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// *****************************************************************************
// * This file is part of the FreeFileSync project. It is distributed under *
// * GNU General Public License: https://www.gnu.org/licenses/gpl-3.0 *
// * Copyright (C) Zenju (zenju AT freefilesync DOT org) - All Rights Reserved *
// *****************************************************************************
#ifndef TYPE_TRAITS_H_3425628658765467
#define TYPE_TRAITS_H_3425628658765467
#include <algorithm>
#include <type_traits>
//https://en.cppreference.com/w/cpp/header/type_traits
namespace zen
{
template <class T, class...>
struct GetFirstOf
{
using Type = T;
};
template <class... T> using GetFirstOfT = typename GetFirstOf<T...>::Type;
template <class F>
class FunctionReturnType
{
template <class R, class... Args> static R dummyFun(R(*)(Args...));
public:
using Type = decltype(dummyFun(F()));
};
template <class F> using FunctionReturnTypeT = typename FunctionReturnType<F>::Type;
//yes, there's std::invoke_result_t, but it requires to specify function argument types for no good reason
//=============================================================================
template <class T, size_t N>
constexpr uint32_t arrayHash(T (&arr)[N]) //don't bother making FNV1aHash constexpr instead
{
uint32_t hashVal = 2166136261U; //FNV-1a base
std::for_each(&arr[0], &arr[N], [&hashVal](T n)
{
//static_assert(isInteger<T> || std::is_same_v<T, char> || std::is_same_v<T, wchar_t>);
static_assert(sizeof(T) <= sizeof(hashVal));
hashVal ^= static_cast<uint32_t>(n);
hashVal *= 16777619U; //prime
});
return hashVal;
}
//Herb Sutter's signedness conversion helpers: https://herbsutter.com/2013/06/13/gotw-93-solution-auto-variables-part-2/
template <class T> inline auto makeSigned (T t) { return static_cast<std::make_signed_t <T>>(t); }
template <class T> inline auto makeUnsigned(T t) { return static_cast<std::make_unsigned_t<T>>(t); }
//################# Built-in Types ########################
//unfortunate standardized nonsense: std::is_integral<> includes bool, char, wchar_t! => roll our own:
template <class T> constexpr bool isUnsignedInt = std::is_same_v<std::remove_cv_t<T>, unsigned char> ||
std::is_same_v<std::remove_cv_t<T>, unsigned short int> ||
std::is_same_v<std::remove_cv_t<T>, unsigned int> ||
std::is_same_v<std::remove_cv_t<T>, unsigned long int> ||
std::is_same_v<std::remove_cv_t<T>, unsigned long long int>;
template <class T> constexpr bool isSignedInt = std::is_same_v<std::remove_cv_t<T>, signed char> ||
std::is_same_v<std::remove_cv_t<T>, short int> ||
std::is_same_v<std::remove_cv_t<T>, int> ||
std::is_same_v<std::remove_cv_t<T>, long int> ||
std::is_same_v<std::remove_cv_t<T>, long long int>;
template <class T> constexpr bool isInteger = isUnsignedInt<T> || isSignedInt<T>;
template <class T> constexpr bool isFloat = std::is_floating_point_v<T>;
template <class T> constexpr bool isArithmetic = isInteger<T> || isFloat<T>;
//################# Class Members ########################
/* Detect data or function members of a class by name: ZEN_INIT_DETECT_MEMBER + hasMember_
Example: 1. ZEN_INIT_DETECT_MEMBER(c_str);
2. hasMember_c_str<T> -> use boolean
Detect data or function members of a class by name *and* type: ZEN_INIT_DETECT_MEMBER2 + HasMember_
Example: 1. ZEN_INIT_DETECT_MEMBER2(size, size_t (T::*)() const);
2. hasMember_size<T>::value -> use as boolean
Detect member type of a class: ZEN_INIT_DETECT_MEMBER_TYPE + hasMemberType_
Example: 1. ZEN_INIT_DETECT_MEMBER_TYPE(value_type);
2. hasMemberType_value_type<T> -> use as boolean */
//########## Sorting ##############################
/*
Generate a descending binary predicate at compile time!
Usage:
static const bool ascending = ...
makeSortDirection(old binary predicate, std::bool_constant<ascending>()) -> new binary predicate
*/
template <class Predicate>
struct LessDescending
{
LessDescending(Predicate lessThan) : lessThan_(std::move(lessThan)) {}
template <class T> bool operator()(const T& lhs, const T& rhs) const { return lessThan_(rhs, lhs); }
private:
Predicate lessThan_;
};
template <class Predicate> inline
/**/ Predicate makeSortDirection(Predicate pred, std::true_type) { return pred; }
template <class Predicate> inline
LessDescending<Predicate> makeSortDirection(Predicate pred, std::false_type) { return pred; }
//################ implementation ######################
#define ZEN_INIT_DETECT_MEMBER(NAME) \
\
template<bool isClass, class T> \
struct HasMemberImpl_##NAME \
{ \
private: \
using Yes = char[1]; \
using No = char[2]; \
\
template <typename U, U t> \
class Helper {}; \
\
struct Fallback { int NAME; }; \
\
template <class U> \
struct Helper2 : public U, public Fallback {}; /*this works only for class types!!!*/ \
\
template <class U> static No& hasMember(Helper<int Fallback::*, &Helper2<U>::NAME>*); \
template <class U> static Yes& hasMember(...); \
public: \
enum { value = sizeof(hasMember<T>(nullptr)) == sizeof(Yes) }; \
}; \
\
template <class T> \
struct HasMemberImpl_##NAME<false, T> : std::false_type {}; \
\
template <class T> constexpr bool hasMember_##NAME = HasMemberImpl_##NAME<std::is_class_v<T>, T>::value;
//####################################################################
#define ZEN_INIT_DETECT_MEMBER2(NAME, TYPE) \
\
template<typename U> \
class HasMember_##NAME \
{ \
using Yes = char[1]; \
using No = char[2]; \
\
template <typename T, T t> class Helper {}; \
\
template <class T> static Yes& hasMember(Helper<TYPE, &T::NAME>*); \
template <class T> static No& hasMember(...); \
public: \
enum { value = sizeof(hasMember<U>(nullptr)) == sizeof(Yes) }; \
}; \
\
template <class T> constexpr bool hasMember_##NAME = HasMember_##NAME<T>::value;
//####################################################################
#define ZEN_INIT_DETECT_MEMBER_TYPE(TYPENAME) \
\
template<typename T> \
class HasMemberType_##TYPENAME \
{ \
using Yes = char[1]; \
using No = char[2]; \
\
template <typename U> class Helper {}; \
\
template <class U> static Yes& hasMemberType(Helper<typename U::TYPENAME>*); \
template <class U> static No& hasMemberType(...); \
public: \
enum { value = sizeof(hasMemberType<T>(nullptr)) == sizeof(Yes) }; \
}; \
\
template <class T> constexpr bool hasMemberType_##TYPENAME = HasMemberType_##TYPENAME<T>::value;
}
//---------------------------------------------------------------------------
//ZEN macro consistency checks: => place in most-used header!
#endif //TYPE_TRAITS_H_3425628658765467
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