1 // -*- C++ -*-
2 //===----------------------------------------------------------------------===//
3 //
4 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5 // See https://llvm.org/LICENSE.txt for license information.
6 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7 //
8 //===----------------------------------------------------------------------===//
9
10 #ifndef _CONSTEXPR_CHAR_TRAITS
11 #define _CONSTEXPR_CHAR_TRAITS
12
13 #include <string>
14 #include <cassert>
15 #include <cstddef>
16
17 #include "test_macros.h"
18
19 template <class CharT>
20 struct constexpr_char_traits
21 {
22 typedef CharT char_type;
23 typedef int int_type;
24 typedef std::streamoff off_type;
25 typedef std::streampos pos_type;
26 typedef std::mbstate_t state_type;
27 // The comparison_category is omitted so the class will have weak_ordering
28 // in C++20. This is intentional.
29
assignconstexpr_char_traits30 static TEST_CONSTEXPR_CXX14 void assign(char_type& c1, const char_type& c2) TEST_NOEXCEPT
31 {c1 = c2;}
32
eqconstexpr_char_traits33 static TEST_CONSTEXPR bool eq(char_type c1, char_type c2) TEST_NOEXCEPT
34 {return c1 == c2;}
35
ltconstexpr_char_traits36 static TEST_CONSTEXPR bool lt(char_type c1, char_type c2) TEST_NOEXCEPT
37 {return c1 < c2;}
38
39 static TEST_CONSTEXPR_CXX14 int compare(const char_type* s1, const char_type* s2, std::size_t n);
40 static TEST_CONSTEXPR_CXX14 std::size_t length(const char_type* s);
41 static TEST_CONSTEXPR_CXX14 const char_type* find(const char_type* s, std::size_t n, const char_type& a);
42 static TEST_CONSTEXPR_CXX14 char_type* move(char_type* s1, const char_type* s2, std::size_t n);
43 static TEST_CONSTEXPR_CXX14 char_type* copy(char_type* s1, const char_type* s2, std::size_t n);
44 static TEST_CONSTEXPR_CXX14 char_type* assign(char_type* s, std::size_t n, char_type a);
45
not_eofconstexpr_char_traits46 static TEST_CONSTEXPR int_type not_eof(int_type c) TEST_NOEXCEPT
47 {return eq_int_type(c, eof()) ? ~eof() : c;}
48
to_char_typeconstexpr_char_traits49 static TEST_CONSTEXPR char_type to_char_type(int_type c) TEST_NOEXCEPT
50 {return char_type(c);}
51
to_int_typeconstexpr_char_traits52 static TEST_CONSTEXPR int_type to_int_type(char_type c) TEST_NOEXCEPT
53 {return int_type(c);}
54
eq_int_typeconstexpr_char_traits55 static TEST_CONSTEXPR bool eq_int_type(int_type c1, int_type c2) TEST_NOEXCEPT
56 {return c1 == c2;}
57
eofconstexpr_char_traits58 static TEST_CONSTEXPR int_type eof() TEST_NOEXCEPT
59 {return int_type(EOF);}
60 };
61
62
63 template <class CharT>
64 TEST_CONSTEXPR_CXX14 int
compare(const char_type * s1,const char_type * s2,std::size_t n)65 constexpr_char_traits<CharT>::compare(const char_type* s1, const char_type* s2, std::size_t n)
66 {
67 for (; n; --n, ++s1, ++s2)
68 {
69 if (lt(*s1, *s2))
70 return -1;
71 if (lt(*s2, *s1))
72 return 1;
73 }
74 return 0;
75 }
76
77 template <class CharT>
78 TEST_CONSTEXPR_CXX14 std::size_t
length(const char_type * s)79 constexpr_char_traits<CharT>::length(const char_type* s)
80 {
81 std::size_t len = 0;
82 for (; !eq(*s, char_type(0)); ++s)
83 ++len;
84 return len;
85 }
86
87 template <class CharT>
88 TEST_CONSTEXPR_CXX14 const CharT*
find(const char_type * s,std::size_t n,const char_type & a)89 constexpr_char_traits<CharT>::find(const char_type* s, std::size_t n, const char_type& a)
90 {
91 for (; n; --n)
92 {
93 if (eq(*s, a))
94 return s;
95 ++s;
96 }
97 return 0;
98 }
99
100 template <class CharT>
101 TEST_CONSTEXPR_CXX14 CharT*
move(char_type * s1,const char_type * s2,std::size_t n)102 constexpr_char_traits<CharT>::move(char_type* s1, const char_type* s2, std::size_t n)
103 {
104 char_type* r = s1;
105 if (s1 < s2)
106 {
107 for (; n; --n, ++s1, ++s2)
108 assign(*s1, *s2);
109 }
110 else if (s2 < s1)
111 {
112 s1 += n;
113 s2 += n;
114 for (; n; --n)
115 assign(*--s1, *--s2);
116 }
117 return r;
118 }
119
120 template <class CharT>
121 TEST_CONSTEXPR_CXX14 CharT*
copy(char_type * s1,const char_type * s2,std::size_t n)122 constexpr_char_traits<CharT>::copy(char_type* s1, const char_type* s2, std::size_t n)
123 {
124 if (!TEST_IS_CONSTANT_EVALUATED) // fails in constexpr because we might be comparing unrelated pointers
125 assert(s2 < s1 || s2 >= s1+n);
126 char_type* r = s1;
127 for (; n; --n, ++s1, ++s2)
128 assign(*s1, *s2);
129 return r;
130 }
131
132 template <class CharT>
133 TEST_CONSTEXPR_CXX14 CharT*
assign(char_type * s,std::size_t n,char_type a)134 constexpr_char_traits<CharT>::assign(char_type* s, std::size_t n, char_type a)
135 {
136 char_type* r = s;
137 for (; n; --n, ++s)
138 assign(*s, a);
139 return r;
140 }
141
142 #endif // _CONSTEXPR_CHAR_TRAITS
143