1 //===----------------------------------------------------------------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is dual licensed under the MIT and the University of Illinois Open
6 // Source Licenses. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 // UNSUPPORTED: c++98, c++03, c++11, c++14, c++17
10
11 // <span>
12
13 // constexpr reverse_iterator rbegin() const noexcept;
14 // constexpr const_reverse_iterator crbegin() const noexcept;
15
16 #include <span>
17 #include <cassert>
18 #include <string>
19
20 #include "test_macros.h"
21
22 template <class Span>
testConstexprSpan(Span s)23 constexpr bool testConstexprSpan(Span s)
24 {
25 bool ret = true;
26 typename Span::reverse_iterator b = s. rbegin();
27 typename Span::const_reverse_iterator cb = s.crbegin();
28 if (s.empty())
29 {
30 ret = ret && ( b == s.rend());
31 ret = ret && (cb == s.crend());
32 }
33 else
34 {
35 const typename Span::index_type last = s.size() - 1;
36 ret = ret && ( *b == s[last]);
37 ret = ret && ( &*b == &s[last]);
38 ret = ret && ( *cb == s[last]);
39 ret = ret && (&*cb == &s[last]);
40 }
41 ret = ret && (b == cb);
42 return ret;
43 }
44
45
46 template <class Span>
testRuntimeSpan(Span s)47 void testRuntimeSpan(Span s)
48 {
49 typename Span::reverse_iterator b = s. rbegin();
50 typename Span::const_reverse_iterator cb = s.crbegin();
51 if (s.empty())
52 {
53 assert( b == s.rend());
54 assert(cb == s.crend());
55 }
56 else
57 {
58 const typename Span::index_type last = s.size() - 1;
59 assert( *b == s[last]);
60 assert( &*b == &s[last]);
61 assert( *cb == s[last]);
62 assert(&*cb == &s[last]);
63 }
64 assert(b == cb);
65 }
66
67
68 struct A{};
operator ==(A,A)69 bool operator==(A, A) {return true;}
70
71 constexpr int iArr1[] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
72 int iArr2[] = {10, 11, 12, 13, 14, 15, 16, 17, 18, 19};
73
74
main()75 int main()
76 {
77 static_assert(testConstexprSpan(std::span<int>()), "");
78 static_assert(testConstexprSpan(std::span<long>()), "");
79 static_assert(testConstexprSpan(std::span<double>()), "");
80 static_assert(testConstexprSpan(std::span<A>()), "");
81 static_assert(testConstexprSpan(std::span<std::string>()), "");
82
83 static_assert(testConstexprSpan(std::span<int, 0>()), "");
84 static_assert(testConstexprSpan(std::span<long, 0>()), "");
85 static_assert(testConstexprSpan(std::span<double, 0>()), "");
86 static_assert(testConstexprSpan(std::span<A, 0>()), "");
87 static_assert(testConstexprSpan(std::span<std::string, 0>()), "");
88
89 static_assert(testConstexprSpan(std::span<const int>(iArr1, 1)), "");
90 static_assert(testConstexprSpan(std::span<const int>(iArr1, 2)), "");
91 static_assert(testConstexprSpan(std::span<const int>(iArr1, 3)), "");
92 static_assert(testConstexprSpan(std::span<const int>(iArr1, 4)), "");
93 static_assert(testConstexprSpan(std::span<const int>(iArr1, 5)), "");
94
95
96 testRuntimeSpan(std::span<int> ());
97 testRuntimeSpan(std::span<long> ());
98 testRuntimeSpan(std::span<double> ());
99 testRuntimeSpan(std::span<A> ());
100 testRuntimeSpan(std::span<std::string>());
101
102 testRuntimeSpan(std::span<int, 0> ());
103 testRuntimeSpan(std::span<long, 0> ());
104 testRuntimeSpan(std::span<double, 0> ());
105 testRuntimeSpan(std::span<A, 0> ());
106 testRuntimeSpan(std::span<std::string, 0>());
107
108 testRuntimeSpan(std::span<int>(iArr2, 1));
109 testRuntimeSpan(std::span<int>(iArr2, 2));
110 testRuntimeSpan(std::span<int>(iArr2, 3));
111 testRuntimeSpan(std::span<int>(iArr2, 4));
112 testRuntimeSpan(std::span<int>(iArr2, 5));
113
114 std::string s;
115 testRuntimeSpan(std::span<std::string>(&s, static_cast<std::ptrdiff_t>(0)));
116 testRuntimeSpan(std::span<std::string>(&s, 1));
117 }
118