| /* |
| pybind11/detail/descr.h: Helper type for concatenating type signatures at compile time |
| |
| Copyright (c) 2016 Wenzel Jakob <wenzel.jakob@epfl.ch> |
| |
| All rights reserved. Use of this source code is governed by a |
| BSD-style license that can be found in the LICENSE file. |
| */ |
| |
| #pragma once |
| |
| #include "common.h" |
| |
| NAMESPACE_BEGIN(PYBIND11_NAMESPACE) |
| NAMESPACE_BEGIN(detail) |
| |
| #if !defined(_MSC_VER) |
| # define PYBIND11_DESCR_CONSTEXPR static constexpr |
| #else |
| # define PYBIND11_DESCR_CONSTEXPR const |
| #endif |
| |
| /* Concatenate type signatures at compile time */ |
| template <size_t N, typename... Ts> |
| struct descr { |
| char text[N + 1]; |
| |
| constexpr descr() : text{'\0'} { } |
| 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> |
| 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...>) { |
| 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> _(char const(&text)[N]) { return descr<N - 1>(text); } |
| constexpr descr<0> _(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...> { |
| 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>> _(char const(&text1)[N1], char const(&)[N2]) { |
| return _(text1); |
| } |
| template <bool B, size_t N1, size_t N2> |
| constexpr enable_if_t<!B, descr<N2 - 1>> _(char const(&)[N1], char const(&text2)[N2]) { |
| return _(text2); |
| } |
| |
| template <bool B, typename T1, typename T2> |
| constexpr enable_if_t<B, T1> _(const T1 &d, const T2 &) { return d; } |
| template <bool B, typename T1, typename T2> |
| constexpr enable_if_t<!B, T2> _(const T1 &, const T2 &d) { return d; } |
| |
| template <size_t Size> auto constexpr _() -> 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> _() { return {'%'}; } |
| |
| 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 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 + _(", ") + concat(args...); |
| } |
| |
| template <size_t N, typename... Ts> |
| constexpr descr<N + 2, Ts...> type_descr(const descr<N, Ts...> &descr) { |
| return _("{") + descr + _("}"); |
| } |
| |
| NAMESPACE_END(detail) |
| NAMESPACE_END(PYBIND11_NAMESPACE) |