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minmax_element.hpp
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1 // Range v3 library
3 //
4 // Copyright Eric Niebler 2014-present
5 //
6 // Use, modification and distribution is subject to the
7 // Boost Software License, Version 1.0. (See accompanying
8 // file LICENSE_1_0.txt or copy at
9 // http://www.boost.org/LICENSE_1_0.txt)
10 //
11 // Project home: https://github.com/ericniebler/range-v3
12 //
13 // Implementation based on the code in libc++
14 // http://http://libcxx.llvm.org/
15 
16 #ifndef RANGES_V3_ALGORITHM_MINMAX_ELEMENT_HPP
17 #define RANGES_V3_ALGORITHM_MINMAX_ELEMENT_HPP
18 
19 #include <range/v3/range_fwd.hpp>
20 
21 #include <range/v3/algorithm/result_types.hpp>
31 #include <range/v3/utility/static_const.hpp>
32 
33 #include <range/v3/detail/prologue.hpp>
34 
35 namespace ranges
36 {
39  template<typename I>
40  using minmax_element_result = detail::min_max_result<I, I>;
41 
42  RANGES_FUNC_BEGIN(minmax_element)
43 
44 
45  template(typename I, typename S, typename C = less, typename P = identity)(
46  requires forward_iterator<I> AND sentinel_for<S, I> AND
47  indirect_strict_weak_order<C, projected<I, P>>)
48  constexpr minmax_element_result<I> //
49  RANGES_FUNC(minmax_element)(I first, S last, C pred = C{}, P proj = P{}) //
50  {
51  minmax_element_result<I> result{first, first};
52  if(first == last || ++first == last)
53  return result;
54  if(invoke(pred, invoke(proj, *first), invoke(proj, *result.min)))
55  result.min = first;
56  else
57  result.max = first;
58  while(++first != last)
59  {
60  I tmp = first;
61  if(++first == last)
62  {
63  if(invoke(pred, invoke(proj, *tmp), invoke(proj, *result.min)))
64  result.min = tmp;
65  else if(!invoke(pred, invoke(proj, *tmp), invoke(proj, *result.max)))
66  result.max = tmp;
67  break;
68  }
69  else
70  {
71  if(invoke(pred, invoke(proj, *first), invoke(proj, *tmp)))
72  {
73  if(invoke(pred, invoke(proj, *first), invoke(proj, *result.min)))
74  result.min = first;
75  if(!invoke(pred, invoke(proj, *tmp), invoke(proj, *result.max)))
76  result.max = tmp;
77  }
78  else
79  {
80  if(invoke(pred, invoke(proj, *tmp), invoke(proj, *result.min)))
81  result.min = tmp;
82  if(!invoke(pred, invoke(proj, *first), invoke(proj, *result.max)))
83  result.max = first;
84  }
85  }
86  }
87  return result;
88  }
89 
91  template(typename Rng, typename C = less, typename P = identity)(
92  requires forward_range<Rng> AND
93  indirect_strict_weak_order<C, projected<iterator_t<Rng>, P>>)
94  constexpr minmax_element_result<borrowed_iterator_t<Rng>> //
95  RANGES_FUNC(minmax_element)(Rng && rng, C pred = C{}, P proj = P{}) //
96  {
97  return (*this)(begin(rng), end(rng), std::move(pred), std::move(proj));
98  }
99 
100  RANGES_FUNC_END(minmax_element)
101 
102  namespace cpp20
103  {
104  using ranges::minmax_element;
105  using ranges::minmax_element_result;
106  } // namespace cpp20
108 } // namespace ranges
109 
110 #include <range/v3/detail/epilogue.hpp>
111 
112 #endif
CPP_concept indirect_strict_weak_order
\concept indirect_strict_weak_order
Definition: concepts.hpp:689
typename Fn::template invoke< Args... > invoke
Evaluate the invocable Fn with the arguments Args.
Definition: meta.hpp:541
front< Pair > first
Retrieve the first element of the pair Pair.
Definition: meta.hpp:2251
bool_<(T::type::value< U::type::value)> less
A Boolean integral constant wrapper around true if T::type::value is less than U::type::value; false,...
Definition: meta.hpp:255