wraitii
2838873c0a
- 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.
322 lines
13 KiB
C++
322 lines
13 KiB
C++
/* Copyright (C) 2021 Wildfire Games.
|
|
* This file is part of 0 A.D.
|
|
*
|
|
* 0 A.D. is free software: you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License as published by
|
|
* the Free Software Foundation, either version 2 of the License, or
|
|
* (at your option) any later version.
|
|
*
|
|
* 0 A.D. is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with 0 A.D. If not, see <http://www.gnu.org/licenses/>.
|
|
*/
|
|
|
|
#ifndef INCLUDED_FUNCTIONWRAPPER
|
|
#define INCLUDED_FUNCTIONWRAPPER
|
|
|
|
#include "ScriptInterface.h"
|
|
#include "ScriptExceptions.h"
|
|
|
|
/**
|
|
* This class introduces templates to conveniently wrap C++ functions in JSNative functions.
|
|
* This _is_ rather template heavy, so compilation times beware.
|
|
* The C++ code can have arbitrary arguments and arbitrary return types, so long
|
|
* as they can be converted to/from JS using ScriptInterface::ToJSVal (FromJSVal respectively),
|
|
* and they are default-constructible (TODO: that can probably changed).
|
|
* (This could be a namespace, but I like being able to specify public/private).
|
|
*/
|
|
class ScriptFunction {
|
|
private:
|
|
ScriptFunction() = delete;
|
|
ScriptFunction(const ScriptFunction&) = delete;
|
|
ScriptFunction(ScriptFunction&&) = delete;
|
|
|
|
/**
|
|
* 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> || 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.
|
|
* TODO VS19: I ran into a really weird bug with an auto specialisation on this taking function pointers.
|
|
* It'd be good to add it back once we upgrade.
|
|
*/
|
|
template <class T> struct args_info;
|
|
|
|
template<typename R, typename ...Types>
|
|
struct args_info<R(*)(Types ...)>
|
|
{
|
|
static constexpr const size_t nb_args = sizeof...(Types);
|
|
using return_type = R;
|
|
using object_type = void;
|
|
using arg_types = std::tuple<type_transform<Types>...>;
|
|
};
|
|
|
|
template<typename C, typename R, typename ...Types>
|
|
struct args_info<R(C::*)(Types ...)> : public args_info<R(*)(Types ...)> { using object_type = C; };
|
|
template<typename C, typename R, typename ...Types>
|
|
struct args_info<R(C::*)(Types ...) const> : public args_info<R(C::*)(Types ...)> {};
|
|
|
|
///////////////////////////////////////////////////////////////////////////
|
|
///////////////////////////////////////////////////////////////////////////
|
|
|
|
/**
|
|
* DoConvertFromJS takes a type, a JS argument, and converts.
|
|
* The type T must be default constructible (except for HandleValue, which is handled specially).
|
|
* (possible) TODO: this could probably be changed if FromJSVal had a different signature.
|
|
* @param went_ok - true if the conversion succeeded and went_ok was true before, false otherwise.
|
|
*/
|
|
template<size_t idx, typename T>
|
|
static std::tuple<T> DoConvertFromJS(const ScriptRequest& rq, JS::CallArgs& args, bool& went_ok)
|
|
{
|
|
// No need to convert JS values.
|
|
if constexpr (std::is_same_v<T, JS::HandleValue>)
|
|
{
|
|
// 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
|
|
{
|
|
// 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(T{});
|
|
else
|
|
{
|
|
T ret;
|
|
went_ok &= ScriptInterface::FromJSVal<T>(rq, args[idx], ret);
|
|
return std::forward_as_tuple(ret);
|
|
}
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Recursive wrapper: calls DoConvertFromJS for type T and recurses.
