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James Robinson646469d2014-10-03 15:33:28 -07001// Copyright (c) 2012 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4// Copied from strings/stringpiece.h with modifications
5//
6// A string-like object that points to a sized piece of memory.
7//
8// You can use StringPiece as a function or method parameter. A StringPiece
9// parameter can receive a double-quoted string literal argument, a "const
10// char*" argument, a string argument, or a StringPiece argument with no data
11// copying. Systematic use of StringPiece for arguments reduces data
12// copies and strlen() calls.
13//
14// Prefer passing StringPieces by value:
15// void MyFunction(StringPiece arg);
16// If circumstances require, you may also pass by const reference:
17// void MyFunction(const StringPiece& arg); // not preferred
18// Both of these have the same lifetime semantics. Passing by value
19// generates slightly smaller code. For more discussion, Googlers can see
20// the thread go/stringpiecebyvalue on c-users.
21//
22// StringPiece16 is similar to StringPiece but for base::string16 instead of
23// std::string. We do not define as large of a subset of the STL functions
24// from basic_string as in StringPiece, but this can be changed if these
25// functions (find, find_first_of, etc.) are found to be useful in this context.
26//
27
28#ifndef BASE_STRINGS_STRING_PIECE_H_
29#define BASE_STRINGS_STRING_PIECE_H_
30
31#include <stddef.h>
32
33#include <iosfwd>
34#include <string>
35
36#include "base/base_export.h"
37#include "base/basictypes.h"
38#include "base/containers/hash_tables.h"
39#include "base/strings/string16.h"
40
41namespace base {
42
43template <typename STRING_TYPE> class BasicStringPiece;
44typedef BasicStringPiece<std::string> StringPiece;
45typedef BasicStringPiece<string16> StringPiece16;
46
47// internal --------------------------------------------------------------------
48
49// Many of the StringPiece functions use different implementations for the
50// 8-bit and 16-bit versions, and we don't want lots of template expansions in
51// this (very common) header that will slow down compilation.
52//
53// So here we define overloaded functions called by the StringPiece template.
54// For those that share an implementation, the two versions will expand to a
55// template internal to the .cc file.
56namespace internal {
57
58BASE_EXPORT void CopyToString(const StringPiece& self, std::string* target);
59BASE_EXPORT void CopyToString(const StringPiece16& self, string16* target);
60
61BASE_EXPORT void AppendToString(const StringPiece& self, std::string* target);
62BASE_EXPORT void AppendToString(const StringPiece16& self, string16* target);
63
64BASE_EXPORT size_t copy(const StringPiece& self,
65 char* buf,
66 size_t n,
67 size_t pos);
68BASE_EXPORT size_t copy(const StringPiece16& self,
69 char16* buf,
70 size_t n,
71 size_t pos);
72
73BASE_EXPORT size_t find(const StringPiece& self,
74 const StringPiece& s,
75 size_t pos);
76BASE_EXPORT size_t find(const StringPiece16& self,
77 const StringPiece16& s,
78 size_t pos);
79BASE_EXPORT size_t find(const StringPiece& self,
80 char c,
81 size_t pos);
82BASE_EXPORT size_t find(const StringPiece16& self,
83 char16 c,
84 size_t pos);
85
86BASE_EXPORT size_t rfind(const StringPiece& self,
87 const StringPiece& s,
88 size_t pos);
89BASE_EXPORT size_t rfind(const StringPiece16& self,
90 const StringPiece16& s,
91 size_t pos);
92BASE_EXPORT size_t rfind(const StringPiece& self,
93 char c,
94 size_t pos);
95BASE_EXPORT size_t rfind(const StringPiece16& self,
96 char16 c,
97 size_t pos);
98
99BASE_EXPORT size_t find_first_of(const StringPiece& self,
100 const StringPiece& s,
101 size_t pos);
102BASE_EXPORT size_t find_first_of(const StringPiece16& self,
103 const StringPiece16& s,
104 size_t pos);
105
106BASE_EXPORT size_t find_first_not_of(const StringPiece& self,
107 const StringPiece& s,
108 size_t pos);
109BASE_EXPORT size_t find_first_not_of(const StringPiece16& self,
110 const StringPiece16& s,
111 size_t pos);
112BASE_EXPORT size_t find_first_not_of(const StringPiece& self,
113 char c,
114 size_t pos);
115BASE_EXPORT size_t find_first_not_of(const StringPiece16& self,
