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339e8bc4 PP |
1 | /* |
2 | * Copyright (c) 2023 Philippe Proulx <pproulx@efficios.com> | |
3 | * | |
4 | * SPDX-License-Identifier: MIT | |
5 | */ | |
6 | ||
7 | #ifndef BABELTRACE_CPP_COMMON_BT2C_C_STRING_VIEW_HPP | |
8 | #define BABELTRACE_CPP_COMMON_BT2C_C_STRING_VIEW_HPP | |
9 | ||
10 | #include <cstddef> | |
11 | #include <cstring> | |
12 | #include <string> | |
13 | ||
14 | #include "common/assert.h" | |
15 | #include "cpp-common/bt2s/string-view.hpp" | |
7c9d996f | 16 | #include "cpp-common/vendor/fmt/format.h" /* IWYU pragma: keep */ |
339e8bc4 | 17 | |
821af099 SM |
18 | #include "type-traits.hpp" |
19 | ||
339e8bc4 PP |
20 | namespace bt2c { |
21 | ||
22 | /* | |
23 | * A view on a constant null-terminated C string. | |
24 | * | |
25 | * Similar to `bt2s::string_view`, but len() and end() compute the | |
26 | * length on demand. | |
27 | */ | |
28 | class CStringView final | |
29 | { | |
30 | public: | |
31 | /* | |
32 | * Builds an empty view (data() returns `nullptr`). | |
33 | * | |
34 | * Intentionally not explicit. | |
35 | */ | |
26d1608e | 36 | constexpr CStringView() noexcept = default; |
339e8bc4 PP |
37 | |
38 | /* | |
39 | * Builds a view of the C string `str` (may be `nullptr`). | |
40 | * | |
41 | * Intentionally not explicit. | |
42 | */ | |
26d1608e | 43 | constexpr CStringView(const char * const str) noexcept : _mStr {str} |
339e8bc4 PP |
44 | { |
45 | } | |
46 | ||
a0ae532f SM |
47 | /* |
48 | * Builds a view of the string `str`. | |
49 | * | |
50 | * Intentionally not explicit. | |
51 | */ | |
52 | CStringView(const std::string& str) noexcept : _mStr {str.c_str()} | |
53 | { | |
54 | } | |
55 | ||
339e8bc4 PP |
56 | /* |
57 | * Makes this view view the C string `str` (may be `nullptr`). | |
58 | * | |
59 | * Intentionally not explicit. | |
60 | */ | |
61 | CStringView& operator=(const char * const str) noexcept | |
62 | { | |
63 | _mStr = str; | |
64 | return *this; | |
65 | } | |
66 | ||
67 | /* | |
68 | * Viewed null-terminated C string (may be `nullptr`). | |
69 | */ | |
70 | const char *data() const noexcept | |
71 | { | |
72 | return _mStr; | |
73 | } | |
74 | ||
75 | /* | |
76 | * Alias of data(). | |
77 | */ | |
78 | operator const char *() const noexcept | |
79 | { | |
80 | return this->data(); | |
81 | } | |
82 | ||
83 | /* | |
84 | * Alias of data(). | |
85 | */ | |
86 | const char *operator*() const noexcept | |
87 | { | |
88 | return this->data(); | |
89 | } | |
90 | ||
91 | /* | |
92 | * Alias of data(). | |
93 | * | |
94 | * data() must not return `nullptr`. | |
95 | */ | |
96 | const char *begin() const noexcept | |
97 | { | |
98 | BT_ASSERT_DBG(_mStr); | |
99 | return this->data(); | |
100 | } | |
101 | ||
102 | /* | |
103 | * Pointer to the null character of the viewed C string. | |
104 | * | |
105 | * data() must not return `nullptr`. | |
106 | */ | |
107 | const char *end() const noexcept | |
108 | { | |
109 | BT_ASSERT_DBG(_mStr); | |
110 | return _mStr + this->len(); | |
111 | } | |
112 | ||
113 | /* | |
114 | * Length of the viewed C string, excluding the null character. | |
115 | * | |
116 | * data() must not return `nullptr`. | |
117 | */ | |
118 | std::size_t len() const noexcept | |
119 | { | |
120 | BT_ASSERT_DBG(_mStr); | |
121 | return std::strlen(_mStr); | |
122 | } | |
123 | ||
124 | /* | |
125 | * Returns an `std::string` instance containing a copy of the viewed | |
126 | * C string. | |
127 | * | |
128 | * data() must not return `nullptr`. | |
129 | */ | |
130 | std::string str() const | |
131 | { | |
132 | BT_ASSERT_DBG(_mStr); | |
133 | return std::string {_mStr}; | |
134 | } | |
135 | ||
136 | /* | |
137 | * Alias of str(). | |
138 | */ | |
139 | operator std::string() const | |
140 | { | |
141 | return this->str(); | |
142 | } | |
143 | ||
144 | /* | |
