memmove in D

gistfile1.d

void* memmove(void* dest_, const void* src_, size_t n)
{
    auto dest = (cast(byte*)dest_)[0..n];
    auto src = (cast(byte*)src_)[0..n];
    if (dest.ptr < src.ptr || (src.ptr < dest.ptr && src.ptr+n < dest.ptr))
    {
        // move forward order
        foreach(i; 0..n)
        {
            dest[i] = src[i];
        }
    }
    else if (src.ptr < dest.ptr && src.ptr+n >= dest.ptr)
    {
        // move backward order
        foreach_reverse(i; 0..n)
        {
            dest[i] = src[i];
        }
    }
    return dest_;
}

void move(T)(ref T src, ref T dest)
{
    auto tmp = T.init;
    memmove(&dest, &src, T.sizeof);
    memmove(&src, &tmp, T.sizeof);
}