Differential D2818 Diff 12345 source/scriptinterface/NativeWrapperDecls.h

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source/scriptinterface/NativeWrapperDecls.h

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	* but WITHOUT ANY WARRANTY; without even the implied warranty of			* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the			* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.			* GNU General Public License for more details.
	*			*
	* You should have received a copy of the GNU General Public License			* 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/>.			* along with 0 A.D. If not, see <http://www.gnu.org/licenses/>.
	*/			*/

	#include <boost/preprocessor/punctuation/comma_if.hpp>
	#include <boost/preprocessor/repetition/repeat.hpp>

	// MaybeRef should be private, but has to be public due to a compiler bug in clang.
	// TODO: Make this private when the bug is fixed in all supported versions of clang.
	template <typename T> struct MaybeRef;

	// Define lots of useful macros:

	// Varieties of comma-separated list to fit on the head/tail/whole of another comma-separated list
	#define NUMBERED_LIST_HEAD(z, i, data) data##i,
	#define NUMBERED_LIST_TAIL(z, i, data) ,data##i
	#define NUMBERED_LIST_TAIL_MAYBE_REF(z, i, data) , typename MaybeRef<data##i>::Type
	#define NUMBERED_LIST_BALANCED(z, i, data) BOOST_PP_COMMA_IF(i) data##i
	#define NUMBERED_LIST_BALANCED_MAYBE_REF(z, i, data) BOOST_PP_COMMA_IF(i) typename MaybeRef<data##i>::Type

	// TODO: We allow optional parameters when the C++ type can be converted from JS::UndefinedValue.
	// FromJSVal is expected to either set a##i or return false (otherwise we could get undefined
	// behaviour because some types have undefined values when not being initialized).
	// This is not very clear and also a bit fragile. Another problem is that the error reporting lacks
	// a bit. SpiderMonkey will throw a JS exception and abort the execution of the current function when
	// we return false here (without printing a callstack or additional detail telling that an argument
	// conversion failed). So we have two TODOs here:
	// 1. On the conceptual side: How to consistently work with optional parameters (or drop them completely?)
	// 2. On the technical side: Improve error handling, find a better way to ensure parameters are initialized
	#define CONVERT_ARG(z, i, data) \
	bool typeConvRet##i; \
	T##i a##i = ScriptInterface::AssignOrFromJSVal<T##i>( \
	cx, \
	i < args.length() ? args[i] : JS::UndefinedHandleValue, \
	typeConvRet##i); \
	if (!typeConvRet##i) return false;

	// List-generating macros, named roughly after their first list item
	#define TYPENAME_T0_HEAD(z, i) BOOST_PP_REPEAT_##z (i, NUMBERED_LIST_HEAD, typename T) // "typename T0, typename T1, "
	#define T0(z, i) BOOST_PP_REPEAT_##z (i, NUMBERED_LIST_BALANCED, T) // "T0, T1"
	#define T0_MAYBE_REF(z, i) BOOST_PP_REPEAT_##z (i, NUMBERED_LIST_BALANCED_MAYBE_REF, T) // "const T0&, T1"
	#define T0_TAIL(z, i) BOOST_PP_REPEAT_##z (i, NUMBERED_LIST_TAIL, T) // ", T0, T1"
	#define T0_TAIL_MAYBE_REF(z, i) BOOST_PP_REPEAT_##z (i, NUMBERED_LIST_TAIL_MAYBE_REF, T) // ", const T0&, T1"
	#define A0_TAIL(z, i) BOOST_PP_REPEAT_##z (i, NUMBERED_LIST_TAIL, a) // ", a0, a1"

	// Define RegisterFunction<TR, T0..., f>
	#define OVERLOADS(z, i, data) \
	template <typename R, TYPENAME_T0_HEAD(z,i) R (fptr) ( ScriptInterface::CxPrivate T0_TAIL_MAYBE_REF(z,i) )> \
	void RegisterFunction(const char* name) const \
	{ \
	Register(name, call<R T0_TAIL(z,i), fptr>, nargs<T0(z,i)>()); \
	}
	BOOST_PP_REPEAT(SCRIPT_INTERFACE_MAX_ARGS, OVERLOADS, ~)
	#undef OVERLOADS

	// JSFastNative-compatible function that wraps the function identified in the template argument list
	// (Definition comes later, since it depends on some things we haven't defined yet)
	#define OVERLOADS(z, i, data) \
	template <typename R, TYPENAME_T0_HEAD(z,i) R (fptr) ( ScriptInterface::CxPrivate T0_TAIL_MAYBE_REF(z,i) )> \
	static bool call(JSContext* cx, uint argc, JS::Value* vp);
	BOOST_PP_REPEAT(SCRIPT_INTERFACE_MAX_ARGS, OVERLOADS, ~)
	#undef OVERLOADS

	// Similar, for class methods
	#define OVERLOADS(z, i, data) \
	template <typename R, TYPENAME_T0_HEAD(z,i) JSClass* CLS, typename TC, R (TC::*fptr) ( T0_MAYBE_REF(z,i) )> \
	static bool callMethod(JSContext* cx, uint argc, JS::Value* vp);
	BOOST_PP_REPEAT(SCRIPT_INTERFACE_MAX_ARGS, OVERLOADS, ~)
	#undef OVERLOADS

	// const methods
	#define OVERLOADS(z, i, data) \
	template <typename R, TYPENAME_T0_HEAD(z,i) JSClass* CLS, typename TC, R (TC::*fptr) ( T0_MAYBE_REF(z,i) ) const> \
	static bool callMethodConst(JSContext* cx, uint argc, JS::Value* vp);
	BOOST_PP_REPEAT(SCRIPT_INTERFACE_MAX_ARGS, OVERLOADS, ~)
	#undef OVERLOADS

	// Argument-number counter			// Argument-number counter
	template<typename... Ts>			template<typename... Ts>
	static size_t nargs() { return sizeof...(Ts); }			static size_t nargs() { return sizeof...(Ts); }

	// Call the named property on the given object			// Call the named property on the given object
	template<typename R, typename... Ts>			template<typename R, typename... Ts>
	bool CallFunction(JS::HandleValue val, const char* name, R& ret, const Ts&... params) const;			bool CallFunction(JS::HandleValue val, const char* name, R& ret, const Ts&... params) const;

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