1// 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#ifndef BASE_STRINGS_STRING_PIECE_H_
23#define BASE_STRINGS_STRING_PIECE_H_
24
25#include <stddef.h>
26
27#include <iosfwd>
28#include <string>
29
30#include "base/base_export.h"
31#include "base/containers/hash_tables.h"
32#include "base/logging.h"
33#include "base/strings/string16.h"
34
35namespace base {
36
37template <typename STRING_TYPE> class BasicStringPiece;
38typedef BasicStringPiece<std::string> StringPiece;
39typedef BasicStringPiece<string16> StringPiece16;
40
41// internal --------------------------------------------------------------------
42
43// Many of the StringPiece functions use different implementations for the
44// 8-bit and 16-bit versions, and we don't want lots of template expansions in
45// this (very common) header that will slow down compilation.
46//
47// So here we define overloaded functions called by the StringPiece template.
48// For those that share an implementation, the two versions will expand to a
49// template internal to the .cc file.
50namespace internal {
51
52BASE_EXPORT void CopyToString(const StringPiece& self, std::string* target);
53BASE_EXPORT void CopyToString(const StringPiece16& self, string16* target);
54
55BASE_EXPORT void AppendToString(const StringPiece& self, std::string* target);
56BASE_EXPORT void AppendToString(const StringPiece16& self, string16* target);
57
58BASE_EXPORT size_t copy(const StringPiece& self,
59                        char* buf,
60                        size_t n,
61                        size_t pos);
62BASE_EXPORT size_t copy(const StringPiece16& self,
63                        char16* buf,
64                        size_t n,
65                        size_t pos);
66
67BASE_EXPORT size_t find(const StringPiece& self,
68                        const StringPiece& s,
69                        size_t pos);
70BASE_EXPORT size_t find(const StringPiece16& self,
71                        const StringPiece16& s,
72                        size_t pos);
73BASE_EXPORT size_t find(const StringPiece& self,
74                        char c,
75                        size_t pos);
76BASE_EXPORT size_t find(const StringPiece16& self,
77                        char16 c,
78                        size_t pos);
79
80BASE_EXPORT size_t rfind(const StringPiece& self,
81                         const StringPiece& s,
82                         size_t pos);
83BASE_EXPORT size_t rfind(const StringPiece16& self,
84                         const StringPiece16& s,
85                         size_t pos);
86BASE_EXPORT size_t rfind(const StringPiece& self,
87                         char c,
88                         size_t pos);
89BASE_EXPORT size_t rfind(const StringPiece16& self,
90                         char16 c,
91                         size_t pos);
92
93BASE_EXPORT size_t find_first_of(const StringPiece& self,
94                                 const StringPiece& s,
95                                 size_t pos);
96BASE_EXPORT size_t find_first_of(const StringPiece16& self,
97                                 const StringPiece16& s,
98                                 size_t pos);
99
100BASE_EXPORT size_t find_first_not_of(const StringPiece& self,
101                                     const StringPiece& s,
102                                     size_t pos);
103BASE_EXPORT size_t find_first_not_of(const StringPiece16& self,
104                                     const StringPiece16& s,
105                                     size_t pos);
106BASE_EXPORT size_t find_first_not_of(const StringPiece& self,
107                                     char c,
108                                     size_t pos);
109BASE_EXPORT size_t find_first_not_of(const StringPiece16& self,
110                                     char16 c,
111                                     size_t pos);
112
113BASE_EXPORT size_t find_last_of(const StringPiece& self,
114                                const StringPiece& s,
115                                size_t pos);
116BASE_EXPORT size_t find_last_of(const StringPiece16& self,
117                                const StringPiece16& s,
118                                size_t pos);
119BASE_EXPORT size_t find_last_of(const StringPiece& self,
120                                char c,
121                                size_t pos);
122BASE_EXPORT size_t find_last_of(const StringPiece16& self,
123                                char16 c,
124                                size_t pos);
125
126BASE_EXPORT size_t find_last_not_of(const StringPiece& self,
127                                    const StringPiece& s,
128                                    size_t pos);
129BASE_EXPORT size_t find_last_not_of(const StringPiece16& self,
130                                    const StringPiece16& s,
131                                    size_t pos);
132BASE_EXPORT size_t find_last_not_of(const StringPiece16& self,
133                                    char16 c,
134                                    size_t pos);
135BASE_EXPORT size_t find_last_not_of(const StringPiece& self,
136                                    char c,
137                                    size_t pos);
138
139BASE_EXPORT StringPiece substr(const StringPiece& self,
140                               size_t pos,
141                               size_t n);
142BASE_EXPORT StringPiece16 substr(const StringPiece16& self,
143                                 size_t pos,
144                                 size_t n);
145
146#if DCHECK_IS_ON()
147// Asserts that begin <= end to catch some errors with iterator usage.
