450 lines
18 KiB
C++
450 lines
18 KiB
C++
/*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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* Copyright 2015-2017 Danny Robson <danny@nerdcruft.net>
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*/
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#ifndef __UTIL_INTROSPECTION_HPP
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#define __UTIL_INTROSPECTION_HPP
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#include "preprocessor.hpp"
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#include "variadic.hpp"
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#include <array>
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#include <cstddef>
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#include <cstdint>
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#include <experimental/filesystem>
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#include <ostream>
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#include <string>
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#include <tuple>
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#include <utility>
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namespace util {
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// clang#18781: clang-3.9/clang-4.0 will not instantiate static constexpr
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// member variables from class specialisations, so we have to use detail
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// classes to hold the variables and instantiate _those_ members instead.
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template <typename T>
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struct type_name;
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#define CLANG_WORKAROUND(TYPE,TAG,NAME) \
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namespace detail { \
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struct type_name_##TAG { \
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static constexpr const char value[] = (NAME); \
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}; \
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} \
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\
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template <> \
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struct type_name<TYPE> : public detail::type_name_##TAG { };
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CLANG_WORKAROUND(bool,bool,"bool")
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CLANG_WORKAROUND(char,char,"char")
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CLANG_WORKAROUND(void*,voidp,"void*")
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CLANG_WORKAROUND( uint8_t, u08, "u08")
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CLANG_WORKAROUND(uint16_t, u16, "u16")
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CLANG_WORKAROUND(uint32_t, u32, "u32")
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CLANG_WORKAROUND(uint64_t, u64, "u64")
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CLANG_WORKAROUND( int8_t, s08, "s08")
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CLANG_WORKAROUND(int16_t, s16, "s16")
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CLANG_WORKAROUND(int32_t, s32, "s32")
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CLANG_WORKAROUND(int64_t, s64, "s64")
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CLANG_WORKAROUND(float, f32, "f32")
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CLANG_WORKAROUND(double, f64, "f64")
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CLANG_WORKAROUND(const char*, const_cstring, "cstring")
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CLANG_WORKAROUND(char*, cstring, "cstring")
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CLANG_WORKAROUND(std::string, string, "string")
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CLANG_WORKAROUND(std::experimental::filesystem::path, path, "path");
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#undef CLANG_WORKAROUND
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template <typename T>
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constexpr
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auto type_name_v = type_name<T>::value;
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template <typename T>
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const char*
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to_string (void)
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{ return type_name_v<T>; }
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///////////////////////////////////////////////////////////////////////////
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template <typename T>
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struct type_char;
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template <> struct type_char<float > { static constexpr char value = 'f'; };
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template <> struct type_char<double> { static constexpr char value = 'd'; };
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template <> struct type_char< int8_t> { static constexpr char value = 'i'; };
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template <> struct type_char< int16_t> { static constexpr char value = 'i'; };
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template <> struct type_char< int32_t> { static constexpr char value = 'i'; };
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template <> struct type_char< int64_t> { static constexpr char value = 'i'; };
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template <> struct type_char< uint8_t> { static constexpr char value = 'u'; };
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template <> struct type_char<uint16_t> { static constexpr char value = 'u'; };
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template <> struct type_char<uint32_t> { static constexpr char value = 'u'; };
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template <> struct type_char<uint64_t> { static constexpr char value = 'u'; };
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template <typename T>
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constexpr auto type_char_v = type_char<T>::value;
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///////////////////////////////////////////////////////////////////////////
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/// Lists valid values of an enumeration
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///
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/// E: enumeration type
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///
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/// Specialisations must provide the following constexpr:
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/// value_type: typename
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/// value_count: size_t
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/// values: static const std::array<value_type,value_count>
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template <
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typename E
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>
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struct enum_traits;
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///////////////////////////////////////////////////////////////////////////
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/// Defines specialisations for introspection data structures for an
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/// enum E, in namespace NS, with variadic values __VA_ARGS__.
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///
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/// Expects to be caleld from outside all namespaces.
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///
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/// XXX: If we define the constexpr fields in a template specialised class
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/// clang has trouble instantiating them (with std=c++1z) resulting in
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/// undefined symbols at link time. By using a simple struct and inheriting
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/// from it we can avoid this problem. Revist this solution at clang-4.0.
