mirror of
https://github.com/aantron/better-enums.git
synced 2025-12-06 16:56:42 +08:00
500 lines
17 KiB
C++
500 lines
17 KiB
C++
#pragma once
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#include <cstddef> // For size_t.
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#include <cstring> // For string and memory routines.
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#include <stdexcept>
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#include <type_traits>
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#include "enum_preprocessor_map.h"
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namespace _enum {
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#define _ENUM_WEAK __attribute__((weak))
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template <typename EnumType, typename Iterator>
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class _Iterable;
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template <typename Derived>
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class _BaseIterator {
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public:
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Derived& operator ++()
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{ ++_index; return static_cast<Derived&>(*this); }
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constexpr bool operator ==(const Derived &other) const
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{ return other._index == _index; }
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constexpr bool operator !=(const Derived &other) const
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{ return other._index != _index; }
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protected:
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constexpr _BaseIterator(size_t index) : _index(index) { }
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size_t _index;
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};
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template <typename EnumType>
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class _ValueIterator :
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public _BaseIterator<_ValueIterator<EnumType>> {
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using _Super = _BaseIterator<_ValueIterator<EnumType>>;
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public:
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constexpr typename EnumType::Enumerated operator *() const
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{ return EnumType::_value_array[_Super::_index]; }
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private:
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using _Super::_Super;
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friend _Iterable<EnumType, _ValueIterator<EnumType>>;
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};
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template <typename EnumType>
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class _NameIterator :
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public _BaseIterator<_NameIterator<EnumType>> {
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using _Super = _BaseIterator<_NameIterator<EnumType>>;
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public:
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const char* operator *() const
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{ return EnumType::_getProcessedName(_Super::_index); }
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private:
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using _Super::_Super;
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friend _Iterable<EnumType, _NameIterator<EnumType>>;
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};
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template <typename EnumType, typename Iterator>
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class _Iterable {
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public:
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using iterator = Iterator;
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constexpr iterator begin() const { return iterator(0); }
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constexpr iterator end() const { return iterator(EnumType::size); }
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constexpr size_t size() const { return EnumType::size; }
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private:
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constexpr _Iterable() { };
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friend EnumType;
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};
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template <typename UnderlyingType>
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class _eat_assign {
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private:
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UnderlyingType _value;
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public:
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explicit constexpr _eat_assign(UnderlyingType value) : _value(value) { }
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template <typename Any>
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constexpr UnderlyingType operator =(Any dummy) const
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{ return _value; }
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constexpr operator UnderlyingType () const { return _value; }
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};
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#define _ENUM_EAT_ASSIGN_SINGLE(UnderlyingType, expression) \
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((_enum::_eat_assign<UnderlyingType>)UnderlyingType::expression)
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#define _ENUM_EAT_ASSIGN(UnderlyingType, ...) \
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_ENUM_PP_MAP(_ENUM_EAT_ASSIGN_SINGLE, UnderlyingType, __VA_ARGS__)
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#define _ENUM_STRINGIZE_SINGLE(ignored, expression) #expression
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#define _ENUM_STRINGIZE(...) \
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_ENUM_PP_MAP(_ENUM_STRINGIZE_SINGLE, ignored, __VA_ARGS__)
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#define _ENUM_NAME_ENDERS "= \t\n"
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constexpr bool _endsName(char c, size_t index = 0)
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{
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return
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// First, test whether c is equal to the current character in
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// _ENUM_NAME_ENDERS. In the case where c is the null terminator, this
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// will cause _endsName to return true when it has exhausted
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// _ENUM_NAME_ENDERS.
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c == _ENUM_NAME_ENDERS[index] ? true :
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// If _ENUM_NAME_ENDERS has been exhausted and c never matched, return
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// false.
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_ENUM_NAME_ENDERS[index] == '\0' ? false :
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// Otherwise, go on to the next character in _ENUM_ENDERS.
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_endsName(c, index + 1);
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}
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constexpr char _toLowercaseAscii(char c)
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{
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return c >= 0x41 && c <= 0x5A ? c + 0x20 : c;
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}
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constexpr bool _namesMatch(const char *stringizedName,
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const char *referenceName,
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size_t index = 0)
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{
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return
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// If the current character in the stringized name is a name ender,
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// return true if the reference name ends as well, and false otherwise.
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_endsName(stringizedName[index]) ? referenceName[index] == '\0' :
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// The current character in the stringized name is not a name ender. If
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// the reference name ended, then it is too short, so return false.
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referenceName[index] == '\0' ? false :
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// Neither name has ended. If the two current characters don't match,
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// return false.
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stringizedName[index] !=
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referenceName[index] ? false :
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// Otherwise, if the characters match, continue by comparing the rest of
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// the names.
