boost::algorithm::one_of
// In header: <boost/algorithm/cxx11/one_of.hpp> template<typename Range, typename Predicate> BOOST_CXX14_CONSTEXPR bool one_of(const Range & r, Predicate p);
Parameters:
r
The input range
p
A predicate for testing the elements of the range
Returns:
true if the predicate 'p' is true for exactly one item in the range.