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
21namespace 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///
30template<typename InputIterator, typename Predicate>
31bool 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///
45template<typename Range, typename Predicate>
46bool 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///
59template<typename InputIterator, typename V>
60bool 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///
74template<typename Range, typename V>
75bool 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