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_namesMatch(stringizedName, referenceName, index + 1);
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}
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constexpr bool _namesMatchNocase(const char *stringizedName,
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const char *referenceName,
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size_t index = 0)
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{
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return
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_endsName(stringizedName[index]) ? referenceName[index] == '\0' :
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referenceName[index] == '\0' ? false :
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_toLowercaseAscii(stringizedName[index]) !=
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_toLowercaseAscii(referenceName[index]) ? false :
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_namesMatchNocase(stringizedName, referenceName, index + 1);
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}
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template <typename UnderlyingType>
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constexpr UnderlyingType _findMinLoop(const UnderlyingType *values,
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size_t valueCount, size_t index,
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UnderlyingType best)
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{
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return
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index == valueCount ? best :
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values[index] < best ?
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_findMinLoop(values, valueCount, index + 1, values[index]) :
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_findMinLoop(values, valueCount, index + 1, best);
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}
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template <typename UnderlyingType>
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constexpr UnderlyingType _findMin(const UnderlyingType *values,
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size_t valueCount)
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{
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return _findMinLoop(values, valueCount, 1, values[0]);
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}
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template <typename UnderlyingType>
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constexpr UnderlyingType _findMaxLoop(const UnderlyingType *values,
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size_t valueCount, size_t index,
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UnderlyingType best)
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{
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return
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index == valueCount ? best :
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values[index] > best ?
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_findMaxLoop(values, valueCount, index + 1, values[index]) :
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_findMaxLoop(values, valueCount, index + 1, best);
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}
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template <typename UnderlyingType>
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constexpr UnderlyingType _findMax(const UnderlyingType *values, size_t count)
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{
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return _findMaxLoop(values, count, 1, values[0]);
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}
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static inline const char * const* _processNames(const char * const *rawNames,
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size_t count)
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{
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// Allocate the replacement names array.
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const char **processedNames = new const char*[count];
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if (processedNames == nullptr)
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return nullptr;
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// Count the number of bytes needed in the replacement names array (an upper
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// bound).
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size_t bytesNeeded = 0;
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for (size_t index = 0; index < count; ++index)
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bytesNeeded += std::strlen(rawNames[index]) + 1;
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// Allocate memory for the string data.
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char *nameStorage = new char[bytesNeeded];
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if (nameStorage == nullptr) {
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delete[] processedNames;
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return nullptr;
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}
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// Trim each name and place the result in storage, then save a pointer to
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// it.
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char *writePointer = nameStorage;
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for (size_t index = 0; index < count; ++index) {
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const char *nameEnd =
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std::strpbrk(rawNames[index], _ENUM_NAME_ENDERS);
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size_t symbolCount =
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nameEnd == nullptr ?
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std::strlen(rawNames[index]) :
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nameEnd - rawNames[index];
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std::strncpy(writePointer, rawNames[index], symbolCount);
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processedNames[index] = writePointer;
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writePointer += symbolCount;
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*writePointer = '\0';
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++writePointer;
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}
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return processedNames;
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}
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template <typename EnumType> class _GeneratedArrays;
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} // namespace _enum
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#define _ENUM_ARRAYS(EnumType, IntegralType, ...) \
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enum class EnumType : IntegralType { __VA_ARGS__ }; \
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\
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namespace _enum { \
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\
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template <> \
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class _GeneratedArrays<EnumType> { \
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protected: \
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using Integral = IntegralType; \
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using Enumerated = EnumType; \
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\
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public: \
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constexpr static const char* name = #EnumType; \
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\
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protected: \
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constexpr static Enumerated _value_array[] = \
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{ _ENUM_EAT_ASSIGN(Enumerated, __VA_ARGS__) }; \
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\
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constexpr static const char *_name_array[] = \
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{ _ENUM_STRINGIZE(__VA_ARGS__) }; \
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}; \
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\
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}
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#define _ENUM_NOT_FOUND ((size_t)-1)
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namespace enum_ {
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template <typename EnumType>
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class traits : public _enum::_GeneratedArrays<EnumType> {
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protected:
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using _arrays = _enum::_GeneratedArrays<EnumType>;
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using _arrays::_value_array;
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using _arrays::_name_array;
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public:
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using typename _arrays::Enumerated;
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using typename _arrays::Integral;
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constexpr static const size_t size =
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sizeof(_value_array) / sizeof(Enumerated);
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static_assert(size > 0, "no constants defined in enum type");
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constexpr static const Enumerated first = _value_array[0];
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constexpr static const Enumerated last = _value_array[size - 1];
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constexpr static const Enumerated min =
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_enum::_findMin(_value_array, size);
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constexpr static const Enumerated max =
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_enum::_findMax(_value_array, size);
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constexpr static const size_t span =
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(Integral)max - (Integral)min + 1;
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constexpr static Integral to_integral(Enumerated value)
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{
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return (Integral)value;
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}
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constexpr static const Enumerated from_integral(Integral value)
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{
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return _value_array[_from_int_loop(value, true)];
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}
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constexpr static const Enumerated from_integral_unchecked(Integral value)
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{
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return (Enumerated)value;
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}
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static const char* to_string(Enumerated value)
