/src/LPM/external.protobuf/include/absl/strings/str_cat.h
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1 | | // |
2 | | // Copyright 2017 The Abseil Authors. |
3 | | // |
4 | | // Licensed under the Apache License, Version 2.0 (the "License"); |
5 | | // you may not use this file except in compliance with the License. |
6 | | // You may obtain a copy of the License at |
7 | | // |
8 | | // https://www.apache.org/licenses/LICENSE-2.0 |
9 | | // |
10 | | // Unless required by applicable law or agreed to in writing, software |
11 | | // distributed under the License is distributed on an "AS IS" BASIS, |
12 | | // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
13 | | // See the License for the specific language governing permissions and |
14 | | // limitations under the License. |
15 | | // |
16 | | // ----------------------------------------------------------------------------- |
17 | | // File: str_cat.h |
18 | | // ----------------------------------------------------------------------------- |
19 | | // |
20 | | // This package contains functions for efficiently concatenating and appending |
21 | | // strings: `StrCat()` and `StrAppend()`. Most of the work within these routines |
22 | | // is actually handled through use of a special AlphaNum type, which was |
23 | | // designed to be used as a parameter type that efficiently manages conversion |
24 | | // to strings and avoids copies in the above operations. |
25 | | // |
26 | | // Any routine accepting either a string or a number may accept `AlphaNum`. |
27 | | // The basic idea is that by accepting a `const AlphaNum &` as an argument |
28 | | // to your function, your callers will automagically convert bools, integers, |
29 | | // and floating point values to strings for you. |
30 | | // |
31 | | // NOTE: Use of `AlphaNum` outside of the //absl/strings package is unsupported |
32 | | // except for the specific case of function parameters of type `AlphaNum` or |
33 | | // `const AlphaNum &`. In particular, instantiating `AlphaNum` directly as a |
34 | | // stack variable is not supported. |
35 | | // |
36 | | // Conversion from 8-bit values is not accepted because, if it were, then an |
37 | | // attempt to pass ':' instead of ":" might result in a 58 ending up in your |
38 | | // result. |
39 | | // |
40 | | // Bools convert to "0" or "1". Pointers to types other than `char *` are not |
41 | | // valid inputs. No output is generated for null `char *` pointers. |
42 | | // |
43 | | // Floating point numbers are formatted with six-digit precision, which is |
44 | | // the default for "std::cout <<" or printf "%g" (the same as "%.6g"). |
45 | | // |
46 | | // You can convert to hexadecimal output rather than decimal output using the |
47 | | // `Hex` type contained here. To do so, pass `Hex(my_int)` as a parameter to |
48 | | // `StrCat()` or `StrAppend()`. You may specify a minimum hex field width using |
49 | | // a `PadSpec` enum. |
50 | | // |
51 | | // User-defined types can be formatted with the `AbslStringify()` customization |
52 | | // point. The API relies on detecting an overload in the user-defined type's |
53 | | // namespace of a free (non-member) `AbslStringify()` function as a definition |
54 | | // (typically declared as a friend and implemented in-line. |
55 | | // with the following signature: |
56 | | // |
57 | | // class MyClass { ... }; |
58 | | // |
59 | | // template <typename Sink> |
