1// SPDX-License-Identifier: GPL-3.0-or-later
2
3#pragma once
4
5#include <algorithm>
6#include <cstddef>
7#include <mos/cpp_support.hpp>
8
9namespace mos
10{
11 template<typename CharT>
12 constexpr auto generic_strlen(const CharT *c)
13 {
14 if (!c)
15 return size_t(0);
16 size_t len = 0;
17 while (*(c++))
18 {
19 len++;
20 }
21 return len;
22 }
23
24 template<typename CharT>
25 constexpr auto generic_strnlen(const CharT *c, size_t max)
26 {
27 size_t len = 0;
28 while (len < max && *(c++))
29 {
30 len++;
31 }
32 return len;
33 }
34
35 template<typename CharT>
36 constexpr auto generic_strncmp(const CharT *a, const CharT *b, size_t n)
37 {
38 for (size_t i = 0; i < n; i++)
39 {
40 if (a[i] != b[i])
41 return a[i] - b[i];
42 }
43 return 0;
44 }
45
46 template<typename CharT>
47 class basic_string_view
48 {
49 public:
50 static constexpr auto npos = size_t(-1);
51 basic_string_view(std::nullptr_t) = delete;
52 constexpr basic_string_view() : _pointer(nullptr), _length(0) {};
53 constexpr basic_string_view(const CharT *cs) : _pointer(cs), _length(generic_strlen(cs))
54 {
55 if (_pointer == nullptr)
56 mos::__raise_null_pointer_exception();
57 }
58
59 constexpr basic_string_view(const CharT *s, size_t length) : _pointer(s), _length(length)
60 {
61 if (_pointer == nullptr)
62 mos::__raise_null_pointer_exception();
63 }
64
65 constexpr basic_string_view(const CharT *begin, const CharT *end) : _pointer(begin), _length(end - begin)
66 {
67 if (_pointer == nullptr)
68 mos::__raise_null_pointer_exception();
69 }
70
71 const CharT *data() const
72 {
73 return _pointer;
74 }
75
76 const CharT &operator[](size_t index) const
77 {
78 return _pointer[index];
79 }
80
81 size_t size() const
82 {
83 return _length;
84 }
85
86 bool begins_with(CharT c) const
87 {
88 return _length > 0 && _pointer[0] == c;
89 }
90
91 bool begins_with(basic_string_view str) const
92 {
93 if (_length < str._length)
94 return false;
95
96 return generic_strncmp(_pointer, str._pointer, str._length) == 0;
97 }
98
99 bool ends_with(CharT c) const
100 {
101 return _length > 0 && _pointer[_length - 1] == c;
102 }
103
104 bool ends_with(basic_string_view str) const
105 {
106 if (_length < str._length)
107 return false;
108
109 return generic_strncmp(_pointer + _length - str._length, str._pointer, str._length) == 0;
110 }
111
112 constexpr bool empty() const
113 {
114 return _length == 0;
115 }
116
117 bool operator==(basic_string_view other) const
118 {
119 if (_length != other._length)
120 return false;
121
122 return generic_strncmp(_pointer, other._pointer, _length) == 0;
123 }
124
125 constexpr basic_string_view substr(size_t start, size_t end = -1) const
126 {
127 const auto len = std::min<size_t>(a: end, b: _length - start);
128 return basic_string_view(_pointer + start, len);
129 }
130
131 constexpr size_t find(CharT c, size_t start = 0) const
132 {
133 if (start >= _length)
134 return npos;
135
136 for (size_t i = start; i < _length; i++)
137 {
138 if (_pointer[i] == c)
139 return i;
140 }
141 return npos;
142 }
143
144 constexpr size_t find(basic_string_view str) const
145 {
146 for (size_t i = 0; i < _length; i++)
147 {
148 if (generic_strncmp(_pointer + i, str._pointer, str._length) == 0)
149 return i;
150 }
151 return npos;
152 }
153
154 constexpr bool starts_with(basic_string_view str) const
155 {
156 return generic_strncmp(_pointer, str._pointer, str._length) == 0;
157 }
158
159 private:
160 const CharT *_pointer;
161 size_t _length;
162 };
163
164 typedef basic_string_view<char> string_view;
165
166 namespace string_literals
167 {
168 constexpr string_view operator"" _sv(const char *str, size_t len)
169 {
170 return string_view(str, len);
171 }
172 } // namespace string_literals
173} // namespace mos
174