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{
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_processNames();
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for (size_t index = 0; index < size; ++index) {
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if (_value_array[index] == value)
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return _processedNames[index];
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}
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throw std::domain_error("Enum::_to_string: invalid enum value");
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}
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constexpr static const Enumerated from_string(const char *name)
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{
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return _value_array[_from_string_loop(name, true)];
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}
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constexpr static const Enumerated from_string_nocase(const char *name)
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{
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return _value_array[_from_string_nocase_loop(name, true)];
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}
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constexpr static bool is_valid(Integral value)
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{
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return _from_int_loop(value, false) != _ENUM_NOT_FOUND;
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}
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constexpr static bool is_valid(const char *name)
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{
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return _from_string_loop(name, false) != _ENUM_NOT_FOUND;
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}
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constexpr static bool is_valid_nocase(const char *name)
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{
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return _from_string_nocase_loop(name, false) != _ENUM_NOT_FOUND;
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}
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protected:
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static const char * const *_processedNames;
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static void _processNames()
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{
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if (_processedNames == nullptr)
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_processedNames = _enum::_processNames(_name_array, size);
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}
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static const char* _getProcessedName(size_t index)
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{
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_processNames();
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return _processedNames[index];
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}
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using _ValueIterable =
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_enum::_Iterable<traits, _enum::_ValueIterator<traits>>;
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using _NameIterable =
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_enum::_Iterable<traits, _enum::_NameIterator<traits>>;
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friend _enum::_ValueIterator<traits>;
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friend _enum::_NameIterator<traits>;
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public:
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static const _ValueIterable values;
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static const _NameIterable names;
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protected:
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constexpr static size_t _from_int_loop(Integral value,
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bool throw_exception,
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size_t index = 0)
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{
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return
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index == size ?
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(throw_exception ?
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throw std::runtime_error(
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"enum_::traits::from_integral: invalid integer value") :
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_ENUM_NOT_FOUND) :
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(Integral)_value_array[index] == value ? index :
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_from_int_loop(value, throw_exception, index + 1);
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}
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constexpr static size_t _from_string_loop(const char *name,
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bool throw_exception,
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size_t index = 0)
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{
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return
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index == size ?
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(throw_exception ?
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throw std::runtime_error(
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"enum_::traits::from_string: invalid string argument") :
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_ENUM_NOT_FOUND) :
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_enum::_namesMatch(_name_array[index], name) ? index :
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_from_string_loop(name, throw_exception, index + 1);
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}
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constexpr static size_t _from_string_nocase_loop(const char *name,
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bool throw_exception,
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size_t index = 0)
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{
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return
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index == size ?
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(throw_exception ?
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throw std::runtime_error(
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"enum::traits::_from_string_nocase: "
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"invalid string argument") :
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_ENUM_NOT_FOUND) :
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_enum::_namesMatchNocase(_name_array[index], name) ? index :
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_from_string_nocase_loop(name, throw_exception, index + 1);
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}
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};
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template <typename Enum>
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constexpr typename traits<Enum>::Integral to_integral(Enum value)
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{
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return traits<Enum>::to_integral(value);
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}
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template <typename Enum>
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constexpr Enum from_integral(typename traits<Enum>::Integral value)
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{
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return traits<Enum>::from_integral(value);
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}
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template <typename Enum>
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constexpr Enum from_integral_unchecked(typename traits<Enum>::Integral value)
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{
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return traits<Enum>::from_integral_unchecked(value);
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}
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template <typename Enum>
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const char* to_string(Enum value)
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{
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return traits<Enum>::to_string(value);
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}
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template <typename Enum>
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constexpr Enum from_string(const char *name)
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{
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return traits<Enum>::from_string(name);
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}
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template <typename Enum>
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constexpr Enum from_string_nocase(const char *name)
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{
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return traits<Enum>::from_string_nocase(name);
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}
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} // namespace enum_
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#define _ENUM_GLOBALS(EnumType) \
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namespace _enum { \
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\
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constexpr _GeneratedArrays<EnumType>::Enumerated _ENUM_WEAK \
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_GeneratedArrays<EnumType>::_value_array[]; \
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\
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constexpr const char * _ENUM_WEAK \
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_GeneratedArrays<EnumType>::_name_array[]; \
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\
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} \
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\
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template <> \
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constexpr enum_::traits<EnumType>::_ValueIterable _ENUM_WEAK \
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enum_::traits<EnumType>::values{}; \
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\
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template <> \
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constexpr enum_::traits<EnumType>::_NameIterable _ENUM_WEAK \
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enum_::traits<EnumType>::names{}; \
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\
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template <> \
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const char * const * _ENUM_WEAK enum_::traits<EnumType>::_processedNames = \
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nullptr;
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#define ENUM(EnumType, Integral, ...) \
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_ENUM_ARRAYS(EnumType, Integral, __VA_ARGS__); \
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_ENUM_GLOBALS(EnumType);
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