60 | | // void AbslStringify(Sink& sink, const MyClass& value); |
61 | | // |
62 | | // An `AbslStringify()` overload for a type should only be declared in the same |
63 | | // file and namespace as said type. |
64 | | // |
65 | | // Note that `AbslStringify()` also supports use with `absl::StrFormat()` and |
66 | | // `absl::Substitute()`. |
67 | | // |
68 | | // Example: |
69 | | // |
70 | | // struct Point { |
71 | | // // To add formatting support to `Point`, we simply need to add a free |
72 | | // // (non-member) function `AbslStringify()`. This method specifies how |
73 | | // // Point should be printed when absl::StrCat() is called on it. You can add |
74 | | // // such a free function using a friend declaration within the body of the |
75 | | // // class. The sink parameter is a templated type to avoid requiring |
76 | | // // dependencies. |
77 | | // template <typename Sink> friend void AbslStringify(Sink& |
78 | | // sink, const Point& p) { |
79 | | // absl::Format(&sink, "(%v, %v)", p.x, p.y); |
80 | | // } |
81 | | // |
82 | | // int x; |
83 | | // int y; |
84 | | // }; |
85 | | // ----------------------------------------------------------------------------- |
86 | | |
87 | | #ifndef ABSL_STRINGS_STR_CAT_H_ |
88 | | #define ABSL_STRINGS_STR_CAT_H_ |
89 | | |
90 | | #include <array> |
91 | | #include <cstdint> |
92 | | #include <string> |
93 | | #include <type_traits> |
94 | | #include <utility> |
95 | | #include <vector> |
96 | | |
97 | | #include "absl/base/port.h" |
98 | | #include "absl/strings/internal/has_absl_stringify.h" |
99 | | #include "absl/strings/internal/stringify_sink.h" |
100 | | #include "absl/strings/numbers.h" |
101 | | #include "absl/strings/string_view.h" |
102 | | |
103 | | namespace absl { |
104 | | ABSL_NAMESPACE_BEGIN |
105 | | |
106 | | namespace strings_internal { |
107 | | // AlphaNumBuffer allows a way to pass a string to StrCat without having to do |
108 | | // memory allocation. It is simply a pair of a fixed-size character array, and |
109 | | // a size. Please don't use outside of absl, yet. |
110 | | template <size_t max_size> |
111 | | struct AlphaNumBuffer { |
112 | | std::array<char, max_size> data; |
113 | | size_t size; |
114 | | }; |
115 | | |
116 | | } // namespace strings_internal |
117 | | |
118 | | // Enum that specifies the number of significant digits to return in a `Hex` or |
119 | | // `Dec` conversion and fill character to use. A `kZeroPad2` value, for example, |
120 | | // would produce hexadecimal strings such as "0a","0f" and a 'kSpacePad5' value |
121 | | // would produce hexadecimal strings such as " a"," f". |
122 | | enum PadSpec : uint8_t { |
123 | | kNoPad = 1, |
124 | | kZeroPad2, |
125 | | kZeroPad3, |
126 | | kZeroPad4, |
127 | | kZeroPad5, |
128 | | kZeroPad6, |
129 | | kZeroPad7, |
130 | | kZeroPad8, |
131 | | kZeroPad9, |
132 | | kZeroPad10, |
133 | | kZeroPad11, |
134 | | kZeroPad12, |
135 | | kZeroPad13, |
136 | | kZeroPad14, |
137 | | kZeroPad15, |
138 | | kZeroPad16, |
139 | | kZeroPad17, |
140 | | kZeroPad18, |
141 | | kZeroPad19, |
142 | | kZeroPad20, |
143 | | |
144 | | kSpacePad2 = kZeroPad2 + 64, |
145 | | kSpacePad3, |
146 | | kSpacePad4, |
147 | | kSpacePad5, |
148 | | kSpacePad6, |
149 | | kSpacePad7, |
150 | | kSpacePad8, |
151 | | kSpacePad9, |
152 | | kSpacePad10, |
153 | | kSpacePad11, |
154 | | kSpacePad12, |
155 | | kSpacePad13, |
156 | | kSpacePad14, |
157 | | kSpacePad15, |
