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/* | |
pybind11/detail/descr.h: Helper type for concatenating type signatures at compile time | |
Copyright (c) 2016 Wenzel Jakob <[email protected]> | |
All rights reserved. Use of this source code is governed by a | |
BSD-style license that can be found in the LICENSE file. | |
*/ | |
PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE) | |
PYBIND11_NAMESPACE_BEGIN(detail) | |
/* Concatenate type signatures at compile time */ | |
template <size_t N, typename... Ts> | |
struct descr { | |
char text[N + 1]{'\0'}; | |
constexpr descr() = default; | |
// NOLINTNEXTLINE(google-explicit-constructor) | |
constexpr descr(char const (&s)[N + 1]) : descr(s, make_index_sequence<N>()) {} | |
template <size_t... Is> | |
constexpr descr(char const (&s)[N + 1], index_sequence<Is...>) : text{s[Is]..., '\0'} {} | |
template <typename... Chars> | |
// NOLINTNEXTLINE(google-explicit-constructor) | |
constexpr descr(char c, Chars... cs) : text{c, static_cast<char>(cs)..., '\0'} {} | |
static constexpr std::array<const std::type_info *, sizeof...(Ts) + 1> types() { | |
return {{&typeid(Ts)..., nullptr}}; | |
} | |
}; | |
template <size_t N1, size_t N2, typename... Ts1, typename... Ts2, size_t... Is1, size_t... Is2> | |
constexpr descr<N1 + N2, Ts1..., Ts2...> plus_impl(const descr<N1, Ts1...> &a, | |
const descr<N2, Ts2...> &b, | |
index_sequence<Is1...>, | |
index_sequence<Is2...>) { | |
PYBIND11_WORKAROUND_INCORRECT_MSVC_C4100(b); | |
return {a.text[Is1]..., b.text[Is2]...}; | |
} | |
template <size_t N1, size_t N2, typename... Ts1, typename... Ts2> | |
constexpr descr<N1 + N2, Ts1..., Ts2...> operator+(const descr<N1, Ts1...> &a, | |
const descr<N2, Ts2...> &b) { | |
return plus_impl(a, b, make_index_sequence<N1>(), make_index_sequence<N2>()); | |
} | |
template <size_t N> | |
constexpr descr<N - 1> const_name(char const (&text)[N]) { | |
return descr<N - 1>(text); | |
} | |
constexpr descr<0> const_name(char const (&)[1]) { return {}; } | |
template <size_t Rem, size_t... Digits> | |
struct int_to_str : int_to_str<Rem / 10, Rem % 10, Digits...> {}; | |
template <size_t... Digits> | |
struct int_to_str<0, Digits...> { | |
// WARNING: This only works with C++17 or higher. | |
static constexpr auto digits = descr<sizeof...(Digits)>(('0' + Digits)...); | |
}; | |
// Ternary description (like std::conditional) | |
template <bool B, size_t N1, size_t N2> | |
constexpr enable_if_t<B, descr<N1 - 1>> const_name(char const (&text1)[N1], char const (&)[N2]) { | |
return const_name(text1); | |
} | |
template <bool B, size_t N1, size_t N2> | |
constexpr enable_if_t<!B, descr<N2 - 1>> const_name(char const (&)[N1], char const (&text2)[N2]) { | |
return const_name(text2); | |
} | |
template <bool B, typename T1, typename T2> | |
constexpr enable_if_t<B, T1> const_name(const T1 &d, const T2 &) { | |
return d; | |
} | |
template <bool B, typename T1, typename T2> | |
constexpr enable_if_t<!B, T2> const_name(const T1 &, const T2 &d) { | |
return d; | |
} | |
template <size_t Size> | |
auto constexpr const_name() -> remove_cv_t<decltype(int_to_str<Size / 10, Size % 10>::digits)> { | |
return int_to_str<Size / 10, Size % 10>::digits; | |
} | |
template <typename Type> | |
constexpr descr<1, Type> const_name() { | |
return {'%'}; | |
} | |
// If "_" is defined as a macro, py::detail::_ cannot be provided. | |
// It is therefore best to use py::detail::const_name universally. | |
// This block is for backward compatibility only. | |
// (The const_name code is repeated to avoid introducing a "_" #define ourselves.) | |
template <size_t N> | |
constexpr descr<N - 1> _(char const (&text)[N]) { | |
return const_name<N>(text); | |
} | |
template <bool B, size_t N1, size_t N2> | |
constexpr enable_if_t<B, descr<N1 - 1>> _(char const (&text1)[N1], char const (&text2)[N2]) { | |
return const_name<B, N1, N2>(text1, text2); | |
} | |
template <bool B, size_t N1, size_t N2> | |
constexpr enable_if_t<!B, descr<N2 - 1>> _(char const (&text1)[N1], char const (&text2)[N2]) { | |
return const_name<B, N1, N2>(text1, text2); | |
} | |
template <bool B, typename T1, typename T2> | |
constexpr enable_if_t<B, T1> _(const T1 &d1, const T2 &d2) { | |
return const_name<B, T1, T2>(d1, d2); | |
} | |
template <bool B, typename T1, typename T2> | |
constexpr enable_if_t<!B, T2> _(const T1 &d1, const T2 &d2) { | |
return const_name<B, T1, T2>(d1, d2); | |
} | |
template <size_t Size> | |
auto constexpr _() -> remove_cv_t<decltype(int_to_str<Size / 10, Size % 10>::digits)> { | |
return const_name<Size>(); | |
} | |
template <typename Type> | |
constexpr descr<1, Type> _() { | |
return const_name<Type>(); | |
} | |
constexpr descr<0> concat() { return {}; } | |
template <size_t N, typename... Ts> | |
constexpr descr<N, Ts...> concat(const descr<N, Ts...> &descr) { | |
return descr; | |
} | |
template <size_t N1, size_t N2, typename... Ts1, typename... Ts2> | |
constexpr descr<N1 + N2 + 2, Ts1..., Ts2...> operator,(const descr<N1, Ts1...> &a, | |
const descr<N2, Ts2...> &b) { | |
return a + const_name(", ") + b; | |
} | |
template <size_t N, typename... Ts, typename... Args> | |
constexpr auto concat(const descr<N, Ts...> &d, const Args &...args) { | |
return (d, ..., args); | |
} | |
template <size_t N, typename... Ts, typename... Args> | |
constexpr auto concat(const descr<N, Ts...> &d, const Args &...args) | |
-> decltype(std::declval<descr<N + 2, Ts...>>() + concat(args...)) { | |
return d + const_name(", ") + concat(args...); | |
} | |
template <size_t N, typename... Ts> | |
constexpr descr<N + 2, Ts...> type_descr(const descr<N, Ts...> &descr) { | |
return const_name("{") + descr + const_name("}"); | |
} | |
PYBIND11_NAMESPACE_END(detail) | |
PYBIND11_NAMESPACE_END(PYBIND11_NAMESPACE) | |