116 char16 c,
117 size_t pos);
118
119BASE_EXPORT size_t find_last_of(const StringPiece& self,
120 const StringPiece& s,
121 size_t pos);
122BASE_EXPORT size_t find_last_of(const StringPiece16& self,
123 const StringPiece16& s,
124 size_t pos);
125BASE_EXPORT size_t find_last_of(const StringPiece& self,
126 char c,
127 size_t pos);
128BASE_EXPORT size_t find_last_of(const StringPiece16& self,
129 char16 c,
130 size_t pos);
131
132BASE_EXPORT size_t find_last_not_of(const StringPiece& self,
133 const StringPiece& s,
134 size_t pos);
135BASE_EXPORT size_t find_last_not_of(const StringPiece16& self,
136 const StringPiece16& s,
137 size_t pos);
138BASE_EXPORT size_t find_last_not_of(const StringPiece16& self,
139 char16 c,
140 size_t pos);
141BASE_EXPORT size_t find_last_not_of(const StringPiece& self,
142 char c,
143 size_t pos);
144
145BASE_EXPORT StringPiece substr(const StringPiece& self,
146 size_t pos,
147 size_t n);
148BASE_EXPORT StringPiece16 substr(const StringPiece16& self,
149 size_t pos,
150 size_t n);
151
152} // namespace internal
153
154// BasicStringPiece ------------------------------------------------------------
155
156// Defines the types, methods, operators, and data members common to both
157// StringPiece and StringPiece16. Do not refer to this class directly, but
158// rather to BasicStringPiece, StringPiece, or StringPiece16.
159//
160// This is templatized by string class type rather than character type, so
161// BasicStringPiece<std::string> or BasicStringPiece<base::string16>.
162template <typename STRING_TYPE> class BasicStringPiece {
163 public:
164 // Standard STL container boilerplate.
165 typedef size_t size_type;
166 typedef typename STRING_TYPE::value_type value_type;
167 typedef const value_type* pointer;
168 typedef const value_type& reference;
169 typedef const value_type& const_reference;
170 typedef ptrdiff_t difference_type;
171 typedef const value_type* const_iterator;
172 typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
173
174 static const size_type npos;
175
176 public:
177 // We provide non-explicit singleton constructors so users can pass
178 // in a "const char*" or a "string" wherever a "StringPiece" is
179 // expected (likewise for char16, string16, StringPiece16).
180 BasicStringPiece() : ptr_(NULL), length_(0) {}
181 BasicStringPiece(const value_type* str)
182 : ptr_(str),
183 length_((str == NULL) ? 0 : STRING_TYPE::traits_type::length(str)) {}
184 BasicStringPiece(const STRING_TYPE& str)
185 : ptr_(str.data()), length_(str.size()) {}
186 BasicStringPiece(const value_type* offset, size_type len)
187 : ptr_(offset), length_(len) {}
188 BasicStringPiece(const typename STRING_TYPE::const_iterator& begin,
189 const typename STRING_TYPE::const_iterator& end)
190 : ptr_((end > begin) ? &(*begin) : NULL),
191 length_((end > begin) ? (size_type)(end - begin) : 0) {}
192
193 // data() may return a pointer to a buffer with embedded NULs, and the
194 // returned buffer may or may not be null terminated. Therefore it is
195 // typically a mistake to pass data() to a routine that expects a NUL
196 // terminated string.
197 const value_type* data() const { return ptr_; }
198 size_type size() const { return length_; }
199 size_type length() const { return length_; }
200 bool empty() const { return length_ == 0; }
201
202 void clear() {
203 ptr_ = NULL;
204 length_ = 0;
205 }
206 void set(const value_type* data, size_type len) {
207 ptr_ = data;
208 length_ = len;
209 }
210 void set(const value_type* str) {
211 ptr_ = str;
212 length_ = str ? STRING_TYPE::traits_type::length(str) : 0;
213 }
214
215 value_type operator[](size_type i) const { return ptr_[i]; }
216
217 void remove_prefix(size_type n) {
218 ptr_ += n;
219 length_ -= n;
220 }
221
222 void remove_suffix(size_type n) {
223 length_ -= n;
224 }
225
226 int compare(const BasicStringPiece<STRING_TYPE>& x) const {
227 int r = wordmemcmp(
228 ptr_, x.ptr_, (length_ < x.length_ ? length_ : x.length_));
229 if (r == 0) {
230 if (length_ < x.length_) r = -1;
231 else if (length_ > x.length_) r = +1;
232 }
233 return r;
234 }
235
236 STRING_TYPE as_string() const {
237 // std::string doesn't like to take a NULL pointer even with a 0 size.
