gcc complex constant folding

Question

It seems that gcc has some limitation on complex constant folding. Here is an example:

static inline unsigned int DJBHash(const char *str)
{
   int i;
   uns         


        

Answer 1

Perhaps C++ TMP might be able to do it. I'm not sure though.

It is possible if you don't mind using variadic character literal lists instead of string literals:

#include 
#include 

template
struct DJBhash_helper
     : std::integral_constant {};

template
struct DJBhash_helper
     : DJBhash_helper<(acc << 5) + acc + head, tail...> {};

template
struct DJBhash
     : DJBhash_helper<5381, str...> {};

int main()
{
    std::cout << DJBhash<'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
                         '0', '1', '2', '3', '4', '5', '6', '7'>::value << '\n';
}

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