|
|
*/
|
|
template<size_t idx, typename T, typename V, typename ...Types>
|
|
static std::tuple<T, V, Types...> DoConvertFromJS(const ScriptRequest& rq, JS::CallArgs& args, bool& went_ok)
|
|
{
|
|
return std::tuple_cat(DoConvertFromJS<idx, T>(rq, args, went_ok), DoConvertFromJS<idx + 1, V, Types...>(rq, args, went_ok));
|
|
}
|
|
|
|
/**
|
|
* ConvertFromJS is a wrapper around DoConvertFromJS, and serves to:
|
|
* - unwrap the tuple types as a parameter pack
|
|
* - handle specific cases for the first argument (cmptPrivate, ScriptRequest).
|
|
*
|
|
* Trick: to unpack the types of the tuple as a parameter pack, we deduce them from the function signature.
|
|
* To do that, we want the tuple in the arguments, but we don't want to actually have to default-instantiate,
|
|
* so we'll pass a nullptr that's static_cast to what we want.
|
|
*/
|
|
template<typename ...Types>
|
|
static std::tuple<Types...> ConvertFromJS(ScriptInterface::CmptPrivate*, const ScriptRequest& rq, JS::CallArgs& args, bool& went_ok, std::tuple<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 {};
|
|
}
|
|
else
|
|
return DoConvertFromJS<0, Types...>(rq, args, went_ok);
|
|
}
|
|
|
|
// Overloads for CmptPrivate* first argument.
|
|
template<typename ...Types>
|
|
static std::tuple<ScriptInterface::CmptPrivate*, Types...> ConvertFromJS(ScriptInterface::CmptPrivate* cmptPrivate, const ScriptRequest& rq, JS::CallArgs& args, bool& went_ok, std::tuple<ScriptInterface::CmptPrivate*, 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);
|
|
}
|
|
else
|
|
return std::tuple_cat(std::forward_as_tuple(cmptPrivate), DoConvertFromJS<0, Types...>(rq, args, went_ok));
|
|
}
|
|
|
|
// Overloads for ScriptRequest& first argument.
|
|
template<typename ...Types>
|
|
static std::tuple<const ScriptRequest&, Types...> ConvertFromJS(ScriptInterface::CmptPrivate*, const ScriptRequest& rq, JS::CallArgs& args, bool& went_ok, std::tuple<const ScriptRequest&, Types...>*)
|
|
{
|
|
if constexpr (sizeof...(Types) == 0)
|
|
{
|
|
// GCC (at least < 9) & VS17 prints warnings if arguments are not used in some constexpr branch.
|
|
UNUSED2(args); UNUSED2(went_ok);
|
|
return std::forward_as_tuple(rq);
|
|
}
|
|
else
|
|
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));
|
|
}
|
|
|
|
///////////////////////////////////////////////////////////////////////////
|
|
///////////////////////////////////////////////////////////////////////////
|
|
|
|
/**
|
|
* Wrap std::apply for the case where we have an object method or a regular function.
|
|
*/
|
|
template <auto callable, typename T, typename tuple>
|
|
static typename args_info<decltype(callable)>::return_type call(T* object, tuple& args)
|
|
{
|
|
if constexpr(std::is_same_v<T, void>)
|
|
{
|
|
// GCC (at least < 9) & VS17 prints warnings if arguments are not used in some constexpr branch.
|
|
UNUSED2(object);
|
|
return std::apply(callable, args);
|
|
}
|
|
else
|
|
return std::apply(callable, std::tuple_cat(std::forward_as_tuple(*object), args));
|
|
}
|
|
|
|
///////////////////////////////////////////////////////////////////////////
|
|
///////////////////////////////////////////////////////////////////////////
|
|
public:
|
|
template <typename T>
|
|
using ObjectGetter = T*(*)(const ScriptRequest&, JS::CallArgs&);
|
|
|
|
// TODO: the fact that this takes class and not auto is to work around an odd VS17 bug.
|
|
// It can be removed with VS19.
|
|
template <class callableType>
|
|
using GetterFor = ObjectGetter<typename args_info<callableType>::object_type>;
|
|
|
|
/**
|
|
* The meat of this file. This wraps a C++ function into a JSNative,
|
|
* so that it can be called from JS and manipulated in Spidermonkey.
