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 <algorithm> // for std::find and std::find_if
16 #include <boost/algorithm/cxx11/none_of.hpp>
17
18 #include <boost/range/begin.hpp>
19 #include <boost/range/end.hpp>
20
21 namespace boost { namespace algorithm {
22
23 /// \fn one_of ( InputIterator first, InputIterator last, Predicate p )
24 /// \return true if the predicate 'p' is true for exactly one item in [first, last).
25 ///
26 /// \param first The start of the input sequence
27 /// \param last One past the end of the input sequence
28 /// \param p A predicate for testing the elements of the sequence
29 ///
30 template<typename InputIterator, typename Predicate>
one_of(InputIterator first,InputIterator last,Predicate p)31 bool one_of ( InputIterator first, InputIterator last, Predicate p )
32 {
33 InputIterator i = std::find_if (first, last, p);
34 if (i == last)
35 return false; // Didn't occur at all
36 return boost::algorithm::none_of (++i, last, p);
37 }
38
39 /// \fn one_of ( const Range &r, Predicate p )
40 /// \return true if the predicate 'p' is true for exactly one item in the range.
41 ///
42 /// \param r The input range
43 /// \param p A predicate for testing the elements of the range
44 ///
45 template<typename Range, typename Predicate>
one_of(const Range & r,Predicate p)46 bool one_of ( const Range &r, Predicate p )
47 {
48 return boost::algorithm::one_of ( boost::begin (r), boost::end (r), p );
49 }
50
51
52 /// \fn one_of_equal ( InputIterator first, InputIterator last, const V &val )
53 /// \return true if the value 'val' exists only once in [first, last).
54 ///
55 /// \param first The start of the input sequence
56 /// \param last One past the end of the input sequence
57 /// \param val A value to compare against
58 ///
59 template<typename InputIterator, typename V>
one_of_equal(InputIterator first,InputIterator last,const V & val)60 bool one_of_equal ( InputIterator first, InputIterator last, const V &val )
61 {
62 InputIterator i = std::find (first, last, val); // find first occurrence of 'val'
63 if (i == last)
64 return false; // Didn't occur at all
65 return boost::algorithm::none_of_equal (++i, last, val);
66 }
67
68 /// \fn one_of_equal ( const Range &r, const V &val )
69 /// \return true if the value 'val' exists only once in the range.
70 ///
71 /// \param r The input range
72 /// \param val A value to compare against
73 ///
74 template<typename Range, typename V>
one_of_equal(const Range & r,const V & val)75 bool one_of_equal ( const Range &r, const V &val )
76 {
77 return boost::algorithm::one_of_equal ( boost::begin (r), boost::end (r), val );
78 }
79
80 }} // namespace boost and algorithm
81
82 #endif // BOOST_ALGORITHM_ALL_HPP
83