148BASE_EXPORT void AssertIteratorsInOrder(std::string::const_iterator begin,
149                                        std::string::const_iterator end);
150BASE_EXPORT void AssertIteratorsInOrder(string16::const_iterator begin,
151                                        string16::const_iterator end);
152#endif
153
154}  // namespace internal
155
156// BasicStringPiece ------------------------------------------------------------
157
158// Defines the types, methods, operators, and data members common to both
159// StringPiece and StringPiece16. Do not refer to this class directly, but
160// rather to BasicStringPiece, StringPiece, or StringPiece16.
161//
162// This is templatized by string class type rather than character type, so
163// BasicStringPiece<std::string> or BasicStringPiece<base::string16>.
164template <typename STRING_TYPE> class BasicStringPiece {
165 public:
166  // Standard STL container boilerplate.
167  typedef size_t size_type;
168  typedef typename STRING_TYPE::value_type value_type;
169  typedef const value_type* pointer;
170  typedef const value_type& reference;
171  typedef const value_type& const_reference;
172  typedef ptrdiff_t difference_type;
173  typedef const value_type* const_iterator;
174  typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
175
176  static const size_type npos;
177
178 public:
179  // We provide non-explicit singleton constructors so users can pass
180  // in a "const char*" or a "string" wherever a "StringPiece" is
181  // expected (likewise for char16, string16, StringPiece16).
182  BasicStringPiece() : ptr_(NULL), length_(0) {}
183  BasicStringPiece(const value_type* str)
184      : ptr_(str),
185        length_((str == NULL) ? 0 : STRING_TYPE::traits_type::length(str)) {}
186  BasicStringPiece(const STRING_TYPE& str)
187      : ptr_(str.data()), length_(str.size()) {}
188  BasicStringPiece(const value_type* offset, size_type len)
189      : ptr_(offset), length_(len) {}
190  BasicStringPiece(const typename STRING_TYPE::const_iterator& begin,
191                   const typename STRING_TYPE::const_iterator& end) {
192#if DCHECK_IS_ON()
193    // This assertion is done out-of-line to avoid bringing in logging.h and
194    // instantiating logging macros for every instantiation.
195    internal::AssertIteratorsInOrder(begin, end);
196#endif
197    length_ = static_cast<size_t>(std::distance(begin, end));
198
199    // The length test before assignment is to avoid dereferencing an iterator
200    // that may point to the end() of a string.
201    ptr_ = length_ > 0 ? &*begin : nullptr;
202  }
203
204  // data() may return a pointer to a buffer with embedded NULs, and the
205  // returned buffer may or may not be null terminated.  Therefore it is
206  // typically a mistake to pass data() to a routine that expects a NUL
207  // terminated string.
208  const value_type* data() const { return ptr_; }
209  size_type size() const { return length_; }
210  size_type length() const { return length_; }
211  bool empty() const { return length_ == 0; }
212
213  void clear() {
214    ptr_ = NULL;
215    length_ = 0;
216  }
217  void set(const value_type* data, size_type len) {
218    ptr_ = data;
219    length_ = len;
220  }
221  void set(const value_type* str) {
222    ptr_ = str;
223    length_ = str ? STRING_TYPE::traits_type::length(str) : 0;
224  }
225
226  value_type operator[](size_type i) const { return ptr_[i]; }
227
228  void remove_prefix(size_type n) {
229    ptr_ += n;
230    length_ -= n;
231  }
232
233  void remove_suffix(size_type n) {
234    length_ -= n;
235  }
236
237  int compare(const BasicStringPiece<STRING_TYPE>& x) const {
238    int r = wordmemcmp(
239        ptr_, x.ptr_, (length_ < x.length_ ? length_ : x.length_));
240    if (r == 0) {
241      if (length_ < x.length_) r = -1;
242      else if (length_ > x.length_) r = +1;
243    }
244    return r;
245  }
246
247  STRING_TYPE as_string() const {
248    // std::string doesn't like to take a NULL pointer even with a 0 size.
