Function ShuffleRange

test/common/gtest/gtest.cpp:718–735

// shuffle to the end of the vector.
template <typename E>
void ShuffleRange(internal::Random* random, int begin, int end,
                  std::vector<E>* v) {
  const int size = static_cast<int>(v->size());
  GTEST_CHECK_(0 <= begin && begin <= size)
      << "Invalid shuffle range start " << begin << ": must be in range [0, "
      << size << "].";
  GTEST_CHECK_(begin <= end && end <= size)
      << "Invalid shuffle range finish " << end << ": must be in range ["
      << begin << ", " << size << "].";

  // Fisher-Yates shuffle, from
  // http://en.wikipedia.org/wiki/Fisher-Yates_shuffle
  for (int range_width = end - begin; range_width >= 2; range_width--) {
    const int last_in_range = begin + range_width - 1;
    const int selected = begin + random->Generate(range_width);
    std::swap((*v)[selected], (*v)[last_in_range]);
  }
}

// Performs an in-place shuffle of the vector's elements.
template <typename E>