//  Boost common_factor_ct.hpp header file  ----------------------------------//

//  (C) Copyright Daryle Walker and Stephen Cleary 2001-2002.

//  Distributed under the Boost Software License, Version 1.0. (See

//  accompanying file LICENSE_1_0.txt or copy at

//  http://www.boost.org/LICENSE_1_0.txt)

//  See http://www.boost.org for updates, documentation, and revision history. 

#ifndef BOOST_MATH_COMMON_FACTOR_CT_HPP

#define BOOST_MATH_COMMON_FACTOR_CT_HPP

#include <boost/math_fwd.hpp>  // self include

#include <boost/config.hpp>  // for BOOST_STATIC_CONSTANT, etc.

namespace boost

{

namespace math

{

//  Implementation details  --------------------------------------------------//

namespace detail

{

#ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION

    // Build GCD with Euclid's recursive algorithm

    template < unsigned long Value1, unsigned long Value2 >

    struct static_gcd_helper_t

    {

    private:

        BOOST_STATIC_CONSTANT( unsigned long, new_value1 = Value2 );

        BOOST_STATIC_CONSTANT( unsigned long, new_value2 = Value1 % Value2 );

        #ifndef __BORLANDC__

        #define BOOST_DETAIL_GCD_HELPER_VAL(Value) static_cast<unsigned long>(Value)

        #else

        typedef static_gcd_helper_t  self_type;

        #define BOOST_DETAIL_GCD_HELPER_VAL(Value)  (self_type:: Value )

        #endif

        typedef static_gcd_helper_t< BOOST_DETAIL_GCD_HELPER_VAL(new_value1),

         BOOST_DETAIL_GCD_HELPER_VAL(new_value2) >  next_step_type;

        #undef BOOST_DETAIL_GCD_HELPER_VAL

    public:

        BOOST_STATIC_CONSTANT( unsigned long, value = next_step_type::value );

    };

    // Non-recursive case

    template < unsigned long Value1 >

    struct static_gcd_helper_t< Value1, 0UL >

    {

        BOOST_STATIC_CONSTANT( unsigned long, value = Value1 );

    };

#else

    // Use inner class template workaround from Peter Dimov

    template < unsigned long Value1 >

    struct static_gcd_helper2_t

    {

        template < unsigned long Value2 >

        struct helper

        {

            BOOST_STATIC_CONSTANT( unsigned long, value

             = static_gcd_helper2_t<Value2>::BOOST_NESTED_TEMPLATE

             helper<Value1 % Value2>::value );

        };

        template <  >

        struct helper< 0UL >

        {

            BOOST_STATIC_CONSTANT( unsigned long, value = Value1 );

        };

    };

    // Special case

    template <  >

    struct static_gcd_helper2_t< 0UL >

    {

        template < unsigned long Value2 >

        struct helper

        {

            BOOST_STATIC_CONSTANT( unsigned long, value = Value2 );

        };

    };

    // Build the GCD from the above template(s)

    template < unsigned long Value1, unsigned long Value2 >

    struct static_gcd_helper_t

    {

        BOOST_STATIC_CONSTANT( unsigned long, value

         = static_gcd_helper2_t<Value1>::BOOST_NESTED_TEMPLATE

         helper<Value2>::value );

    };

#endif

#ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION

    // Build the LCM from the GCD

    template < unsigned long Value1, unsigned long Value2 >

    struct static_lcm_helper_t

    {

        typedef static_gcd_helper_t<Value1, Value2>  gcd_type;

        BOOST_STATIC_CONSTANT( unsigned long, value = Value1 / gcd_type::value

         * Value2 );

    };

    // Special case for zero-GCD values

    template < >

    struct static_lcm_helper_t< 0UL, 0UL >

    {

        BOOST_STATIC_CONSTANT( unsigned long, value = 0UL );

    };

#else

    // Adapt GCD's inner class template workaround for LCM

    template < unsigned long Value1 >

    struct static_lcm_helper2_t

    {

        template < unsigned long Value2 >

        struct helper

        {

            typedef static_gcd_helper_t<Value1, Value2>  gcd_type;

            BOOST_STATIC_CONSTANT( unsigned long, value = Value1

             / gcd_type::value * Value2 );

        };

        template <  >

        struct helper< 0UL >

        {

            BOOST_STATIC_CONSTANT( unsigned long, value = 0UL );

        };

    };

    // Special case

    template <  >

    struct static_lcm_helper2_t< 0UL >

    {

        template < unsigned long Value2 >

        struct helper

        {

            BOOST_STATIC_CONSTANT( unsigned long, value = 0UL );

        };

    };

    // Build the LCM from the above template(s)

    template < unsigned long Value1, unsigned long Value2 >

    struct static_lcm_helper_t

    {

        BOOST_STATIC_CONSTANT( unsigned long, value

         = static_lcm_helper2_t<Value1>::BOOST_NESTED_TEMPLATE

         helper<Value2>::value );

    };

#endif

}  // namespace detail

//  Compile-time greatest common divisor evaluator class declaration  --------//

template < unsigned long Value1, unsigned long Value2 >

struct static_gcd

{

    BOOST_STATIC_CONSTANT( unsigned long, value

     = (detail::static_gcd_helper_t<Value1, Value2>::value) );

};  // boost::math::static_gcd

//  Compile-time least common multiple evaluator class declaration  ----------//

template < unsigned long Value1, unsigned long Value2 >

struct static_lcm

{

    BOOST_STATIC_CONSTANT( unsigned long, value

     = (detail::static_lcm_helper_t<Value1, Value2>::value) );

};  // boost::math::static_lcm

}  // namespace math

}  // namespace boost

#endif  // BOOST_MATH_COMMON_FACTOR_CT_HPP