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partition_point.hpp
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1
2// Range v3 library
3//
4// Copyright Eric Niebler 2014-present
5// Copyright Casey Carter 2016
6//
7// Use, modification and distribution is subject to the
8// Boost Software License, Version 1.0. (See accompanying
9// file LICENSE_1_0.txt or copy at
10// http://www.boost.org/LICENSE_1_0.txt)
11//
12// Project home: https://github.com/ericniebler/range-v3
13//
14//===-------------------------- algorithm ---------------------------------===//
15//
16// The LLVM Compiler Infrastructure
17//
18// This file is dual licensed under the MIT and the University of Illinois Open
19// Source Licenses. See LICENSE.TXT for details.
20//
21//===----------------------------------------------------------------------===//
22#ifndef RANGES_V3_ALGORITHM_PARTITION_POINT_HPP
23#define RANGES_V3_ALGORITHM_PARTITION_POINT_HPP
24
25#include <meta/meta.hpp>
26
28
39#include <range/v3/utility/static_const.hpp>
40
41#include <range/v3/detail/prologue.hpp>
42
43namespace ranges
44{
47
48 RANGES_FUNC_BEGIN(partition_point)
49
50
51 template(typename I, typename S, typename C, typename P = identity)(
52 requires forward_iterator<I> AND sentinel_for<S, I> AND
53 indirect_unary_predicate<C, projected<I, P>>)
54 constexpr I RANGES_FUNC(partition_point)(I first, S last, C pred, P proj = P{})
55 {
56 if(RANGES_CONSTEXPR_IF(sized_sentinel_for<S, I>))
57 {
58 auto len = distance(first, std::move(last));
59 return aux::partition_point_n(
60 std::move(first), len, std::move(pred), std::move(proj));
61 }
62
63 // Probe exponentially for either last-of-range or an iterator
64 // that is past the partition point (i.e., does not satisfy pred).
65 auto len = iter_difference_t<I>{1};
66 while(true)
67 {
68 auto mid = first;
69 auto d = advance(mid, len, last);
70 if(mid == last || !invoke(pred, invoke(proj, *mid)))
71 {
72 len -= d;
73 return aux::partition_point_n(
74 std::move(first), len, ranges::ref(pred), ranges::ref(proj));
75 }
76 first = std::move(mid);
77 len *= 2;
78 }
79 }
80
82 template(typename Rng, typename C, typename P = identity)(
83 requires forward_range<Rng> AND
84 indirect_unary_predicate<C, projected<iterator_t<Rng>, P>>)
85 constexpr borrowed_iterator_t<Rng> //
86 RANGES_FUNC(partition_point)(Rng && rng, C pred, P proj = P{}) //
87 {
88 if(RANGES_CONSTEXPR_IF(sized_range<Rng>))
89 {
90 auto len = distance(rng);
91 return aux::partition_point_n(
92 begin(rng), len, std::move(pred), std::move(proj));
93 }
94 return (*this)(begin(rng), end(rng), std::move(pred), std::move(proj));
95 }
96
97 RANGES_FUNC_END(partition_point)
98
99 namespace cpp20
100 {
101 using ranges::partition_point;
102 }
104} // namespace ranges
105
106#include <range/v3/detail/epilogue.hpp>
107
108#endif
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
Tiny meta-programming library.