249    return empty() ? STRING_TYPE() : STRING_TYPE(data(), size());
250  }
251
252  const_iterator begin() const { return ptr_; }
253  const_iterator end() const { return ptr_ + length_; }
254  const_reverse_iterator rbegin() const {
255    return const_reverse_iterator(ptr_ + length_);
256  }
257  const_reverse_iterator rend() const {
258    return const_reverse_iterator(ptr_);
259  }
260
261  size_type max_size() const { return length_; }
262  size_type capacity() const { return length_; }
263
264  static int wordmemcmp(const value_type* p,
265                        const value_type* p2,
266                        size_type N) {
267    return STRING_TYPE::traits_type::compare(p, p2, N);
268  }
269
270  // Sets the value of the given string target type to be the current string.
271  // This saves a temporary over doing |a = b.as_string()|
272  void CopyToString(STRING_TYPE* target) const {
273    internal::CopyToString(*this, target);
274  }
275
276  void AppendToString(STRING_TYPE* target) const {
277    internal::AppendToString(*this, target);
278  }
279
280  size_type copy(value_type* buf, size_type n, size_type pos = 0) const {
281    return internal::copy(*this, buf, n, pos);
282  }
283
284  // Does "this" start with "x"
285  bool starts_with(const BasicStringPiece& x) const {
286    return ((this->length_ >= x.length_) &&
287            (wordmemcmp(this->ptr_, x.ptr_, x.length_) == 0));
288  }
289
290  // Does "this" end with "x"
291  bool ends_with(const BasicStringPiece& x) const {
292    return ((this->length_ >= x.length_) &&
293            (wordmemcmp(this->ptr_ + (this->length_-x.length_),
294                        x.ptr_, x.length_) == 0));
295  }
296
297  // find: Search for a character or substring at a given offset.
298  size_type find(const BasicStringPiece<STRING_TYPE>& s,
299                 size_type pos = 0) const {
300    return internal::find(*this, s, pos);
301  }
302  size_type find(value_type c, size_type pos = 0) const {
303    return internal::find(*this, c, pos);
304  }
305
306  // rfind: Reverse find.
307  size_type rfind(const BasicStringPiece& s,
308                  size_type pos = BasicStringPiece::npos) const {
309    return internal::rfind(*this, s, pos);
310  }
311  size_type rfind(value_type c, size_type pos = BasicStringPiece::npos) const {
312    return internal::rfind(*this, c, pos);
313  }
314
315  // find_first_of: Find the first occurence of one of a set of characters.
316  size_type find_first_of(const BasicStringPiece& s,
317                          size_type pos = 0) const {
318    return internal::find_first_of(*this, s, pos);
319  }
320  size_type find_first_of(value_type c, size_type pos = 0) const {
321    return find(c, pos);
322  }
323
324  // find_first_not_of: Find the first occurence not of a set of characters.
325  size_type find_first_not_of(const BasicStringPiece& s,
326                              size_type pos = 0) const {
327    return internal::find_first_not_of(*this, s, pos);
328  }
329  size_type find_first_not_of(value_type c, size_type pos = 0) const {
330    return internal::find_first_not_of(*this, c, pos);
331  }
332
333  // find_last_of: Find the last occurence of one of a set of characters.
334  size_type find_last_of(const BasicStringPiece& s,
335                         size_type pos = BasicStringPiece::npos) const {
336    return internal::find_last_of(*this, s, pos);
337  }
338  size_type find_last_of(value_type c,
339                         size_type pos = BasicStringPiece::npos) const {
340    return rfind(c, pos);
341  }
342
343  // find_last_not_of: Find the last occurence not of a set of characters.
344  size_type find_last_not_of(const BasicStringPiece& s,
345                             size_type pos = BasicStringPiece::npos) const {
346    return internal::find_last_not_of(*this, s, pos);
347  }
348  size_type find_last_not_of(value_type c,
349                             size_type pos = BasicStringPiece::npos) const {
350    return internal::find_last_not_of(*this, c, pos);
351  }
352
353  // substr.
