utility.h

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#pragma once
#include "fl/stl/type_traits.h"
#include "fl/stl/noexcept.h"
 
namespace fl {

template <typename T = void> struct less {
    constexpr bool operator()(const T &lhs, const T &rhs) const FL_NOEXCEPT {
        return lhs < rhs;
    }
};

template <> struct less<void> {
    template <typename T, typename U>
    constexpr auto operator()(T &&lhs, U &&rhs) const FL_NOEXCEPT
        -> decltype(fl::forward<T>(lhs) < fl::forward<U>(rhs)) {
        return fl::forward<T>(lhs) < fl::forward<U>(rhs);
    }
};

template <typename T = void> struct greater {
    constexpr bool operator()(const T &lhs, const T &rhs) const FL_NOEXCEPT {
        return rhs < lhs;  // Equivalent to lhs > rhs, works with types that only have operator<
    }
};

template <> struct greater<void> {
    template <typename T, typename U>
    constexpr auto operator()(T &&lhs, U &&rhs) const FL_NOEXCEPT
        -> decltype(fl::forward<U>(rhs) < fl::forward<T>(lhs)) {
        return fl::forward<U>(rhs) < fl::forward<T>(lhs);  // Equivalent to lhs > rhs
    }
};
 
// Backward compatibility alias
template <typename T> using DefaultLess = less<T>;
 
} // namespace fl