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: !stdlib=libc++ && (c++03 || c++11 || c++14)
10 
11 // <string_view>
12 
13 // constexpr const _CharT& back();
14 
15 #include <string_view>
16 #include <cassert>
17 
18 #include "test_macros.h"
19 
20 template <typename CharT>
21 bool test ( const CharT *s, size_t len ) {
22     typedef std::basic_string_view<CharT> SV;
23     SV sv ( s, len );
24     ASSERT_SAME_TYPE(decltype(sv.front()), typename SV::const_reference);
25     LIBCPP_ASSERT_NOEXCEPT(   sv.front());
26     assert ( sv.length() == len );
27     assert ( sv.front() == s[0] );
28     return &sv.front() == s;
29     }
30 
31 int main(int, char**) {
32     assert ( test ( "ABCDE", 5 ));
33     assert ( test ( "a", 1 ));
34 
35     assert ( test ( L"ABCDE", 5 ));
36     assert ( test ( L"a", 1 ));
37 
38 #if TEST_STD_VER >= 11
39     assert ( test ( u"ABCDE", 5 ));
40     assert ( test ( u"a", 1 ));
41 
42     assert ( test ( U"ABCDE", 5 ));
43     assert ( test ( U"a", 1 ));
44 #endif
45 
46 #if TEST_STD_VER >= 11
47     {
48     constexpr std::basic_string_view<char> sv ( "ABC", 2 );
49     static_assert ( sv.length() ==  2,  "" );
50     static_assert ( sv.front()  == 'A', "" );
51     }
52 #endif
53 
54   return 0;
55 }
56