VoidCast.hpp

#pragma once
#ifndef __H__OCULAR_UTILITIES_VOID_CAST__H__
#define __H__OCULAR_UTILITIES_VOID_CAST__H__

#include <type_traits>

//------------------------------------------------------------------------------------------

template<typename T>
union OCULAR_INTERNAL_VoidCast
{
    T var;
    void* ptr;
};

template<typename T>
static typename std::enable_if<std::is_trivial<T>::value, T>::type void_cast(void* val)
{
    if(sizeof(T) <= sizeof(void*))
    {
        union OCULAR_INTERNAL_VoidCast<T> vcintern;
        vcintern.ptr = val;

        return vcintern.var;
    }
    else
    {
        // Hit on double, int64_t, etc. on 32-bit builds 
        return *(T*)(val);
    }
}

template<typename T>
static typename std::enable_if<std::is_trivial<T>::value, void*>::type void_cast(T const& t)
{
    if(sizeof(T) <= sizeof(void*))
    {
        union OCULAR_INTERNAL_VoidCast<T> vcintern;
        vcintern.var = t;

        return vcintern.ptr;
    }
    else
    {
        // Hit on double, int64_t, etc. on 32-bit builds
        return (void*)(&t);
    }
}

template<typename T>
static typename std::enable_if<!std::is_trivial<T>::value, T>::type void_cast(void* val) 
{
    // Potentially undefined behavior (if sizeof(T) != data size at address pointed to in void*)
    // But unions only allow trivial members, so no other option
    return *(T*)(val);
}

template<typename T>
static typename std::enable_if<!std::is_trivial<T>::value, void*>::type void_cast(T const& t) 
{
    // Potentially undefined behavior (if sizeof(T) != data size at address pointed to in void*)
    // But unions only allow trivial members, so no other option
    return (void*)(&t);
}

//------------------------------------------------------------------------------------------

#endif