158 | | kSpacePad16, |
159 | | kSpacePad17, |
160 | | kSpacePad18, |
161 | | kSpacePad19, |
162 | | kSpacePad20, |
163 | | }; |
164 | | |
165 | | // ----------------------------------------------------------------------------- |
166 | | // Hex |
167 | | // ----------------------------------------------------------------------------- |
168 | | // |
169 | | // `Hex` stores a set of hexadecimal string conversion parameters for use |
170 | | // within `AlphaNum` string conversions. |
171 | | struct Hex { |
172 | | uint64_t value; |
173 | | uint8_t width; |
174 | | char fill; |
175 | | |
176 | | template <typename Int> |
177 | | explicit Hex( |
178 | | Int v, PadSpec spec = absl::kNoPad, |
179 | | typename std::enable_if<sizeof(Int) == 1 && |
180 | | !std::is_pointer<Int>::value>::type* = nullptr) |
181 | | : Hex(spec, static_cast<uint8_t>(v)) {} |
182 | | template <typename Int> |
183 | | explicit Hex( |
184 | | Int v, PadSpec spec = absl::kNoPad, |
185 | | typename std::enable_if<sizeof(Int) == 2 && |
186 | | !std::is_pointer<Int>::value>::type* = nullptr) |
187 | | : Hex(spec, static_cast<uint16_t>(v)) {} |
188 | | template <typename Int> |
189 | | explicit Hex( |
190 | | Int v, PadSpec spec = absl::kNoPad, |
191 | | typename std::enable_if<sizeof(Int) == 4 && |
192 | | !std::is_pointer<Int>::value>::type* = nullptr) |
193 | | : Hex(spec, static_cast<uint32_t>(v)) {} |
194 | | template <typename Int> |
195 | | explicit Hex( |
196 | | Int v, PadSpec spec = absl::kNoPad, |
197 | | typename std::enable_if<sizeof(Int) == 8 && |
198 | | !std::is_pointer<Int>::value>::type* = nullptr) |
199 | | : Hex(spec, static_cast<uint64_t>(v)) {} |
200 | | template <typename Pointee> |
201 | | explicit Hex(Pointee* v, PadSpec spec = absl::kNoPad) |
202 | | : Hex(spec, reinterpret_cast<uintptr_t>(v)) {} |
203 | | |
204 | | private: |
205 | | Hex(PadSpec spec, uint64_t v) |
206 | | : value(v), |
207 | | width(spec == absl::kNoPad |
208 | | ? 1 |
209 | | : spec >= absl::kSpacePad2 ? spec - absl::kSpacePad2 + 2 |
210 | | : spec - absl::kZeroPad2 + 2), |
211 | 0 | fill(spec >= absl::kSpacePad2 ? ' ' : '0') {} |
212 | | }; |
213 | | |
214 | | // ----------------------------------------------------------------------------- |
215 | | // Dec |
216 | | // ----------------------------------------------------------------------------- |
217 | | // |
218 | | // `Dec` stores a set of decimal string conversion parameters for use |
219 | | // within `AlphaNum` string conversions. Dec is slower than the default |
220 | | // integer conversion, so use it only if you need padding. |
221 | | struct Dec { |
222 | | uint64_t value; |
223 | | uint8_t width; |
224 | | char fill; |
225 | | bool neg; |
226 | | |
227 | | template <typename Int> |
228 | | explicit Dec(Int v, PadSpec spec = absl::kNoPad, |
229 | | typename std::enable_if<(sizeof(Int) <= 8)>::type* = nullptr) |
230 | | : value(v >= 0 ? static_cast<uint64_t>(v) |
231 | | : uint64_t{0} - static_cast<uint64_t>(v)), |
232 | | width(spec == absl::kNoPad |
233 | | ? 1 |
234 | | : spec >= absl::kSpacePad2 ? spec - absl::kSpacePad2 + 2 |
235 | | : spec - absl::kZeroPad2 + 2), |
236 | | fill(spec >= absl::kSpacePad2 ? ' ' : '0'), |
237 | | neg(v < 0) {} |
238 | | }; |
239 | | |
240 | | // ----------------------------------------------------------------------------- |
241 | | // AlphaNum |
242 | | // ----------------------------------------------------------------------------- |
