AlpakaInterface/interface/alpakastdAlgorithm.h

0001 #ifndef HeterogeneousCore_AlpakaInterface_interface_alpakastdAlgorithm_h
0002 #define HeterogeneousCore_AlpakaInterface_interface_alpakastdAlgorithm_h
0003
0004 #include <algorithm>
0005 #include <functional>
0006 #include <utility>
0007
0008 #include <alpaka/alpaka.hpp>
0009
0010 // reimplementation of std algorithms able to compile with Alpaka,
0011 // mostly by declaring them constexpr (until C++20, which will make it
0012 // constexpr by default. TODO: drop when moving to C++20)
0013
0014 namespace alpaka_std {
0015
0016   template <typename RandomIt, typename T, typename Compare = std::less<T>>
0017   ALPAKA_FN_HOST_ACC constexpr RandomIt upper_bound(RandomIt first, RandomIt last, const T &value, Compare comp = {}) {
0018     auto count = last - first;
0019
0020     while (count > 0) {
0021       auto it = first;
0022       auto step = count / 2;
0023       it += step;
0024       if (!comp(value, *it)) {
0025         first = ++it;
0026         count -= step + 1;
0027       } else {
0028         count = step;
0029       }
0030     }
0031     return first;
0032   }
0033
0034 }  // namespace alpaka_std
0035
0036 #endif  // HeterogeneousCore_AlpakaInterface_interface_alpakastdAlgorithm_h