(&ScriptFunction::ToJSNative<&TestFunctionWrapper::test_method::const_method_2>), JSNative>);
static_assert(std::is_same_v<decltype(&ScriptFunction::ToJSNative<&TestFunctionWrapper::test_method::method_1,
&ScriptFunction::ObjectFromCBData<test_method>>), JSNative>);
static_assert(std::is_same_v<decltype(&ScriptFunction::ToJSNative<&TestFunctionWrapper::test_method::method_2,
&ScriptFunction::ObjectFromCBData<test_method>>), JSNative>);
static_assert(std::is_same_v<decltype(&ScriptFunction::ToJSNative<&TestFunctionWrapper::test_method::const_method_1,
&ScriptFunction::ObjectFromCBData<test_method>>), JSNative>);
static_assert(std::is_same_v<decltype(&ScriptFunction::ToJSNative<&TestFunctionWrapper::test_method::const_method_2,
&ScriptFunction::ObjectFromCBData<test_method>>), JSNative>);
}
void test_calling()