243 | | // |
244 | | // The `AlphaNum` class acts as the main parameter type for `StrCat()` and |
245 | | // `StrAppend()`, providing efficient conversion of numeric, boolean, decimal, |
246 | | // and hexadecimal values (through the `Dec` and `Hex` types) into strings. |
247 | | // `AlphaNum` should only be used as a function parameter. Do not instantiate |
248 | | // `AlphaNum` directly as a stack variable. |
249 | | |
250 | | class AlphaNum { |
251 | | public: |
252 | | // No bool ctor -- bools convert to an integral type. |
253 | | // A bool ctor would also convert incoming pointers (bletch). |
254 | | |
255 | | AlphaNum(int x) // NOLINT(runtime/explicit) |
256 | | : piece_(digits_, static_cast<size_t>( |
257 | | numbers_internal::FastIntToBuffer(x, digits_) - |
258 | 0 | &digits_[0])) {} |
259 | | AlphaNum(unsigned int x) // NOLINT(runtime/explicit) |
260 | | : piece_(digits_, static_cast<size_t>( |
261 | | numbers_internal::FastIntToBuffer(x, digits_) - |
262 | 0 | &digits_[0])) {} |
263 | | AlphaNum(long x) // NOLINT(*) |
264 | | : piece_(digits_, static_cast<size_t>( |
265 | | numbers_internal::FastIntToBuffer(x, digits_) - |
266 | 0 | &digits_[0])) {} |
267 | | AlphaNum(unsigned long x) // NOLINT(*) |
268 | | : piece_(digits_, static_cast<size_t>( |
269 | | numbers_internal::FastIntToBuffer(x, digits_) - |
270 | 0 | &digits_[0])) {} |
271 | | AlphaNum(long long x) // NOLINT(*) |
272 | | : piece_(digits_, static_cast<size_t>( |
273 | | numbers_internal::FastIntToBuffer(x, digits_) - |
274 | 0 | &digits_[0])) {} |
275 | | AlphaNum(unsigned long long x) // NOLINT(*) |
276 | | : piece_(digits_, static_cast<size_t>( |
277 | | numbers_internal::FastIntToBuffer(x, digits_) - |
278 | 0 | &digits_[0])) {} |
279 | | |
280 | | AlphaNum(float f) // NOLINT(runtime/explicit) |
281 | 0 | : piece_(digits_, numbers_internal::SixDigitsToBuffer(f, digits_)) {} |
282 | | AlphaNum(double f) // NOLINT(runtime/explicit) |
283 | 0 | : piece_(digits_, numbers_internal::SixDigitsToBuffer(f, digits_)) {} |
284 | | |
285 | | AlphaNum(Hex hex); // NOLINT(runtime/explicit) |
286 | | AlphaNum(Dec dec); // NOLINT(runtime/explicit) |
287 | | |
288 | | template <size_t size> |
289 | | AlphaNum( // NOLINT(runtime/explicit) |
290 | | const strings_internal::AlphaNumBuffer<size>& buf) |
291 | | : piece_(&buf.data[0], buf.size) {} |
292 | | |
293 | | AlphaNum(const char* c_str) // NOLINT(runtime/explicit) |
294 | 0 | : piece_(NullSafeStringView(c_str)) {} // NOLINT(runtime/explicit) |
295 | 0 | AlphaNum(absl::string_view pc) : piece_(pc) {} // NOLINT(runtime/explicit) |
296 | | |
297 | | template <typename T, typename = typename std::enable_if< |
298 | | strings_internal::HasAbslStringify<T>::value>::type> |
299 | | AlphaNum( // NOLINT(runtime/explicit) |
300 | | const T& v, // NOLINT(runtime/explicit) |
301 | | strings_internal::StringifySink&& sink = {}) // NOLINT(runtime/explicit) |
302 | | : piece_(strings_internal::ExtractStringification(sink, v)) {} |
303 | | |
304 | | template <typename Allocator> |
305 | | AlphaNum( // NOLINT(runtime/explicit) |
306 | | const std::basic_string<char, std::char_traits<char>, Allocator>& str) |
307 | | : piece_(str) {} |
308 | | |
309 | | // Use string literals ":" instead of character literals ':'. |
310 | | AlphaNum(char c) = delete; // NOLINT(runtime/explicit) |
311 | | |
312 | | AlphaNum(const AlphaNum&) = delete; |
313 | | AlphaNum& operator=(const AlphaNum&) = delete; |
