1/*
2 Copyright (c) Marshall Clow 2008-2012.
3
4 Distributed under the Boost Software License, Version 1.0. (See accompanying
5 file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
6*/
7
8/// \file one_of.hpp
9/// \brief Test ranges to see if only one element matches a value or predicate.
10/// \author Marshall Clow
11
12#ifndef BOOST_ALGORITHM_ONE_OF_HPP
13#define BOOST_ALGORITHM_ONE_OF_HPP
14
15#include <boost/config.hpp>
16#include <boost/range/begin.hpp>
17#include <boost/range/end.hpp>
18
19#include <boost/algorithm/cxx11/none_of.hpp>
20
21
22namespace boost { namespace algorithm {
23
24/// \fn one_of ( InputIterator first, InputIterator last, Predicate p )
25/// \return true if the predicate 'p' is true for exactly one item in [first, last).
26///
27/// \param first The start of the input sequence
28/// \param last One past the end of the input sequence
29/// \param p A predicate for testing the elements of the sequence
30///
31template<typename InputIterator, typename Predicate>
32BOOST_CXX14_CONSTEXPR bool one_of ( InputIterator first, InputIterator last, Predicate p )
33{
34// find_if
35 for (; first != last; ++first)
36 if (p(*first))
37 break;
38
39 if (first == last)
40 return false; // Didn't occur at all
41 return boost::algorithm::none_of (++first, last, p);
42}
43
44/// \fn one_of ( const Range &r, Predicate p )
45/// \return true if the predicate 'p' is true for exactly one item in the range.
46///
47/// \param r The input range
48/// \param p A predicate for testing the elements of the range
49///
50template<typename Range, typename Predicate>
51BOOST_CXX14_CONSTEXPR bool one_of ( const Range &r, Predicate p )
52{
53 return boost::algorithm::one_of ( boost::begin (r), boost::end (r), p );
54}
55
56
57/// \fn one_of_equal ( InputIterator first, InputIterator last, const V &val )
58/// \return true if the value 'val' exists only once in [first, last).
59///
60/// \param first The start of the input sequence
61/// \param last One past the end of the input sequence
62/// \param val A value to compare against
63///
64template<typename InputIterator, typename V>
65BOOST_CXX14_CONSTEXPR bool one_of_equal ( InputIterator first, InputIterator last, const V &val )
66{
67// find
68 for (; first != last; ++first)
69 if (*first == val)
70 break;
71
72 if (first == last)
73 return false; // Didn't occur at all
74 return boost::algorithm::none_of_equal (++first, last, val);
75}
76
77/// \fn one_of_equal ( const Range &r, const V &val )
78/// \return true if the value 'val' exists only once in the range.
79///
80/// \param r The input range
81/// \param val A value to compare against
82///
83template<typename Range, typename V>
84BOOST_CXX14_CONSTEXPR bool one_of_equal ( const Range &r, const V &val )
85{
86 return boost::algorithm::one_of_equal ( boost::begin (r), boost::end (r), val );
87}
88
89}} // namespace boost and algorithm
90
91#endif // BOOST_ALGORITHM_ALL_HPP
92

source code of boost/libs/algorithm/include/boost/algorithm/cxx11/one_of.hpp