Orange/include/Orange/Core/Traits.h

#pragma once

#include <Orange/Core/Types.h>

// Needed for placement new/delete.
#include <new>
#include <initializer_list>
#include <functional>

namespace orange
{
    template <typename Signature>
    using Function = std::function<Signature>;

    struct FalseType { static constexpr bool Value = false; };
    struct TrueType  { static constexpr bool Value = true;  };

    template <typename T> struct IsLValueReference     : FalseType {};
    template <typename T> struct IsLValueReference<T&> : TrueType {};

    template <typename T> struct RemoveReference_      { using Type = T; };
    template <typename T> struct RemoveReference_<T&>  { using Type = T; };
    template <typename T> struct RemoveReference_<T&&> { using Type = T; };

    template <typename T>
    using RemoveReference = typename RemoveReference_<T>::Type;

    template <typename T>
    constexpr T&& Forward(RemoveReference<T>& t) { return static_cast<T&&>(t); }

    template <typename T>
    constexpr T&& Forward(RemoveReference<T>&& t)
    {
        static_assert(!IsLValueReference<T>::Value, "Can not forward an rvalue as an lvalue.");
        return static_cast<T&&>(t);
    }

    template <typename T>
    constexpr RemoveReference<T>&& Move(T&& arg)
    {
        return static_cast<RemoveReference<T>&&>(arg);
    }

    template <typename ForwardIt>
    [[nodiscard]] constexpr ForwardIt MinElement(ForwardIt first, ForwardIt last)
    {
        if (first == last)
            return last;
    
        ForwardIt smallest = first;
        ++first;
        for (; first != last; ++first)
        {
            if (*first < *smallest)
                smallest = first;
        }
        return smallest;
    }

    template <typename ForwardIt, typename Compare>
    [[nodiscard]] constexpr ForwardIt MinElement(ForwardIt first, ForwardIt last, Compare comp)
    {
        if (first == last)
            return last;
    
        ForwardIt smallest = first;
        ++first;
        for (; first != last; ++first)
        {
            if (comp(*first, *smallest))
                smallest = first;
        }
        return smallest;
    }

    template <typename ForwardIt>
    [[nodiscard]] constexpr ForwardIt MaxElement(ForwardIt first, ForwardIt last)
    {
        if (first == last)
            return last;
    
        ForwardIt largest = first;
        ++first;
        for (; first != last; ++first)
        {
            if (*largest < *first)
                largest = first;
        }
        return largest;
    }

    template <typename ForwardIt, typename Compare>
    [[nodiscard]] constexpr ForwardIt MaxElement(ForwardIt first, ForwardIt last, Compare comp)
    {
        if (first == last)
            return last;
    
        ForwardIt largest = first;
        ++first;
        for (; first != last; ++first)
        {
            if (comp(*largest, *first))
                largest = first;
        }
        return largest;
    }

    template <typename T, size_t N>
    [[nodiscard]] constexpr size_t Size(const T (&array)[N]) noexcept
    {
        (void)array;
        return N;
    }

    template <typename T>
    [[nodiscard]] constexpr T Min(const T& valMin, const T& valMax)
    {
        return valMin < valMax ? valMin : valMax;
    }

    template <typename T>
    [[nodiscard]] constexpr T Min(std::initializer_list<T> ilist)
    {
        return *MinElement(ilist.begin(), ilist.end());
    }

    template <typename T, typename Compare>
    [[nodiscard]] constexpr T Min(std::initializer_list<T> ilist, Compare comp)
    {
        return *MinElement(ilist.begin(), ilist.end(), comp);
    }

    template <typename T>
    [[nodiscard]] constexpr T Max(const T& valMin, const T& valMax)
    {
        return valMin > valMax ? valMin : valMax;
    }

    template <typename T>
    [[nodiscard]] constexpr T Max(std::initializer_list<T> ilist)
    {
        return *MaxElement(ilist.begin(), ilist.end());
    }

    template <typename T, typename Compare>
    [[nodiscard]] constexpr T Max(std::initializer_list<T> ilist, Compare comp)
    {
        return *MaxElement(ilist.begin(), ilist.end(), comp);
    }

    template <typename T>
    [[nodiscard]] constexpr T Clamp( const T& val, const T& minVal, const T& maxVal )
    {
        return Min( Max( val, minVal ), maxVal );
    }

    template <typename T, typename U = T>
    [[nodiscard]] constexpr T Align(T what, U to)
    {
        return (what + to - 1) & ~(to - 1);
    }

