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