/src/skia/third_party/externals/icu/source/common/unicode/stringpiece.h
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1 | | // © 2016 and later: Unicode, Inc. and others. |
2 | | // License & terms of use: http://www.unicode.org/copyright.html |
3 | | // Copyright (C) 2009-2013, International Business Machines |
4 | | // Corporation and others. All Rights Reserved. |
5 | | // |
6 | | // Copyright 2001 and onwards Google Inc. |
7 | | // Author: Sanjay Ghemawat |
8 | | |
9 | | // This code is a contribution of Google code, and the style used here is |
10 | | // a compromise between the original Google code and the ICU coding guidelines. |
11 | | // For example, data types are ICU-ified (size_t,int->int32_t), |
12 | | // and API comments doxygen-ified, but function names and behavior are |
13 | | // as in the original, if possible. |
14 | | // Assertion-style error handling, not available in ICU, was changed to |
15 | | // parameter "pinning" similar to UnicodeString. |
16 | | // |
17 | | // In addition, this is only a partial port of the original Google code, |
18 | | // limited to what was needed so far. The (nearly) complete original code |
19 | | // is in the ICU svn repository at icuhtml/trunk/design/strings/contrib |
20 | | // (see ICU ticket 6765, r25517). |
21 | | |
22 | | #ifndef __STRINGPIECE_H__ |
23 | | #define __STRINGPIECE_H__ |
24 | | |
25 | | /** |
26 | | * \file |
27 | | * \brief C++ API: StringPiece: Read-only byte string wrapper class. |
28 | | */ |
29 | | |
30 | | #include "unicode/utypes.h" |
31 | | |
32 | | #if U_SHOW_CPLUSPLUS_API |
33 | | |
34 | | #include <cstddef> |
35 | | #include <type_traits> |
36 | | |
37 | | #include "unicode/uobject.h" |
38 | | #include "unicode/std_string.h" |
39 | | |
40 | | // Arghh! I wish C++ literals were "string". |
41 | | |
42 | | U_NAMESPACE_BEGIN |
43 | | |
44 | | /** |
45 | | * A string-like object that points to a sized piece of memory. |
46 | | * |
47 | | * We provide non-explicit singleton constructors so users can pass |
48 | | * in a "const char*" or a "string" wherever a "StringPiece" is |
49 | | * expected. |
50 | | * |
51 | | * Functions or methods may use StringPiece parameters to accept either a |
52 | | * "const char*" or a "string" value that will be implicitly converted to a |
53 | | * StringPiece. |
54 | | * |
55 | | * Systematic usage of StringPiece is encouraged as it will reduce unnecessary |
56 | | * conversions from "const char*" to "string" and back again. |
57 | | * |
58 | | * @stable ICU 4.2 |
59 | | */ |
60 | | class U_COMMON_API StringPiece : public UMemory { |
61 | | private: |
62 | | const char* ptr_; |
63 | | int32_t length_; |
64 | | |
65 | | public: |
66 | | /** |
67 | | * Default constructor, creates an empty StringPiece. |
68 | | * @stable ICU 4.2 |
69 | | */ |
70 | | StringPiece() : ptr_(nullptr), length_(0) { } |
71 | | |
72 | | /** |
73 | | * Constructs from a NUL-terminated const char * pointer. |
74 | | * @param str a NUL-terminated const char * pointer |
75 | | * @stable ICU 4.2 |
76 | | */ |
77 | | StringPiece(const char* str); |
78 | | #if defined(__cpp_char8_t) || defined(U_IN_DOXYGEN) |
79 | | /** |
80 | | * Constructs from a NUL-terminated const char8_t * pointer. |
81 | | * @param str a NUL-terminated const char8_t * pointer |
82 | | * @stable ICU 67 |
83 | | */ |
84 | | StringPiece(const char8_t* str) : StringPiece(reinterpret_cast<const char*>(str)) {} |
85 | | #endif |
86 | | /** |
87 | | * Constructs an empty StringPiece. |
88 | | * Needed for type disambiguation from multiple other overloads. |
89 | | * @param p nullptr |
90 | | * @stable ICU 67 |
91 | | */ |
92 | 0 | StringPiece(std::nullptr_t p) : ptr_(p), length_(0) {} |
93 | | |
94 | | /** |
95 | | * Constructs from a std::string. |
96 | | * @stable ICU 4.2 |
97 | | */ |
98 | | StringPiece(const std::string& str) |
99 | 0 | : ptr_(str.data()), length_(static_cast<int32_t>(str.size())) { } |
100 | | #if defined(__cpp_lib_char8_t) || defined(U_IN_DOXYGEN) |
101 | | /** |
102 | | * Constructs from a std::u8string. |
103 | | * @stable ICU 67 |
104 | | */ |
105 | | StringPiece(const std::u8string& str) |
106 | | : ptr_(reinterpret_cast<const char*>(str.data())), |
107 | | length_(static_cast<int32_t>(str.size())) { } |
108 | | #endif |
109 | | |
110 | | /** |