|
|
* Most C++ functions can be directly wrapped, so long as their arguments are
|
|
* convertible from JS::Value and their return value is convertible to JS::Value (or void)
|
|
* The C++ function may optionally take const ScriptRequest& or CmptPrivate* as its first argument.
|
|
* The function may be an object method, in which case you need to pass an appropriate getter
|
|
*
|
|
* Optimisation note: the ScriptRequest object is created even without arguments,
|
|
* as it's necessary for IsExceptionPending.
|
|
*
|
|
* @param thisGetter to get the object, if necessary.
|
|
*/
|
|
template <auto callable, GetterFor<decltype(callable)> thisGetter = nullptr>
|
|
static bool ToJSNative(JSContext* cx, unsigned argc, JS::Value* vp)
|
|
{
|
|
using ObjType = typename args_info<decltype(callable)>::object_type;
|
|
|
|
JS::CallArgs args = JS::CallArgsFromVp(argc, vp);
|
|
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
|
|
#pragma GCC diagnostic ignored "-Waddress"
|
|
#endif
|
|
ObjType* obj = nullptr;
|
|
if constexpr (thisGetter != nullptr)
|
|
{
|
|
obj = thisGetter(rq, args);
|
|
if (!obj)
|
|
return false;
|
|
}
|
|
#ifdef __GNUC__
|
|
#pragma GCC diagnostic pop
|
|
#endif
|
|
|
|
bool went_ok = true;
|
|
typename args_info<decltype(callable)>::arg_types outs = ConvertFromJS(ScriptInterface::GetScriptInterfaceAndCBData(cx), rq, args, went_ok, static_cast<typename args_info<decltype(callable)>::arg_types*>(nullptr));
|
|
if (!went_ok)
|
|
return false;
|
|
|
|
/**
|
|
* TODO: error handling isn't standard, and since this can call any C++ function,
|
|
* there's no simple obvious way to deal with it.
|
|
* For now we check for pending JS exceptions, but it would probably be nicer
|
|
* to standardise on something, or perhaps provide an "errorHandler" here.
|
|
*/
|
|
if constexpr (std::is_same_v<void, typename args_info<decltype(callable)>::return_type>)
|
|
call<callable>(obj, outs);
|
|
else if constexpr (std::is_same_v<JS::Value, typename args_info<decltype(callable)>::return_type>)
|
|
args.rval().set(call<callable>(obj, outs));
|
|
else
|
|
ScriptInterface::ToJSVal(rq, args.rval(), call<callable>(obj, outs));
|
|
|
|
return !ScriptException::IsPending(rq);
|
|
}
|
|
|
|
/**
|
|
* Return a function spec from a C++ function.
|
|
*/
|
|
template <auto callable, GetterFor<decltype(callable)> thisGetter = nullptr, u16 flags = JSPROP_ENUMERATE|JSPROP_READONLY|JSPROP_PERMANENT>
|
|
static JSFunctionSpec Wrap(const char* name)
|
|
{
|
|
return JS_FN(name, (&ToJSNative<callable>), args_info<decltype(callable)>::nb_args, flags);
|
|
}
|
|
|
|
/**
|
|
* Register a function on the native scope (usually 'Engine').
|
|
*/
|
|
template <auto callable, GetterFor<decltype(callable)> thisGetter = nullptr, u16 flags = JSPROP_ENUMERATE|JSPROP_READONLY|JSPROP_PERMANENT>
|
|
static void Register(const ScriptRequest& rq, const char* name)
|
|
{
|
|
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*
|
|
*/
|
|
template <typename T>
|
|
static T* ObjectFromCBData(const ScriptRequest& rq, JS::CallArgs&)
|
|
{
|
|
return static_cast<T*>(ScriptInterface::GetScriptInterfaceAndCBData(rq.cx)->pCBData);
|
|
}
|
|
};
|
|
|
|
#endif // INCLUDED_FUNCTIONWRAPPER
|