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