111 | | * Constructs from some other implementation of a string piece class, from any |
112 | | * C++ record type that has these two methods: |
113 | | * |
114 | | * \code{.cpp} |
115 | | * |
116 | | * struct OtherStringPieceClass { |
117 | | * const char* data(); // or const char8_t* |
118 | | * size_t size(); |
119 | | * }; |
120 | | * |
121 | | * \endcode |
122 | | * |
123 | | * The other string piece class will typically be std::string_view from C++17 |
124 | | * or absl::string_view from Abseil. |
125 | | * |
126 | | * Starting with C++20, data() may also return a const char8_t* pointer, |
127 | | * as from std::u8string_view. |
128 | | * |
129 | | * @param str the other string piece |
130 | | * @stable ICU 65 |
131 | | */ |
132 | | template <typename T, |
133 | | typename = typename std::enable_if< |
134 | | (std::is_same<decltype(T().data()), const char*>::value |
135 | | #if defined(__cpp_char8_t) |
136 | | || std::is_same<decltype(T().data()), const char8_t*>::value |
137 | | #endif |
138 | | ) && |
139 | | std::is_same<decltype(T().size()), size_t>::value>::type> |
140 | | StringPiece(T str) |
141 | | : ptr_(reinterpret_cast<const char*>(str.data())), |
142 | | length_(static_cast<int32_t>(str.size())) {} |
143 | | |
144 | | /** |
145 | | * Constructs from a const char * pointer and a specified length. |
146 | | * @param offset a const char * pointer (need not be terminated) |
147 | | * @param len the length of the string; must be non-negative |
148 | | * @stable ICU 4.2 |
149 | | */ |
150 | | StringPiece(const char* offset, int32_t len) : ptr_(offset), length_(len) { } |
151 | | #if defined(__cpp_char8_t) || defined(U_IN_DOXYGEN) |
152 | | /** |
153 | | * Constructs from a const char8_t * pointer and a specified length. |
154 | | * @param str a const char8_t * pointer (need not be terminated) |
155 | | * @param len the length of the string; must be non-negative |
156 | | * @stable ICU 67 |
157 | | */ |
158 | | StringPiece(const char8_t* str, int32_t len) : |
159 | | StringPiece(reinterpret_cast<const char*>(str), len) {} |
160 | | #endif |
161 | | |
162 | | /** |
163 | | * Substring of another StringPiece. |
164 | | * @param x the other StringPiece |
165 | | * @param pos start position in x; must be non-negative and <= x.length(). |
166 | | * @stable ICU 4.2 |
167 | | */ |
168 | | StringPiece(const StringPiece& x, int32_t pos); |
169 | | /** |
170 | | * Substring of another StringPiece. |
171 | | * @param x the other StringPiece |
172 | | * @param pos start position in x; must be non-negative and <= x.length(). |
173 | | * @param len length of the substring; |
174 | | * must be non-negative and will be pinned to at most x.length() - pos. |
175 | | * @stable ICU 4.2 |
176 | | */ |
177 | | StringPiece(const StringPiece& x, int32_t pos, int32_t len); |
178 | | |
179 | | /** |
180 | | * Returns the string pointer. May be nullptr if it is empty. |
181 | | * |
182 | | * data() may return a pointer to a buffer with embedded NULs, and the |
183 | | * returned buffer may or may not be null terminated. Therefore it is |
184 | | * typically a mistake to pass data() to a routine that expects a NUL |
185 | | * terminated string. |
186 | | * @return the string pointer |
187 | | * @stable ICU 4.2 |
188 | | */ |
189 | 451k | const char* data() const { return ptr_; } |
190 | | /** |
191 | | * Returns the string length. Same as length(). |
192 | | * @return the string length |
193 | | * @stable ICU 4.2 |
194 | | */ |
195 | 0 | int32_t size() const { return length_; } |
196 | | /** |
197 | | * Returns the string length. Same as size(). |
198 | | * @return the string length |
199 | | * @stable ICU 4.2 |
200 | | */ |
201 | 451k | int32_t length() const { return length_; } |
202 | | /** |
203 | | * Returns whether the string is empty. |
204 | | * @return true if the string is empty |
205 | | * @stable ICU 4.2 |
206 | | */ |
207 | 0 | UBool empty() const { return length_ == 0; } |
208 | | |
209 | | /** |
210 | | * Sets to an empty string. |
211 | | * @stable ICU 4.2 |
212 | | */ |
213 | 0 | void clear() { ptr_ = nullptr; length_ = 0; } |
214 | | |
215 | | /** |
216 | | * Reset the stringpiece to refer to new data. |
217 | | * @param xdata pointer the new string data. Need not be nul terminated. |
218 | | * @param len the length of the new data |
219 | | * @stable ICU 4.8 |
