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Use constexpr_first for args/kwargs positional checks

This commit is contained in:
Jason Rhinelander 2017-01-22 19:15:12 -05:00 committed by Wenzel Jakob
parent 34d308adf0
commit 70ed2a4897
1 changed files with 11 additions and 19 deletions
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30
include/pybind11/cast.h
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@ -1248,22 +1248,6 @@ NAMESPACE_BEGIN(detail)
// forward declaration
struct function_record;
// Helper struct to only allow py::args and/or py::kwargs at the end of the function arguments
template <bool args, bool kwargs, bool args_kwargs_are_last> struct assert_args_kwargs_must_be_last {
static constexpr bool has_args = args, has_kwargs = kwargs;
static_assert(args_kwargs_are_last, "py::args/py::kwargs are only permitted as the last argument(s) of a function");
};
template <typename... T> struct args_kwargs_must_be_last;
template <typename T1, typename... Tmore> struct args_kwargs_must_be_last<T1, Tmore...>
: args_kwargs_must_be_last<Tmore...> {};
template <typename... T> struct args_kwargs_must_be_last<args, T...>
: assert_args_kwargs_must_be_last<true, false, sizeof...(T) == 0> {};
template <typename... T> struct args_kwargs_must_be_last<kwargs, T...>
: assert_args_kwargs_must_be_last<false, true, sizeof...(T) == 0> {};
template <typename... T> struct args_kwargs_must_be_last<args, kwargs, T...>
: assert_args_kwargs_must_be_last<true, true, sizeof...(T) == 0> {};
template <> struct args_kwargs_must_be_last<> : assert_args_kwargs_must_be_last<false, false, true> {};
using function_arguments = const std::vector<handle> &;
/// Helper class which loads arguments for C++ functions called from Python
@ -1271,11 +1255,19 @@ template <typename... Args>
class argument_loader {
using indices = make_index_sequence<sizeof...(Args)>;
using check_args_kwargs = args_kwargs_must_be_last<intrinsic_t<Args>...>;
template <typename Arg> using argument_is_args = std::is_same<intrinsic_t<Arg>, args>;
template <typename Arg> using argument_is_kwargs = std::is_same<intrinsic_t<Arg>, kwargs>;
// Get args/kwargs argument positions relative to the end of the argument list:
static constexpr auto args_pos = constexpr_first<argument_is_args, Args...>() - (int) sizeof...(Args),
kwargs_pos = constexpr_first<argument_is_kwargs, Args...>() - (int) sizeof...(Args);
static constexpr bool args_kwargs_are_last = kwargs_pos >= - 1 && args_pos >= kwargs_pos - 1;
static_assert(args_kwargs_are_last, "py::args/py::kwargs are only permitted as the last argument(s) of a function");
public:
static constexpr bool has_kwargs = check_args_kwargs::has_kwargs;
static constexpr bool has_args = check_args_kwargs::has_args;
static constexpr bool has_kwargs = kwargs_pos < 0;
static constexpr bool has_args = args_pos < 0;
static PYBIND11_DESCR arg_names() { return detail::concat(make_caster<Args>::name()...); }