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 
10 // <string_view>
11 
12 // void remove_prefix(size_type _n)
13 
14 #include <string_view>
15 #include <cassert>
16 
17 #include "test_macros.h"
18 
19 template<typename CharT>
20 void test ( const CharT *s, size_t len ) {
21     typedef std::basic_string_view<CharT> SV;
22     {
23     SV sv1 ( s );
24     assert ( sv1.size() == len );
25     assert ( sv1.data() == s );
26 
27     if ( len > 0 ) {
28         sv1.remove_prefix ( 1 );
29         assert ( sv1.size() == (len - 1));
30         assert ( sv1.data() == (s + 1));
31         sv1.remove_prefix ( len - 1 );
32     }
33 
34     assert ( sv1.size() == 0 );
35     sv1.remove_prefix ( 0 );
36     assert ( sv1.size() == 0 );
37     }
38 }
39 
40 #if TEST_STD_VER > 11
41 constexpr size_t test_ce ( size_t n, size_t k ) {
42     typedef std::basic_string_view<char> SV;
43     SV sv1{ "ABCDEFGHIJKL", n };
44     sv1.remove_prefix ( k );
45     return sv1.size();
46 }
47 #endif
48 
49 int main(int, char**) {
50     test ( "ABCDE", 5 );
51     test ( "a", 1 );
52     test ( "", 0 );
53 
54     test ( L"ABCDE", 5 );
55     test ( L"a", 1 );
56     test ( L"", 0 );
57 
58 #if TEST_STD_VER >= 11
59     test ( u"ABCDE", 5 );
60     test ( u"a", 1 );
61     test ( u"", 0 );
62 
63     test ( U"ABCDE", 5 );
64     test ( U"a", 1 );
65     test ( U"", 0 );
66 #endif
67 
68 #if TEST_STD_VER > 11
69     {
70     static_assert ( test_ce ( 5, 0 ) == 5, "" );
71     static_assert ( test_ce ( 5, 1 ) == 4, "" );
72     static_assert ( test_ce ( 5, 5 ) == 0, "" );
73     static_assert ( test_ce ( 9, 3 ) == 6, "" );
74     }
75 #endif
76 
77   return 0;
78 }
79