145 | * Returns a `bt2s::string_view` instance to view the contents, | |
146 | * excluding the null character, of the viewed C string. | |
147 | */ | |
148 | bt2s::string_view strView() const noexcept | |
149 | { | |
150 | if (_mStr) { | |
151 | return bt2s::string_view {this->begin(), this->len()}; | |
152 | } else { | |
153 | return {}; | |
154 | } | |
155 | } | |
156 | ||
157 | /* | |
158 | * Alias of strView(). | |
159 | */ | |
160 | operator bt2s::string_view() const noexcept | |
161 | { | |
162 | return this->strView(); | |
163 | } | |
164 | ||
165 | /* | |
166 | * Returns the character at index `i`. | |
167 | * | |
168 | * `i` must be less than what len() returns. | |
169 | * | |
170 | * data() must not return `nullptr`. | |
171 | */ | |
172 | char operator[](const std::size_t i) const noexcept | |
173 | { | |
174 | BT_ASSERT_DBG(_mStr); | |
175 | BT_ASSERT_DBG(i < this->len()); | |
176 | return _mStr[i]; | |
177 | } | |
178 | ||
dc0f6dd1 SM |
179 | bool startsWith(const bt2c::CStringView prefix) const noexcept |
180 | { | |
181 | BT_ASSERT_DBG(_mStr); | |
182 | BT_ASSERT_DBG(prefix); | |
183 | return std::strncmp(_mStr, prefix, prefix.len()) == 0; | |
184 | } | |
185 | ||
339e8bc4 PP |
186 | private: |
187 | const char *_mStr = nullptr; | |
188 | }; | |
189 | ||
485083ae | 190 | inline const char *format_as(const CStringView& str) |
339e8bc4 | 191 | { |
e64addc7 SM |
192 | return str ? *str : "(null)"; |
193 | } | |
339e8bc4 | 194 | |
821af099 SM |
195 | namespace internal { |
196 | ||
197 | template <typename StrT> | |
198 | const char *asConstCharPtr(StrT&& val) noexcept | |
199 | { | |
200 | return val.data(); | |
201 | } | |
202 | ||
203 | inline const char *asConstCharPtr(const char * const val) noexcept | |
204 | { | |
205 | return val; | |
206 | } | |
207 | ||
208 | template <typename StrT> | |
209 | using ComparableWithCStringView = | |
210 | IsOneOf<typename std::decay<StrT>::type, CStringView, std::string, const char *>; | |
211 | ||
212 | } /* namespace internal */ | |
213 | ||
214 | /* | |
215 | * Returns true if `lhs` is equal to `rhs`. | |
216 | * | |
217 | * `LhsT` and `RhsT` may be any of: | |
218 | * | |
219 | * • `const char *` | |
220 | * • `std::string` | |
221 | * • `CStringView` | |
222 | * | |
223 | * Both `lhs` and `rhs` must not have an underlying `nullptr` raw data. | |
224 | */ | |
225 | template < | |
226 | typename LhsT, typename RhsT, | |
227 | typename = typename std::enable_if<internal::ComparableWithCStringView<LhsT>::value>::type, | |
228 | typename = typename std::enable_if<internal::ComparableWithCStringView<RhsT>::value>::type> | |
229 | bool operator==(LhsT&& lhs, RhsT&& rhs) noexcept | |
230 | { | |
231 | const auto rawLhs = internal::asConstCharPtr(lhs); | |
232 | const auto rawRhs = internal::asConstCharPtr(rhs); | |
233 | ||
234 | BT_ASSERT_DBG(rawLhs); | |
235 | BT_ASSERT_DBG(rawRhs); | |
236 | return std::strcmp(rawLhs, rawRhs) == 0; | |
237 | } | |
238 | ||
239 | /* | |
240 | * Returns true if `lhs` is not equal to `rhs`. | |
241 | * | |
242 | * `LhsT` and `RhsT` may be any of: | |
243 | * | |
244 | * • `const char *` | |
245 | * • `std::string` | |
246 | * • `CStringView` | |
247 | * | |
248 | * Both `lhs` and `rhs` must not have an underlying `nullptr` raw data. | |
249 | */ | |
ab3bed93 SM |
250 | template < |
251 | typename LhsT, typename RhsT, | |
252 | typename = typename std::enable_if<internal::ComparableWithCStringView<LhsT>::value>::type, | |
253 | typename = typename std::enable_if<internal::ComparableWithCStringView<RhsT>::value>::type> | |
821af099 SM |
254 | bool operator!=(LhsT&& lhs, RhsT&& rhs) noexcept |
255 | { | |
256 | return !(std::forward<LhsT>(lhs) == std::forward<RhsT>(rhs)); | |
257 | } | |
258 | ||
e64addc7 | 259 | } /* namespace bt2c */ |
339e8bc4 PP |
260 | |
261 | #endif /* BABELTRACE_CPP_COMMON_BT2C_C_STRING_VIEW_HPP */ |