    // Transformations


    namespace Util
    {
        template <typename InputIt, typename OutputIt, typename UnaryOperation>
        OutputIt Transform(InputIt inFirst,   InputIt inLast,
                        OutputIt outFirst, UnaryOperation unaryOp)
        {
            while (inFirst != inLast)
                *outFirst++ = unaryOp(*inFirst++);
            return outFirst;
        }

        template<typename InputIt1, typename InputIt2, typename OutputIt, typename BinaryOperation>
        OutputIt Transform(InputIt1 first1, InputIt1 last1, InputIt2 first2, 
                        OutputIt outFirst, BinaryOperation binOp)
        {
            while (first1 != last1)
                *outFirst++ = binOp(*first1++, *first2++);
            return outFirst;
        }

        template <typename T, typename InputIt, typename UnaryOperation>
        T TransformResult(InputIt first, InputIt last, UnaryOperation op)
        {
            T result;
            Transform(first, last, result.begin(), op);
            return result;
        }

        template <typename T, typename InputIt1, typename InputIt2, typename BinaryOperation>
        T TransformResult(InputIt1 first1, InputIt1 last1, InputIt2 first2, BinaryOperation op)
        {
            T result;
            Transform(first1, last1, first2, result.begin(), op);
            return result;
        }
    }

    template <typename InputIt, typename T>
    constexpr T Accumulate(InputIt first, InputIt last, T init)
    {
        for (; first != last; ++first)
            init = Move(init) + *first;
        return init;
    }

    template <typename InputIt, typename T, typename BinaryOperation>
    constexpr T Accumulate(InputIt first, InputIt last, T init, BinaryOperation op)
    {
        for (; first != last; ++first)
            init = op(Move(init), *first);
        return init;
    }

    template <typename InputIt1, typename InputIt2>
    bool Equal(InputIt1 first1, InputIt1 last1,  InputIt2 first2)
    {
        for (; first1 != last1; ++first1, ++first2)
        {
            if (!(*first1 == *first2))
                return false;
        }
        return true;
    }

    template <typename InputIt1, typename InputIt2, typename BinaryPredicate>
    bool Equal(InputIt1 first1, InputIt1 last1, InputIt2 first2, BinaryPredicate p)
    {
        for (; first1 != last1; ++first1, ++first2)
        {
            if (!p(*first1, *first2))
                return false;
        }
        return true;
    }

    template <typename InputIt, typename OutputIt>
    OutputIt Copy(InputIt first, InputIt last, OutputIt d_first)
    {
        for (; first != last; (void)++first, (void)++d_first)
            *d_first = *first;
        return d_first;
    }

    template <typename InputIt, typename OutputIt, typename UnaryPredicate>
    OutputIt CopyIf(InputIt first, InputIt last, 
                    OutputIt d_first, UnaryPredicate pred)
    {
        for (; first != last; ++first)
        {
            if (pred(*first))
            {
                *d_first = *first;
                ++d_first;
            }
        }
        return d_first;
    }

    template <typename ForwardIt, typename T>
    void Fill(ForwardIt first, ForwardIt last, const T& value)
    {
        for (; first != last; ++first)
            *first = value;
    }

    // Math ops
    namespace Math
    {
        template <typename T> T Negate(const T& x) { return -x; }

        template <typename T> T Add       (const T& x, const T& y) { return x + y; }
        template <typename T> T Subtract  (const T& x, const T& y) { return x - y; }
        template <typename T> T Multiply  (const T& x, const T& y) { return x * y; }
        template <typename T> T Divide    (const T& x, const T& y) { return x / y; }
        template <typename T> T Modulo    (const T& x, const T& y) { return x % y; }
    }
}