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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" | |
e64addc7 | 16 | #include "cpp-common/vendor/fmt/format.h" |
339e8bc4 PP |
17 | |
18 | namespace bt2c { | |
19 | ||
20 | /* | |
21 | * A view on a constant null-terminated C string. | |
22 | * | |
23 | * Similar to `bt2s::string_view`, but len() and end() compute the | |
24 | * length on demand. | |
25 | */ | |
26 | class CStringView final | |
27 | { | |
28 | public: | |
29 | /* | |
30 | * Builds an empty view (data() returns `nullptr`). | |
31 | * | |
32 | * Intentionally not explicit. | |
33 | */ | |
34 | CStringView() noexcept = default; | |
35 | ||
36 | /* | |
37 | * Builds a view of the C string `str` (may be `nullptr`). | |
38 | * | |
39 | * Intentionally not explicit. | |
40 | */ | |
41 | CStringView(const char * const str) noexcept : _mStr {str} | |
42 | { | |
43 | } | |
44 | ||
45 | /* | |
46 | * Makes this view view the C string `str` (may be `nullptr`). | |
47 | * | |
48 | * Intentionally not explicit. | |
49 | */ | |
50 | CStringView& operator=(const char * const str) noexcept | |
51 | { | |
52 | _mStr = str; | |
53 | return *this; | |
54 | } | |
55 | ||
56 | /* | |
57 | * Viewed null-terminated C string (may be `nullptr`). | |
58 | */ | |
59 | const char *data() const noexcept | |
60 | { | |
61 | return _mStr; | |
62 | } | |
63 | ||
64 | /* | |
65 | * Alias of data(). | |
66 | */ | |
67 | operator const char *() const noexcept | |
68 | { | |
69 | return this->data(); | |
70 | } | |
71 | ||
72 | /* | |
73 | * Alias of data(). | |
74 | */ | |
75 | const char *operator*() const noexcept | |
76 | { | |
77 | return this->data(); | |
78 | } | |
79 | ||
80 | /* | |
81 | * Alias of data(). | |
82 | * | |
83 | * data() must not return `nullptr`. | |
84 | */ | |
85 | const char *begin() const noexcept | |
86 | { | |
87 | BT_ASSERT_DBG(_mStr); | |
88 | return this->data(); | |
89 | } | |
90 | ||
91 | /* | |
92 | * Pointer to the null character of the viewed C string. | |
93 | * | |
94 | * data() must not return `nullptr`. | |
95 | */ | |
96 | const char *end() const noexcept | |
97 | { | |
98 | BT_ASSERT_DBG(_mStr); | |
99 | return _mStr + this->len(); | |
100 | } | |
101 | ||
102 | /* | |
103 | * Length of the viewed C string, excluding the null character. | |
104 | * | |
105 | * data() must not return `nullptr`. | |
106 | */ | |
107 | std::size_t len() const noexcept | |
108 | { | |
109 | BT_ASSERT_DBG(_mStr); | |
110 | return std::strlen(_mStr); | |
111 | } | |
112 | ||
113 | /* | |
114 | * Returns an `std::string` instance containing a copy of the viewed | |
115 | * C string. | |
116 | * | |
117 | * data() must not return `nullptr`. | |
118 | */ | |
119 | std::string str() const | |
120 | { | |
121 | BT_ASSERT_DBG(_mStr); | |
122 | return std::string {_mStr}; | |
123 | } | |
124 | ||
125 | /* | |
126 | * Alias of str(). | |
127 | */ | |
128 | operator std::string() const | |
129 | { | |
130 | return this->str(); | |
131 | } | |
132 | ||
133 | /* | |
134 | * Returns a `bt2s::string_view` instance to view the contents, | |
135 | * excluding the null character, of the viewed C string. | |
136 | */ | |
137 | bt2s::string_view strView() const noexcept | |
138 | { | |
139 | if (_mStr) { | |
140 | return bt2s::string_view {this->begin(), this->len()}; | |
141 | } else { | |
142 | return {}; | |
143 | } | |
144 | } | |
145 | ||
146 | /* | |
147 | * Alias of strView(). | |
148 | */ | |
149 | operator bt2s::string_view() const noexcept | |
150 | { | |
151 | return this->strView(); | |
152 | } | |
153 | ||
154 | /* | |
155 | * Returns the character at index `i`. | |
156 | * | |
157 | * `i` must be less than what len() returns. | |
158 | * | |
159 | * data() must not return `nullptr`. | |
160 | */ | |
161 | char operator[](const std::size_t i) const noexcept | |
162 | { | |
163 | BT_ASSERT_DBG(_mStr); | |
164 | BT_ASSERT_DBG(i < this->len()); | |
165 | return _mStr[i]; | |
166 | } | |
167 | ||
168 | private: | |
169 | const char *_mStr = nullptr; | |
170 | }; | |
171 | ||
e64addc7 | 172 | static inline const char *format_as(const CStringView& str) |
339e8bc4 | 173 | { |
e64addc7 SM |
174 | return str ? *str : "(null)"; |
175 | } | |
339e8bc4 | 176 | |
e64addc7 | 177 | } /* namespace bt2c */ |
339e8bc4 PP |
178 | |
179 | #endif /* BABELTRACE_CPP_COMMON_BT2C_C_STRING_VIEW_HPP */ |