238 return empty() ? STRING_TYPE() : STRING_TYPE(data(), size());
239 }
240
241 const_iterator begin() const { return ptr_; }
242 const_iterator end() const { return ptr_ + length_; }
243 const_reverse_iterator rbegin() const {
244 return const_reverse_iterator(ptr_ + length_);
245 }
246 const_reverse_iterator rend() const {
247 return const_reverse_iterator(ptr_);
248 }
249
250 size_type max_size() const { return length_; }
251 size_type capacity() const { return length_; }
252
253 static int wordmemcmp(const value_type* p,
254 const value_type* p2,
255 size_type N) {
256 return STRING_TYPE::traits_type::compare(p, p2, N);
257 }
258
259 // Sets the value of the given string target type to be the current string.
260 // This saves a temporary over doing |a = b.as_string()|
261 void CopyToString(STRING_TYPE* target) const {
262 internal::CopyToString(*this, target);
263 }
264
265 void AppendToString(STRING_TYPE* target) const {
266 internal::AppendToString(*this, target);
267 }
268
269 size_type copy(value_type* buf, size_type n, size_type pos = 0) const {
270 return internal::copy(*this, buf, n, pos);
271 }
272
273 // Does "this" start with "x"
274 bool starts_with(const BasicStringPiece& x) const {
275 return ((this->length_ >= x.length_) &&
276 (wordmemcmp(this->ptr_, x.ptr_, x.length_) == 0));
277 }
278
279 // Does "this" end with "x"
280 bool ends_with(const BasicStringPiece& x) const {
281 return ((this->length_ >= x.length_) &&
282 (wordmemcmp(this->ptr_ + (this->length_-x.length_),
283 x.ptr_, x.length_) == 0));
284 }
285
286 // find: Search for a character or substring at a given offset.
287 size_type find(const BasicStringPiece<STRING_TYPE>& s,
288 size_type pos = 0) const {
289 return internal::find(*this, s, pos);
290 }
291 size_type find(value_type c, size_type pos = 0) const {
292 return internal::find(*this, c, pos);
293 }
294
295 // rfind: Reverse find.
296 size_type rfind(const BasicStringPiece& s,
297 size_type pos = BasicStringPiece::npos) const {
298 return internal::rfind(*this, s, pos);
299 }
300 size_type rfind(value_type c, size_type pos = BasicStringPiece::npos) const {
301 return internal::rfind(*this, c, pos);
302 }
303
304 // find_first_of: Find the first occurence of one of a set of characters.
305 size_type find_first_of(const BasicStringPiece& s,
306 size_type pos = 0) const {
307 return internal::find_first_of(*this, s, pos);
308 }
309 size_type find_first_of(value_type c, size_type pos = 0) const {
310 return find(c, pos);
311 }
312
313 // find_first_not_of: Find the first occurence not of a set of characters.
314 size_type find_first_not_of(const BasicStringPiece& s,
315 size_type pos = 0) const {
316 return internal::find_first_not_of(*this, s, pos);
317 }
318 size_type find_first_not_of(value_type c, size_type pos = 0) const {
319 return internal::find_first_not_of(*this, c, pos);
320 }
321
322 // find_last_of: Find the last occurence of one of a set of characters.
323 size_type find_last_of(const BasicStringPiece& s,
324 size_type pos = BasicStringPiece::npos) const {
325 return internal::find_last_of(*this, s, pos);
326 }
327 size_type find_last_of(value_type c,
328 size_type pos = BasicStringPiece::npos) const {
329 return rfind(c, pos);
330 }
331
332 // find_last_not_of: Find the last occurence not of a set of characters.
333 size_type find_last_not_of(const BasicStringPiece& s,
334 size_type pos = BasicStringPiece::npos) const {
335 return internal::find_last_not_of(*this, s, pos);
336 }
337 size_type find_last_not_of(value_type c,
338 size_type pos = BasicStringPiece::npos) const {
339 return internal::find_last_not_of(*this, c, pos);
340 }
341
342 // substr.
