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-no-concepts
11 // UNSUPPORTED: libcpp-has-no-incomplete-ranges
12 
13 // transform_view() requires std::default_initializable<V> &&
14 //                           std::default_initializable<F> = default;
15 
16 #include <ranges>
17 
18 #include <cassert>
19 #include <type_traits>
20 
21 constexpr int buff[] = {1, 2, 3};
22 
23 struct DefaultConstructibleView : std::ranges::view_base {
24   constexpr DefaultConstructibleView() : begin_(buff), end_(buff + 3) { }
25   constexpr int const* begin() const { return begin_; }
26   constexpr int const* end() const { return end_; }
27 private:
28   int const* begin_;
29   int const* end_;
30 };
31 
32 struct DefaultConstructibleFunction {
33   int state_;
34   constexpr DefaultConstructibleFunction() : state_(100) { }
35   constexpr int operator()(int i) const { return i + state_; }
36 };
37 
38 struct NoDefaultView : std::ranges::view_base {
39   NoDefaultView() = delete;
40   int* begin() const;
41   int* end() const;
42 };
43 
44 struct NoDefaultFunction {
45   NoDefaultFunction() = delete;
46   constexpr int operator()(int i) const;
47 };
48 
49 constexpr bool test() {
50   {
51     std::ranges::transform_view<DefaultConstructibleView, DefaultConstructibleFunction> view;
52     assert(view.size() == 3);
53     assert(view[0] == 101);
54     assert(view[1] == 102);
55     assert(view[2] == 103);
56   }
57 
58   {
59     std::ranges::transform_view<DefaultConstructibleView, DefaultConstructibleFunction> view = {};
60     assert(view.size() == 3);
61     assert(view[0] == 101);
62     assert(view[1] == 102);
63     assert(view[2] == 103);
64   }
65 
66   static_assert(!std::is_default_constructible_v<std::ranges::transform_view<NoDefaultView,            DefaultConstructibleFunction>>);
67   static_assert(!std::is_default_constructible_v<std::ranges::transform_view<DefaultConstructibleView, NoDefaultFunction>>);
68   static_assert(!std::is_default_constructible_v<std::ranges::transform_view<NoDefaultView,            NoDefaultFunction>>);
69 
70   return true;
71 }
72 
73 int main(int, char**) {
74   test();
75   static_assert(test());
76 
77   return 0;
78 }
79