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#define INTROSPECTION_ENUM_DECL(NS,E, ...) \
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namespace util { \
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struct PASTE(__enum_traits_,E) { \
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using value_type = ::NS::E; \
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\
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static constexpr \
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size_t value_count = VA_ARGS_COUNT(__VA_ARGS__); \
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\
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static const \
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std::array<value_type,value_count> \
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values; \
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\
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static const \
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std::array<const char*,value_count> \
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names; \
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}; \
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\
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template <> \
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struct enum_traits<::NS::E> : public PASTE(__enum_traits_,E) \
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{ }; \
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\
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template <> \
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struct type_name<::NS::E> { \
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static constexpr const char ns[] = #NS; \
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static constexpr const char value[] = #E; \
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}; \
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} \
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///------------------------------------------------------------------------
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/// Declares specialisations for introspection data structures for an
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/// enum E, in namespace NS, with variadic values __VA_ARGS__.
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///
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/// Expects to be called from outside all namespaces.
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#define INTROSPECTION_ENUM_IMPL(NS,E, ...) \
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const \
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std::array< \
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util::enum_traits<::NS::E>::value_type, \
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util::enum_traits<::NS::E>::value_count \
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> PASTE(util::__enum_traits_,E)::values = { \
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MAP1(NAMESPACE_LIST, ::NS::E, __VA_ARGS__) \
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}; \
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\
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const \
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std::array< \
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const char*, \
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util::enum_traits<::NS::E>::value_count \
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> PASTE(util::__enum_traits_,E)::names = { \
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MAP0(STRINGIZE_LIST, __VA_ARGS__) \
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};
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///------------------------------------------------------------------------
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/// Defines an istream extraction operator for an enumeration E, within
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/// namespace NS
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///
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/// Expects to be called from outside all namespaces.
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///
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/// The user is responsible for specialising the ::util::enum_traits<NS::E>
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/// parameters which are used to drive the implementation (eg, through
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/// INTROSPECTION_ENUM_DECL, and INTROSPECTION_ENUM_IMPL).
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///
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/// For trivial enumerations INTROSPECTION_ENUM may be easier to use.
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#define INTROSPECTION_ENUM_ISTREAM(NS,E) \
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std::istream& \
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::NS::operator>> (std::istream &is, ::NS::E &e) \
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{ \
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using traits = util::enum_traits<::NS::E>; \
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\
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std::string name; \
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is >> name; \
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\
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std::transform (std::begin (name), \
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std::end (name), \
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std::begin (name), \
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::toupper); \
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\
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auto name_pos = std::find ( \
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std::cbegin (traits::names), \
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std::cend (traits::names), \
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name \
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); \
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\
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if (name_pos == std::cend (traits::names)) { \
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is.setstate (std::istream::failbit); \
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} else { \
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auto d = std::distance ( \
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std::begin (traits::names), \
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name_pos \
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); \
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\
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e = traits::values[d]; \
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} \
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\
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return is; \
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}
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/// Defines an ostream insertion operator for an enumeration E, within
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/// namespace NS.
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///
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/// Expects to be called from outside all namespaces.
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///
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/// The user is responsible for specialising the ::util::enum_traits<NS::E>
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/// parameters which are used to drive the implementation (eg, through
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/// INTROSPECTION_ENUM_DECL, and INTROSPECTION_ENUM_IMPL).
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///
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/// For trivial enumerations INTROSPECTION_ENUM may be easier to use.
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#define INTROSPECTION_ENUM_OSTREAM(NS,E) \
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std::ostream& \
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::NS::operator<< (std::ostream &os, ::NS::E e) \
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{ \
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using traits = ::util::enum_traits<::NS::E>; \
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\
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auto val_pos = std::find ( \
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std::cbegin (traits::values), \
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std::cend (traits::values), \
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e \
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); \
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\
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if (val_pos == std::cend (traits::values)) { \
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os.setstate (std::ostream::failbit); \
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} else { \
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auto d = std::distance ( \
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std::cbegin (traits::values), \
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val_pos \
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); \
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\
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os << traits::names[d]; \
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} \
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\
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return os; \
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}
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/// Defines an enum, its values, associated introspection structures, and
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/// istream and ostream operators.
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///
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/// This must be called from outside all namespaces as
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/// INTROSPECTION_ENUM_DECL and INTROSPECTION_ENUM_IMPL need to declare
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/// and define structures outside the user's namespace.
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///
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/// The enum will be defined inside an inline namespace to simplify the
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/// passing of parameters to functions which require some namespace
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/// prefixing. This shouldn't have a practical effect on user code.
