multi_integer_concepts.h

// Description: Concepts for multi-integer

#ifndef PASTELSYS_MULTI_INTEGER_CONCEPTS_H
#define PASTELSYS_MULTI_INTEGER_CONCEPTS_H

#include "pastel/sys/integer/multi_integer.h"
#include "pastel/sys/integer/integer_concept.h"

namespace Pastel
{

    template <typename T>
    concept MultiInteger_Settings_Concept_ = requires {
        //! The type of the underlying word.
        /*!
       A double-word type integer is required to exist,
       so that multiplication of two words can be stored.

       Choosing this type other than uinteger_half is mainly 
       useful for testing the correctness of the 
       implementation, although for small bit-counts 
       one may also choose to minimize the wasted space 
       by choosing the basic type smaller.
       */
        typename T::Word;

        //! Word must be unsigned native type.
        requires std::is_unsigned_v<typename T::Word>;

        //! The number of bits in the integer.
        {T::N} -> std::convertible_to<integer>;

        // There must exist an unsigned native integer with 
        // double the number of bits in the word.
        requires std::is_integral_v<UIntegerOfSize<2 * SizeInBits<typename T::Word>::value>>;

        //! Whether to interpret as a signed integer.
        /*!
       If Signed is true, then the integer is interpreted
       as a signed integer in two's complement form.
       If Signed is false, then the integer is interpreted
       as an unsigned integer, so that it's always
       positive, and the arithmetic works modulo 2^N,
       except for the division.
       */
        {T::Signed} -> std::convertible_to<bool>;
    };

    template <typename T>
    concept MultiInteger_Settings_Concept =
        MultiInteger_Settings_Concept_<RemoveCvRef<T>>;

    struct MultiInteger_Settings_Archetype
    {
        static constexpr int N = 2;
        using Word = uint32;
        static constexpr bool Signed = true;
    };

    PASTEL_CONCEPT_CHECK(MultiInteger_Settings_Archetype, MultiInteger_Settings_Concept);

}

#endif