220 | | */ |
221 | 0 | void set(const char* xdata, int32_t len) { ptr_ = xdata; length_ = len; } |
222 | | |
223 | | /** |
224 | | * Reset the stringpiece to refer to new data. |
225 | | * @param str a pointer to a NUL-terminated string. |
226 | | * @stable ICU 4.8 |
227 | | */ |
228 | | void set(const char* str); |
229 | | |
230 | | #if defined(__cpp_char8_t) || defined(U_IN_DOXYGEN) |
231 | | /** |
232 | | * Resets the stringpiece to refer to new data. |
233 | | * @param xdata pointer the new string data. Need not be NUL-terminated. |
234 | | * @param len the length of the new data |
235 | | * @stable ICU 67 |
236 | | */ |
237 | | inline void set(const char8_t* xdata, int32_t len) { |
238 | | set(reinterpret_cast<const char*>(xdata), len); |
239 | | } |
240 | | |
241 | | /** |
242 | | * Resets the stringpiece to refer to new data. |
243 | | * @param str a pointer to a NUL-terminated string. |
244 | | * @stable ICU 67 |
245 | | */ |
246 | | inline void set(const char8_t* str) { |
247 | | set(reinterpret_cast<const char*>(str)); |
248 | | } |
249 | | #endif |
250 | | |
251 | | /** |
252 | | * Removes the first n string units. |
253 | | * @param n prefix length, must be non-negative and <=length() |
254 | | * @stable ICU 4.2 |
255 | | */ |
256 | 0 | void remove_prefix(int32_t n) { |
257 | 0 | if (n >= 0) { |
258 | 0 | if (n > length_) { |
259 | 0 | n = length_; |
260 | 0 | } |
261 | 0 | ptr_ += n; |
262 | 0 | length_ -= n; |
263 | 0 | } |
264 | 0 | } |
265 | | |
266 | | /** |
267 | | * Removes the last n string units. |
268 | | * @param n suffix length, must be non-negative and <=length() |
269 | | * @stable ICU 4.2 |
270 | | */ |
271 | 0 | void remove_suffix(int32_t n) { |
272 | 0 | if (n >= 0) { |
273 | 0 | if (n <= length_) { |
274 | 0 | length_ -= n; |
275 | 0 | } else { |
276 | 0 | length_ = 0; |
277 | 0 | } |
278 | 0 | } |
279 | 0 | } |
280 | | |
281 | | /** |
282 | | * Searches the StringPiece for the given search string (needle); |
283 | | * @param needle The string for which to search. |
284 | | * @param offset Where to start searching within this string (haystack). |
285 | | * @return The offset of needle in haystack, or -1 if not found. |
286 | | * @stable ICU 67 |
287 | | */ |
288 | | int32_t find(StringPiece needle, int32_t offset); |
289 | | |
290 | | /** |
291 | | * Compares this StringPiece with the other StringPiece, with semantics |
292 | | * similar to std::string::compare(). |
293 | | * @param other The string to compare to. |
294 | | * @return below zero if this < other; above zero if this > other; 0 if this == other. |
295 | | * @stable ICU 67 |
296 | | */ |
297 | | int32_t compare(StringPiece other); |
298 | | |
299 | | /** |
300 | | * Maximum integer, used as a default value for substring methods. |
301 | | * @stable ICU 4.2 |
302 | | */ |
303 | | static const int32_t npos; // = 0x7fffffff; |
304 | | |
305 | | /** |
306 | | * Returns a substring of this StringPiece. |
307 | | * @param pos start position; must be non-negative and <= length(). |
308 | | * @param len length of the substring; |
309 | | * must be non-negative and will be pinned to at most length() - pos. |
310 | | * @return the substring StringPiece |
311 | | * @stable ICU 4.2 |
312 | | */ |
313 | 0 | StringPiece substr(int32_t pos, int32_t len = npos) const { |
314 | 0 | return StringPiece(*this, pos, len); |
315 | 0 | } |
316 | | }; |
317 | | |
318 | | /** |
319 | | * Global operator == for StringPiece |
320 | | * @param x The first StringPiece to compare. |
321 | | * @param y The second StringPiece to compare. |
322 | | * @return true if the string data is equal |
323 | | * @stable ICU 4.8 |
324 | | */ |
325 | | U_EXPORT UBool U_EXPORT2 |
326 | | operator==(const StringPiece& x, const StringPiece& y); |
327 | | |
328 | | /** |
329 | | * Global operator != for StringPiece |
330 | | * @param x The first StringPiece to compare. |
331 | | * @param y The second StringPiece to compare. |
332 | | * @return true if the string data is not equal |
333 | | * @stable ICU 4.8 |
334 | | */ |
335 | 0 | inline UBool operator!=(const StringPiece& x, const StringPiece& y) { |
336 | 0 | return !(x == y); |
337 | 0 | } |
338 | | |
339 | | U_NAMESPACE_END |
340 | | |
341 | | #endif /* U_SHOW_CPLUSPLUS_API */ |
342 | | |
343 | | #endif // __STRINGPIECE_H__ |