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#define INTROSPECTION_ENUM(E, ...) \
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inline namespace detail_intr_enum { \
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enum E { __VA_ARGS__ }; \
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std::ostream& operator<< (std::ostream&, E); \
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std::istream& operator>> (std::istream&, E&); \
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} \
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INTROSPECTION_ENUM_DECL(detail_intr_enum,E,__VA_ARGS__) \
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INTROSPECTION_ENUM_IMPL(detail_intr_enum,E,__VA_ARGS__) \
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INTROSPECTION_ENUM_ISTREAM(detail_intr_enum,E) \
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INTROSPECTION_ENUM_OSTREAM(detail_intr_enum,E)
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#define INTROSPECTION_ENUM_CLASS(E, ...) \
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inline namespace detail_intr_enum { \
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enum class E { __VA_ARGS__ }; \
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std::ostream& operator<< (std::ostream&, E); \
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std::istream& operator>> (std::istream&, E&); \
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} \
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INTROSPECTION_ENUM_DECL(detail_intr_enum,E,__VA_ARGS__) \
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INTROSPECTION_ENUM_IMPL(detail_intr_enum,E,__VA_ARGS__) \
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INTROSPECTION_ENUM_ISTREAM(detail_intr_enum,E) \
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INTROSPECTION_ENUM_OSTREAM(detail_intr_enum,E)
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///////////////////////////////////////////////////////////////////////////
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/// Describes a single member variable in a type availabe for introspection
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///
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/// K: target class
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/// R: member type
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/// M: pointer-to-member
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template <
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class K,
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typename R,
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R K::*M
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>
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struct field
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{
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typedef K klass;
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typedef R type;
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static const std::string name;
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static const R& get (const K &k) { return k.*M; }
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static R& get ( K &k) { return k.*M; }
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static R& get ( K &&) = delete;
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};
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///////////////////////////////////////////////////////////////////////////
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/// Holds the fields of a type available for introspection
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///
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/// Specialise the following type struct with a 'fields' tuple of the
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/// members that should be accessed like below:
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///
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/// struct foo { int a; int b; };
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///
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/// template <> struct type<foo>
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/// {
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/// typedef std::tuple<
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/// field<foo,int,&foo::a>,
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/// field<foo,int,&foo::b>
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/// > fields;
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/// };
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///
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/// template <> const std::string field<foo,int,&foo::a>::name = "a";
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/// template <> const std::string field<foo,int,&foo::b>::name = "b";
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template <class K>
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struct type { };
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///////////////////////////////////////////////////////////////////////////
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/// traits class which converts an introspected type to a tuple
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///
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/// K: target class
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template <typename K>
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struct type_tuple;
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template <
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typename ...T
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> struct type_tuple<
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std::tuple<T...>
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> {
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typedef std::tuple<T...> type;
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};
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template <
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typename K,
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typename I = typename std::make_index_sequence<
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std::tuple_size<
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typename type<K>::fields
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>::value
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>
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> struct _type_tuple;
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template <
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typename K,
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size_t ...I
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> struct _type_tuple <
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K,
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std::index_sequence<I...>
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> {
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typedef std::tuple<
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typename std::tuple_element<
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I,
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typename type<K>::fields
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>::type::type...
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> type;
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};
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template <
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typename K
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> struct type_tuple {
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typedef typename _type_tuple<K>::type type;
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};
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///////////////////////////////////////////////////////////////////////////
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namespace detail {
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template <
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typename K,
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typename I = typename std::make_index_sequence<
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std::tuple_size<
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typename type<K>::fields
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>::value
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>
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>
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struct _as_tuple;
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template <
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typename K,
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size_t ...I
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>
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struct _as_tuple <
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K,
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std::index_sequence<I...>
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>
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{
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static typename type_tuple<K>::type
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make (const K &k)
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{
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return std::make_tuple (
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std::tuple_element<I, typename type<K>::fields>::type::get (k)...
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);
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}
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static auto make (K&&) = delete;
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};
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}
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/// Convert an introspection capable class instance into a tuple instance
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///
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/// K: source class
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template <typename K>
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auto
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as_tuple (const K &k)
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{
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return detail::_as_tuple<K>::make (k);
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}
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template <typename K>
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auto as_tuple (K &_k)
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{
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const K &k = _k;
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return as_tuple (k);
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}
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template <typename K>
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auto as_tuple (K&&) = delete;
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}
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#endif
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