Visual Studio 14 CTP 3 : C++11 constexpr testing

vs14-ctp3-constexpr.cpp

// (1) In VS14 CTP3, implementation of constexpr is still partial.
// http://blogs.msdn.com/b/vcblog/archive/2014/06/11/c-11-14-feature-tables-for-visual-studio-14-ctp1.aspx
//
#include <stdio.h>
#include <stdint.h>


// (2) Straightforward FOURCC
constexpr uint32_t fourcc(const char* p) {
    return   (static_cast<uint32_t>(p[0]) << (8*0))
           | (static_cast<uint32_t>(p[1]) << (8*1))
           | (static_cast<uint32_t>(p[2]) << (8*2))
           | (static_cast<uint32_t>(p[3]) << (8*3));
}

void test_fourcc() {
    const uint32_t c = ('F' << 0) | ('O' << 8) | ('U' << 16) | ('R' << 24);

    switch(c) {
    default:                printf("c = ?\n");      break;
    case fourcc("FOUR"):    printf("c = four\n");   break;
    case fourcc("FIVE"):    printf("c = five\n");   break;
    }
}


// (3) VS14 CTP3 could not compile Clement JACOB's CRC32.
// http://stackoverflow.com/a/9842857/2132223


// (4) Jerry Coffin's constexpr hash function.
// http://stackoverflow.com/a/2112111/2132223
uint32_t constexpr const_hash0(const char* p, int i) {
    return p[i] == 0
        ? 5381
        : static_cast<uint32_t>(p[i]) + 33 * const_hash0(p, i+1)
    ;
}

uint32_t constexpr const_hash(const char* p) {
    return const_hash0(p, 0);
}

void test_hash() {
    enum : uint32_t {
        h = const_hash("ABCD"),
    };
    printf("h = %08x\n", h);
}


//
int main() {
    test_hash();
    test_fourcc();
}