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 // <string_view>
10 
11 // constexpr const_iterator begin() const;
12 
13 #include <string_view>
14 #include <cassert>
15 
16 #include "test_macros.h"
17 
18 template <class S>
19 void
20 test(S s)
21 {
22     const S& cs = s;
23     typename S::iterator b = s.begin();
24     typename S::const_iterator cb1 = cs.begin();
25     typename S::const_iterator cb2 = s.cbegin();
26     if (!s.empty())
27     {
28         assert(   *b ==  s[0]);
29         assert(  &*b == &s[0]);
30         assert( *cb1 ==  s[0]);
31         assert(&*cb1 == &s[0]);
32         assert( *cb2 ==  s[0]);
33         assert(&*cb2 == &s[0]);
34 
35     }
36     assert(  b == cb1);
37     assert(  b == cb2);
38     assert(cb1 == cb2);
39 }
40 
41 
42 int main(int, char**)
43 {
44     typedef std::string_view    string_view;
45 #if defined(__cpp_lib_char8_t) && __cpp_lib_char8_t >= 201811L
46     typedef std::u8string_view  u8string_view;
47 #endif
48     typedef std::u16string_view u16string_view;
49     typedef std::u32string_view u32string_view;
50     typedef std::wstring_view   wstring_view;
51 
52     test(string_view   ());
53     test(u16string_view());
54     test(u32string_view());
55     test(wstring_view  ());
56     test(string_view   ( "123"));
57     test(wstring_view  (L"123"));
58 #if defined(__cpp_lib_char8_t) && __cpp_lib_char8_t >= 201811L
59     test(u8string_view{u8"123"});
60 #endif
61 #if TEST_STD_VER >= 11
62     test(u16string_view{u"123"});
63     test(u32string_view{U"123"});
64 #endif
65 
66 #if TEST_STD_VER > 11
67     {
68     constexpr string_view       sv { "123", 3 };
69 #if defined(__cpp_lib_char8_t) && __cpp_lib_char8_t >= 201811L
70     constexpr u8string_view u8sv  {u8"123", 3 };
71 #endif
72     constexpr u16string_view u16sv {u"123", 3 };
73     constexpr u32string_view u32sv {U"123", 3 };
74     constexpr wstring_view     wsv {L"123", 3 };
75 
76     static_assert (    *sv.begin() ==    sv[0], "" );
77 #if defined(__cpp_lib_char8_t) && __cpp_lib_char8_t >= 201811L
78     static_assert (  *u8sv.begin() ==  u8sv[0], "" );
79 #endif
80     static_assert ( *u16sv.begin() == u16sv[0], "" );
81     static_assert ( *u32sv.begin() == u32sv[0], "" );
82     static_assert (   *wsv.begin() ==   wsv[0], "" );
83 
84     static_assert (    *sv.cbegin() ==    sv[0], "" );
85 #if defined(__cpp_lib_char8_t) && __cpp_lib_char8_t >= 201811L
86     static_assert (  *u8sv.cbegin() ==  u8sv[0], "" );
87 #endif
88     static_assert ( *u16sv.cbegin() == u16sv[0], "" );
89     static_assert ( *u32sv.cbegin() == u32sv[0], "" );
90     static_assert (   *wsv.cbegin() ==   wsv[0], "" );
91     }
92 #endif
93 
94   return 0;
95 }
96