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        The header file 'boost/algorithm/cxx11/one_of.hpp' contains four variants
        of a single algorithm, one_of.
        The algorithm tests the elements of a sequence and returns true if exactly
        one of the elements in the sequence has a particular property.
      
        The routine one_of takes
        a sequence and a predicate. It will return true if the predicate returns
        true for one element in the sequence.
      
        The routine one_of_equal
        takes a sequence and a value. It will return true if one element in the sequence
        compares equal to the passed in value.
      
Both routines come in two forms; the first one takes two iterators to define the range. The second form takes a single range parameter, and uses Boost.Range to traverse it.
        The function one_of returns
        true if the predicate returns true for one item in the sequence. There are
        two versions; one takes two iterators, and the other takes a range.
      
namespace boost { namespace algorithm { template<typename InputIterator, typename Predicate> bool one_of ( InputIterator first, InputIterator last, Predicate p ); template<typename Range, typename Predicate> bool one_of ( const Range &r, Predicate p ); }}
        The function one_of_equal
        is similar to one_of, but
        instead of taking a predicate to test the elements of the sequence, it takes
        a value to compare against.
      
namespace boost { namespace algorithm { template<typename InputIterator, typename V> bool one_of_equal ( InputIterator first, InputIterator last, V const &val ); template<typename Range, typename V> bool one_of_equal ( const Range &r, V const &val ); }}
        Given the container c containing
        { 0, 1,
        2, 3, 14, 15 },
        then
bool isOdd ( int i ) { return i % 2 == 1; } bool lessThan10 ( int i ) { return i < 10; } using boost::algorithm; one_of ( c, isOdd ) --> false one_of ( c.begin (), c.end (), lessThan10 ) --> false one_of ( c.begin () + 3, c.end (), lessThan10 ) --> true one_of ( c.end (), c.end (), isOdd ) --> false // empty range one_of_equal ( c, 3 ) --> true one_of_equal ( c.begin (), c.begin () + 3, 3 ) --> false one_of_equal ( c.begin (), c.begin (), 99 ) --> false // empty range
        one_of and one_of_equal work on all iterators except
        output iterators.
      
        All of the variants of one_of
        and one_of_equal run in
        O(N) (linear) time; that is, they compare against each
        element in the list once. If more than one of the elements in the sequence
        satisfy the condition, then algorithm will return false immediately, without
        examining the remaining members of the sequence.
      
        All of the variants of one_of
        and one_of_equal take their
        parameters by value or const reference, and do not depend upon any global
        state. Therefore, all the routines in this file provide the strong exception
        guarantee.
      
one_of and one_of_equal both return false for
            empty ranges, no matter what is passed to test against.
          one_of_equal
            is a template parameter, rather than deduced from the first parameter
            (std::iterator_traits<InputIterator>::value_type) because that allows more
            flexibility for callers, and takes advantage of built-in comparisons
            for the type that is pointed to by the iterator. The function is defined
            to return true if, for one element in the sequence, the expression *iter == val
            evaluates to true (where iter
            is an iterator to each element in the sequence)