/* 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)