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 // UNSUPPORTED: c++03, c++11, c++14, c++17
9 
10 // <span>
11 
12 // constexpr       iterator  end() const noexcept;
13 // constexpr const_iterator cend() const noexcept;
14 
15 #include <span>
16 #include <cassert>
17 #include <string>
18 
19 #include "test_macros.h"
20 
21 template <class Span>
22 constexpr bool testConstexprSpan(Span s)
23 {
24     bool ret = true;
25     typename Span::iterator e = s.end();
26     if (s.empty())
27     {
28         ret = ret &&  (e == s.begin());
29     }
30     else
31     {
32         typename Span::const_pointer last = &*(s.begin() + s.size() - 1);
33         ret = ret &&  (e != s.begin());
34         ret = ret &&  (&*( e-1) == last);
35     }
36 
37     ret = ret &&  (static_cast<size_t>(e - s.begin()) == s.size());
38     return ret;
39 }
40 
41 template <class Span>
42 void testRuntimeSpan(Span s)
43 {
44     typename Span::iterator e = s.end();
45     if (s.empty())
46     {
47         assert(e == s.begin());
48     }
49     else
50     {
51         typename Span::const_pointer last = &*(s.begin() + s.size() - 1);
52         assert(e != s.begin());
53         assert(&*( e-1) == last);
54     }
55 
56     assert(static_cast<size_t>(e - s.begin()) == s.size());
57 }
58 
59 
60 struct A{};
61 bool operator==(A, A) {return true;}
62 
63 constexpr int iArr1[] = { 0,  1,  2,  3,  4,  5,  6,  7,  8,  9};
64           int iArr2[] = {10, 11, 12, 13, 14, 15, 16, 17, 18, 19};
65 
66 
67 int main(int, char**)
68 {
69     static_assert(testConstexprSpan(std::span<int>()),            "");
70     static_assert(testConstexprSpan(std::span<long>()),           "");
71     static_assert(testConstexprSpan(std::span<double>()),         "");
72     static_assert(testConstexprSpan(std::span<A>()),              "");
73     static_assert(testConstexprSpan(std::span<std::string>()),    "");
74 
75     static_assert(testConstexprSpan(std::span<int, 0>()),         "");
76     static_assert(testConstexprSpan(std::span<long, 0>()),        "");
77     static_assert(testConstexprSpan(std::span<double, 0>()),      "");
78     static_assert(testConstexprSpan(std::span<A, 0>()),           "");
79     static_assert(testConstexprSpan(std::span<std::string, 0>()), "");
80 
81     static_assert(testConstexprSpan(std::span<const int>(iArr1, 1)),    "");
82     static_assert(testConstexprSpan(std::span<const int>(iArr1, 2)),    "");
83     static_assert(testConstexprSpan(std::span<const int>(iArr1, 3)),    "");
84     static_assert(testConstexprSpan(std::span<const int>(iArr1, 4)),    "");
85     static_assert(testConstexprSpan(std::span<const int>(iArr1, 5)),    "");
86 
87 
88     testRuntimeSpan(std::span<int>        ());
89     testRuntimeSpan(std::span<long>       ());
90     testRuntimeSpan(std::span<double>     ());
91     testRuntimeSpan(std::span<A>          ());
92     testRuntimeSpan(std::span<std::string>());
93 
94     testRuntimeSpan(std::span<int, 0>        ());
95     testRuntimeSpan(std::span<long, 0>       ());
96     testRuntimeSpan(std::span<double, 0>     ());
97     testRuntimeSpan(std::span<A, 0>          ());
98     testRuntimeSpan(std::span<std::string, 0>());
99 
100     testRuntimeSpan(std::span<int>(iArr2, 1));
101     testRuntimeSpan(std::span<int>(iArr2, 2));
102     testRuntimeSpan(std::span<int>(iArr2, 3));
103     testRuntimeSpan(std::span<int>(iArr2, 4));
104     testRuntimeSpan(std::span<int>(iArr2, 5));
105 
106     std::string s;
107     testRuntimeSpan(std::span<std::string>(&s, (std::size_t) 0));
108     testRuntimeSpan(std::span<std::string>(&s, 1));
109 
110   return 0;
111 }
112