shuffle.hpp

Go to the documentation of this file.

/*
Copyright© 2014 Akihiro Nishimura

This software is released under the MIT License.
http://opensource.org/licenses/mit-license.php
*/

#ifndef SIG_UTIL_SHUFFLE_HPP
#define SIG_UTIL_SHUFFLE_HPP

#include "../sigutil.hpp"
#include "../tools/random.hpp"


namespace sig
{

template <class C>
void shuffle(C& container)
{
    static SimpleRandom<double> myrand(0.0, 1.0, false);

    std::random_shuffle(std::begin(container), std::end(container), [&](std::ptrdiff_t max){ return static_cast<std::ptrdiff_t>(myrand() * max); });
}


namespace impl
{

template <class C>
void shuffle_impl(uint loop, C const& seq){}

template <class C, class It, class... Its>
void shuffle_impl(uint loop, C const& seq, It iter, Its... iters)
{
    auto ori_iter = iter;
    std::unordered_map<uint, typename It::value_type> map;

    for (uint i=0; i<loop; ++i, ++iter){
        map[seq[i]] = *iter;
    }
    for (uint i = 0; i < loop; ++i, ++ori_iter){
        *ori_iter = map[i];
    }

    shuffle_impl(loop, seq, iters...);
}
}   //impl


template <class... Cs>
void shuffle(Cs&... containers)
{
    uint size = min(containers.size()...);
    auto rseq = make_unique_numbers(size, 0, size - 1, false);
        
    impl::shuffle_impl(size, rseq, std::begin(containers)...);
}

}
#endif