354  BasicStringPiece substr(size_type pos,
355                          size_type n = BasicStringPiece::npos) const {
356    return internal::substr(*this, pos, n);
357  }
358
359 protected:
360  const value_type* ptr_;
361  size_type     length_;
362};
363
364template <typename STRING_TYPE>
365const typename BasicStringPiece<STRING_TYPE>::size_type
366BasicStringPiece<STRING_TYPE>::npos =
367    typename BasicStringPiece<STRING_TYPE>::size_type(-1);
368
369// MSVC doesn't like complex extern templates and DLLs.
370#if !defined(COMPILER_MSVC)
371extern template class BASE_EXPORT BasicStringPiece<std::string>;
372extern template class BASE_EXPORT BasicStringPiece<string16>;
373#endif
374
375// StingPiece operators --------------------------------------------------------
376
377BASE_EXPORT bool operator==(const StringPiece& x, const StringPiece& y);
378
379inline bool operator!=(const StringPiece& x, const StringPiece& y) {
380  return !(x == y);
381}
382
383inline bool operator<(const StringPiece& x, const StringPiece& y) {
384  const int r = StringPiece::wordmemcmp(
385      x.data(), y.data(), (x.size() < y.size() ? x.size() : y.size()));
386  return ((r < 0) || ((r == 0) && (x.size() < y.size())));
387}
388
389inline bool operator>(const StringPiece& x, const StringPiece& y) {
390  return y < x;
391}
392
393inline bool operator<=(const StringPiece& x, const StringPiece& y) {
394  return !(x > y);
395}
396
397inline bool operator>=(const StringPiece& x, const StringPiece& y) {
398  return !(x < y);
399}
400
401// StringPiece16 operators -----------------------------------------------------
402
403inline bool operator==(const StringPiece16& x, const StringPiece16& y) {
404  if (x.size() != y.size())
405    return false;
406
407  return StringPiece16::wordmemcmp(x.data(), y.data(), x.size()) == 0;
408}
409
410inline bool operator!=(const StringPiece16& x, const StringPiece16& y) {
411  return !(x == y);
412}
413
414inline bool operator<(const StringPiece16& x, const StringPiece16& y) {
415  const int r = StringPiece16::wordmemcmp(
416      x.data(), y.data(), (x.size() < y.size() ? x.size() : y.size()));
417  return ((r < 0) || ((r == 0) && (x.size() < y.size())));
418}
419
420inline bool operator>(const StringPiece16& x, const StringPiece16& y) {
421  return y < x;
422}
423
424inline bool operator<=(const StringPiece16& x, const StringPiece16& y) {
425  return !(x > y);
426}
427
428inline bool operator>=(const StringPiece16& x, const StringPiece16& y) {
429  return !(x < y);
430}
431
432BASE_EXPORT std::ostream& operator<<(std::ostream& o,
433                                     const StringPiece& piece);
434
435}  // namespace base
436
437// Hashing ---------------------------------------------------------------------
438
439// We provide appropriate hash functions so StringPiece and StringPiece16 can
440// be used as keys in hash sets and maps.
441
442// This hash function is copied from base/containers/hash_tables.h. We don't
443// use the ones already defined for string and string16 directly because it
444// would require the string constructors to be called, which we don't want.
445#define HASH_STRING_PIECE(StringPieceType, string_piece)                \
446  std::size_t result = 0;                                               \
447  for (StringPieceType::const_iterator i = string_piece.begin();        \
448       i != string_piece.end(); ++i)                                    \
449    result = (result * 131) + *i;                                       \
450  return result;                                                        \
451
452namespace BASE_HASH_NAMESPACE {
453
454template<>
455struct hash<base::StringPiece> {
456  std::size_t operator()(const base::StringPiece& sp) const {
457    HASH_STRING_PIECE(base::StringPiece, sp);
458  }
459};
460template<>
461struct hash<base::StringPiece16> {
462  std::size_t operator()(const base::StringPiece16& sp16) const {
463    HASH_STRING_PIECE(base::StringPiece16, sp16);
464  }
465};
466
467}  // namespace BASE_HASH_NAMESPACE
468
469#endif  // BASE_STRINGS_STRING_PIECE_H_
470