343 BasicStringPiece substr(size_type pos,
344 size_type n = BasicStringPiece::npos) const {
345 return internal::substr(*this, pos, n);
346 }
347
348 protected:
349 const value_type* ptr_;
350 size_type length_;
351};
352
353template <typename STRING_TYPE>
354const typename BasicStringPiece<STRING_TYPE>::size_type
355BasicStringPiece<STRING_TYPE>::npos =
356 typename BasicStringPiece<STRING_TYPE>::size_type(-1);
357
358// MSVC doesn't like complex extern templates and DLLs.
359#if !defined(COMPILER_MSVC)
360extern template class BASE_EXPORT BasicStringPiece<std::string>;
361extern template class BASE_EXPORT BasicStringPiece<string16>;
362#endif
363
364// StingPiece operators --------------------------------------------------------
365
366BASE_EXPORT bool operator==(const StringPiece& x, const StringPiece& y);
367
368inline bool operator!=(const StringPiece& x, const StringPiece& y) {
369 return !(x == y);
370}
371
372inline bool operator<(const StringPiece& x, const StringPiece& y) {
373 const int r = StringPiece::wordmemcmp(
374 x.data(), y.data(), (x.size() < y.size() ? x.size() : y.size()));
375 return ((r < 0) || ((r == 0) && (x.size() < y.size())));
376}
377
378inline bool operator>(const StringPiece& x, const StringPiece& y) {
379 return y < x;
380}
381
382inline bool operator<=(const StringPiece& x, const StringPiece& y) {
383 return !(x > y);
384}
385
386inline bool operator>=(const StringPiece& x, const StringPiece& y) {
387 return !(x < y);
388}
389
390// StringPiece16 operators -----------------------------------------------------
391
392inline bool operator==(const StringPiece16& x, const StringPiece16& y) {
393 if (x.size() != y.size())
394 return false;
395
396 return StringPiece16::wordmemcmp(x.data(), y.data(), x.size()) == 0;
397}
398
399inline bool operator!=(const StringPiece16& x, const StringPiece16& y) {
400 return !(x == y);
401}
402
403inline bool operator<(const StringPiece16& x, const StringPiece16& y) {
404 const int r = StringPiece16::wordmemcmp(
405 x.data(), y.data(), (x.size() < y.size() ? x.size() : y.size()));
406 return ((r < 0) || ((r == 0) && (x.size() < y.size())));
407}
408
409inline bool operator>(const StringPiece16& x, const StringPiece16& y) {
410 return y < x;
411}
412
413inline bool operator<=(const StringPiece16& x, const StringPiece16& y) {
414 return !(x > y);
415}
416
417inline bool operator>=(const StringPiece16& x, const StringPiece16& y) {
418 return !(x < y);
419}
420
421BASE_EXPORT std::ostream& operator<<(std::ostream& o,
422 const StringPiece& piece);
423
424} // namespace base
425
426// Hashing ---------------------------------------------------------------------
427
428// We provide appropriate hash functions so StringPiece and StringPiece16 can
429// be used as keys in hash sets and maps.
430
431// This hash function is copied from base/containers/hash_tables.h. We don't
432// use the ones already defined for string and string16 directly because it
433// would require the string constructors to be called, which we don't want.
434#define HASH_STRING_PIECE(StringPieceType, string_piece) \
435 std::size_t result = 0; \
436 for (StringPieceType::const_iterator i = string_piece.begin(); \
437 i != string_piece.end(); ++i) \
438 result = (result * 131) + *i; \
439 return result; \
440
441namespace BASE_HASH_NAMESPACE {
James Robinson646469d2014-10-03 15:33:28 -0700442
443template<>
444struct hash<base::StringPiece> {
445 std::size_t operator()(const base::StringPiece& sp) const {
446 HASH_STRING_PIECE(base::StringPiece, sp);
447 }
448};
449template<>
450struct hash<base::StringPiece16> {
451 std::size_t operator()(const base::StringPiece16& sp16) const {
452 HASH_STRING_PIECE(base::StringPiece16, sp16);
453 }
454};
455
James Robinson646469d2014-10-03 15:33:28 -0700456} // namespace BASE_HASH_NAMESPACE
457
458#endif // BASE_STRINGS_STRING_PIECE_H_