314 | | |
315 | 0 | absl::string_view::size_type size() const { return piece_.size(); } |
316 | 0 | const char* data() const { return piece_.data(); } |
317 | 0 | absl::string_view Piece() const { return piece_; } |
318 | | |
319 | | // Normal enums are already handled by the integer formatters. |
320 | | // This overload matches only scoped enums. |
321 | | template <typename T, |
322 | | typename = typename std::enable_if< |
323 | | std::is_enum<T>{} && !std::is_convertible<T, int>{} && |
324 | | !strings_internal::HasAbslStringify<T>::value>::type> |
325 | | AlphaNum(T e) // NOLINT(runtime/explicit) |
326 | | : AlphaNum(static_cast<typename std::underlying_type<T>::type>(e)) {} |
327 | | |
328 | | // vector<bool>::reference and const_reference require special help to |
329 | | // convert to `AlphaNum` because it requires two user defined conversions. |
330 | | template < |
331 | | typename T, |
332 | | typename std::enable_if< |
333 | | std::is_class<T>::value && |
334 | | (std::is_same<T, std::vector<bool>::reference>::value || |
335 | | std::is_same<T, std::vector<bool>::const_reference>::value)>::type* = |
336 | | nullptr> |
337 | | AlphaNum(T e) : AlphaNum(static_cast<bool>(e)) {} // NOLINT(runtime/explicit) |
338 | | |
339 | | private: |
340 | | absl::string_view piece_; |
341 | | char digits_[numbers_internal::kFastToBufferSize]; |
342 | | }; |
343 | | |
344 | | // ----------------------------------------------------------------------------- |
345 | | // StrCat() |
346 | | // ----------------------------------------------------------------------------- |
347 | | // |
348 | | // Merges given strings or numbers, using no delimiter(s), returning the merged |
349 | | // result as a string. |
350 | | // |
351 | | // `StrCat()` is designed to be the fastest possible way to construct a string |
352 | | // out of a mix of raw C strings, string_views, strings, bool values, |
353 | | // and numeric values. |
354 | | // |
355 | | // Don't use `StrCat()` for user-visible strings. The localization process |
356 | | // works poorly on strings built up out of fragments. |
357 | | // |
358 | | // For clarity and performance, don't use `StrCat()` when appending to a |
359 | | // string. Use `StrAppend()` instead. In particular, avoid using any of these |
360 | | // (anti-)patterns: |
361 | | // |
362 | | // str.append(StrCat(...)) |
363 | | // str += StrCat(...) |
364 | | // str = StrCat(str, ...) |
365 | | // |
366 | | // The last case is the worst, with a potential to change a loop |
367 | | // from a linear time operation with O(1) dynamic allocations into a |
368 | | // quadratic time operation with O(n) dynamic allocations. |
369 | | // |
370 | | // See `StrAppend()` below for more information. |
371 | | |
372 | | namespace strings_internal { |
373 | | |
374 | | // Do not call directly - this is not part of the public API. |
375 | | std::string CatPieces(std::initializer_list<absl::string_view> pieces); |
376 | | void AppendPieces(std::string* dest, |
377 | | std::initializer_list<absl::string_view> pieces); |
378 | | |
379 | | } // namespace strings_internal |
380 | | |
381 | 0 | ABSL_MUST_USE_RESULT inline std::string StrCat() { return std::string(); } |
382 | | |
383 | 0 | ABSL_MUST_USE_RESULT inline std::string StrCat(const AlphaNum& a) { |
384 | 0 | return std::string(a.data(), a.size()); |
385 | 0 | } |
386 | | |
