1 //===----------------------------------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 // UNSUPPORTED: c++03, c++11, c++14, c++17
10 // UNSUPPORTED: libcpp-has-no-incomplete-ranges
11 
12 // template <input_range Range>
13 //   requires constructible_from<View, views::all_t<Range>> &&
14 //             constructible_from<Pattern, single_view<range_value_t<Range>>>
15 // constexpr lazy_split_view(Range&& r, range_value_t<Range> e);
16 
17 #include <ranges>
18 
19 #include <cassert>
20 #include <string>
21 #include <string_view>
22 #include <type_traits>
23 #include <utility>
24 #include "types.h"
25 
26 struct ElementWithCounting {
27   int* times_copied = nullptr;
28   int* times_moved = nullptr;
29 
30   constexpr ElementWithCounting(int& copies_ctr, int& moves_ctr) : times_copied(&copies_ctr), times_moved(&moves_ctr) {}
31 
32   constexpr ElementWithCounting(const ElementWithCounting& rhs)
33       : times_copied(rhs.times_copied)
34       , times_moved(rhs.times_moved) {
35     ++(*times_copied);
36   }
37   constexpr ElementWithCounting(ElementWithCounting&& rhs)
38       : times_copied(rhs.times_copied)
39       , times_moved(rhs.times_moved) {
40     ++(*times_moved);
41   }
42 
43   constexpr bool operator==(const ElementWithCounting&) const { return true; }
44 };
45 
46 struct RangeWithCounting {
47   using value_type = ElementWithCounting;
48 
49   int* times_copied = nullptr;
50   int* times_moved = nullptr;
51 
52   constexpr RangeWithCounting(int& copies_ctr, int& moves_ctr) : times_copied(&copies_ctr), times_moved(&moves_ctr) {}
53 
54   constexpr RangeWithCounting(const RangeWithCounting& rhs)
55     : times_copied(rhs.times_copied)
56     , times_moved(rhs.times_moved) {
57     ++(*times_copied);
58   }
59   constexpr RangeWithCounting(RangeWithCounting&& rhs)
60     : times_copied(rhs.times_copied)
61     , times_moved(rhs.times_moved) {
62     ++(*times_moved);
63   }
64 
65   constexpr const ElementWithCounting* begin() const { return nullptr; }
66   constexpr const ElementWithCounting* end() const { return nullptr; }
67 
68   constexpr RangeWithCounting& operator=(const RangeWithCounting&) = default;
69   constexpr RangeWithCounting& operator=(RangeWithCounting&&) = default;
70   constexpr bool operator==(const RangeWithCounting&) const { return true; }
71 };
72 static_assert( std::ranges::forward_range<RangeWithCounting>);
73 static_assert(!std::ranges::view<RangeWithCounting>);
74 
75 struct StrView : std::ranges::view_base {
76   std::string_view buffer_;
77   constexpr explicit StrView() = default;
78   constexpr StrView(const char* ptr) : buffer_(ptr) {}
79   // Intentionally don't forward to range constructor for std::string_view since
80   // this test needs to work on C++20 as well and the range constructor is only for
81   // C++23 and later.
82   template <std::ranges::range R>
83   constexpr StrView(R&& r) : buffer_(r.begin(), r.end()) {}
84   constexpr const char* begin() const { return buffer_.begin(); }
85   constexpr const char* end() const { return buffer_.end(); }
86   constexpr bool operator==(const StrView& rhs) const { return buffer_ == rhs.buffer_; }
87 };
88 static_assert( std::ranges::random_access_range<StrView>);
89 static_assert( std::ranges::view<StrView>);
90 static_assert( std::is_copy_constructible_v<StrView>);
91 
92 constexpr bool test() {
93   {
94     using V = std::ranges::lazy_split_view<StrView, StrView>;
95 
96     // Calling the constructor with `(std::string, range_value_t)`.
97     {
98       std::string input;
99       V v(input, ' ');
100       assert(v.base() == input);
101     }
102 
103     // Calling the constructor with `(StrView, range_value_t)`.
104     {
105       StrView input("abc def");
106       V v(input, ' ');
107       assert(v.base() == input);
108     }
109 
110     struct Empty {};
111     static_assert(!std::is_constructible_v<V, Empty, std::string_view>);
112     static_assert(!std::is_constructible_v<V, std::string_view, Empty>);
113   }
114 
115   // Make sure the arguments are moved, not copied.
116   {
117     using Range = RangeWithCounting;
118     using Element = ElementWithCounting;
119     using Pattern = std::ranges::single_view<Element>;
120 
121     // Arguments are lvalues.
122     {
123       using View = std::ranges::ref_view<Range>;
124 
125       int range_copied = 0, range_moved = 0, element_copied = 0, element_moved = 0;
126       Range range(range_copied, range_moved);
127       Element element(element_copied, element_moved);
128 
129       std::ranges::lazy_split_view<View, Pattern> v(range, element);
130       assert(range_copied == 0); // `ref_view` does neither copy...
131       assert(range_moved == 0); // ...nor move the element.
132       assert(element_copied == 1); // The element is copied into the argument...
133       assert(element_moved == 1); // ...and moved into the member variable.
134     }
135 
136     // Arguments are rvalues.
137     {
138       using View = std::ranges::owning_view<Range>;
139 
140       int range_copied = 0, range_moved = 0, element_copied = 0, element_moved = 0;
141       std::ranges::lazy_split_view<View, Pattern> v(
142           Range(range_copied, range_moved), Element(element_copied, element_moved));
143       assert(range_copied == 0);
144       assert(range_moved == 1); // `owning_view` moves the given argument.
145       assert(element_copied == 0);
146       assert(element_moved == 1);
147     }
148   }
149 
150   return true;
151 }
152 
153 int main(int, char**) {
154   test();
155   static_assert(test());
156 
157   return 0;
158 }
159