PromotedType.h

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// PromotedType.h:
// ---------------
//

#ifndef __IPSDKUTIL_INSTRUCTIONSET_PROMOTEDTYPE_H__
#define __IPSDKUTIL_INSTRUCTIONSET_PROMOTEDTYPE_H__

#include <IPSDKUtil/IPSDKUtilExports.h>

#include <boost/type_traits/is_signed.hpp>


namespace ipsdk {

// choose the larger of two types
template<
      typename T1
    , typename T2
    , bool choose1 = (sizeof(T1) > sizeof(T2)) // hands off!
    >
struct choose_larger
{
    typedef T1 Type;
};

// specialization for the case where sizeof(T2) >= sizeof(T1)
template< typename T1, typename T2 >
struct choose_larger< T1, T2, false >
{
    typedef T2 Type;
};



// template PromotedType<T1, T2> declaration
template <typename T1, typename T2,
          typename Enable=void>
struct PromotedType
{
};

// specialization for case "T1 is integral, T2 is not"
template <typename T1, typename T2>
struct PromotedType<T1, T2, 
                        typename boost::enable_if_c<
                            boost::is_integral<T1>::value 
                            && !boost::is_integral<T2>::value
                        >::type
                    >
{
    typedef T2 Type;
};

// specialization for case "T2 is integral, T1 is not"
template <typename T1, typename T2>
struct PromotedType<T1, T2, 
                        typename boost::enable_if_c<
                            !boost::is_integral<T1>::value 
                            && boost::is_integral<T2>::value
                        >::type
                    >
{
    typedef T1 Type;
};

// specialization for case "T1 and T2 are both integral (or both not), and have
// different sizes"
template <typename T1, typename T2>
struct PromotedType<T1, T2,
                        typename boost::enable_if_c<
                            boost::is_integral<T1>::value == boost::is_integral<T2>::value
                            && sizeof(T1) != sizeof(T2)
                        >::type>
{
    typedef typename choose_larger<T1, T2>::Type Type;
};

// specialization for case "T1 and T2 have same type"
template <typename T1, typename T2>
struct PromotedType<T1, T2,
                        typename boost::enable_if_c<
                            boost::is_same<T1, T2>::value
                        >::type>
{
    typedef T1 Type;
};

// specialization for case "T1 and T2 are integers of same size; T1 is signed
// whereas T2 is unsigned"
template <typename T1, typename T2>
struct PromotedType<T1, T2,
                        typename boost::enable_if_c<
                            boost::is_integral<T1>::value
                            && boost::is_integral<T2>::value
                            && sizeof(T1) == sizeof(T2)
                            && boost::is_signed<T1>::value
                            && !boost::is_signed<T2>::value
                        >::type>
{
    typedef T2 Type;
};

// specialization for case "T1 and T2 are integers of same size; T1 is unsigned
// whereas T2 is signed"
template <typename T1, typename T2>
struct PromotedType<T1, T2,
                        typename boost::enable_if_c<
                            boost::is_integral<T1>::value
                            && boost::is_integral<T2>::value
                            && sizeof(T1) == sizeof(T2)
                            && !boost::is_signed<T1>::value
                            && boost::is_signed<T2>::value
                        >::type>
{
    typedef T1 Type;
};

// struct PromotedType3: gives the greatest type of 3
template <typename T1, typename T2, typename T3>
struct PromotedType3
{
    typedef
        typename PromotedType<typename PromotedType<T1, T2>::Type, T3>::Type  
        Type;
};


} // end of namespace ipsdk


#endif // __IPSDKUTIL_INSTRUCTIONSET_PROMOTEDTYPE_H__