387 | | ABSL_MUST_USE_RESULT std::string StrCat(const AlphaNum& a, const AlphaNum& b); |
388 | | ABSL_MUST_USE_RESULT std::string StrCat(const AlphaNum& a, const AlphaNum& b, |
389 | | const AlphaNum& c); |
390 | | ABSL_MUST_USE_RESULT std::string StrCat(const AlphaNum& a, const AlphaNum& b, |
391 | | const AlphaNum& c, const AlphaNum& d); |
392 | | |
393 | | // Support 5 or more arguments |
394 | | template <typename... AV> |
395 | | ABSL_MUST_USE_RESULT inline std::string StrCat( |
396 | | const AlphaNum& a, const AlphaNum& b, const AlphaNum& c, const AlphaNum& d, |
397 | | const AlphaNum& e, const AV&... args) { |
398 | | return strings_internal::CatPieces( |
399 | | {a.Piece(), b.Piece(), c.Piece(), d.Piece(), e.Piece(), |
400 | | static_cast<const AlphaNum&>(args).Piece()...}); |
401 | | } |
402 | | |
403 | | // ----------------------------------------------------------------------------- |
404 | | // StrAppend() |
405 | | // ----------------------------------------------------------------------------- |
406 | | // |
407 | | // Appends a string or set of strings to an existing string, in a similar |
408 | | // fashion to `StrCat()`. |
409 | | // |
410 | | // WARNING: `StrAppend(&str, a, b, c, ...)` requires that none of the |
411 | | // a, b, c, parameters be a reference into str. For speed, `StrAppend()` does |
412 | | // not try to check each of its input arguments to be sure that they are not |
413 | | // a subset of the string being appended to. That is, while this will work: |
414 | | // |
415 | | // std::string s = "foo"; |
416 | | // s += s; |
417 | | // |
418 | | // This output is undefined: |
419 | | // |
420 | | // std::string s = "foo"; |
421 | | // StrAppend(&s, s); |
422 | | // |
423 | | // This output is undefined as well, since `absl::string_view` does not own its |
424 | | // data: |
425 | | // |
426 | | // std::string s = "foobar"; |
427 | | // absl::string_view p = s; |
428 | | // StrAppend(&s, p); |
429 | | |
430 | 0 | inline void StrAppend(std::string*) {} |
431 | | void StrAppend(std::string* dest, const AlphaNum& a); |
432 | | void StrAppend(std::string* dest, const AlphaNum& a, const AlphaNum& b); |
433 | | void StrAppend(std::string* dest, const AlphaNum& a, const AlphaNum& b, |
434 | | const AlphaNum& c); |
435 | | void StrAppend(std::string* dest, const AlphaNum& a, const AlphaNum& b, |
436 | | const AlphaNum& c, const AlphaNum& d); |
437 | | |
438 | | // Support 5 or more arguments |
439 | | template <typename... AV> |
440 | | inline void StrAppend(std::string* dest, const AlphaNum& a, const AlphaNum& b, |
441 | | const AlphaNum& c, const AlphaNum& d, const AlphaNum& e, |
442 | | const AV&... args) { |
443 | | strings_internal::AppendPieces( |
444 | | dest, {a.Piece(), b.Piece(), c.Piece(), d.Piece(), e.Piece(), |
445 | | static_cast<const AlphaNum&>(args).Piece()...}); |
446 | | } |
447 | | |
448 | | // Helper function for the future StrCat default floating-point format, %.6g |
449 | | // This is fast. |
450 | | inline strings_internal::AlphaNumBuffer< |
451 | | numbers_internal::kSixDigitsToBufferSize> |
452 | 0 | SixDigits(double d) { |
453 | 0 | strings_internal::AlphaNumBuffer<numbers_internal::kSixDigitsToBufferSize> |
454 | 0 | result; |
455 | 0 | result.size = numbers_internal::SixDigitsToBuffer(d, &result.data[0]); |
456 | 0 | return result; |
457 | 0 | } |
458 | | |
459 | | ABSL_NAMESPACE_END |
460 | | } // namespace absl |
461 | | |
462 | | #endif // ABSL_STRINGS_STR_CAT_H_ |