Btk
core.h
1 // Copyright 2006 Nemanja Trifunovic
2 
3 /*
4 Permission is hereby granted, free of charge, to any person or organization
5 obtaining a copy of the software and accompanying documentation covered by
6 this license (the "Software") to use, reproduce, display, distribute,
7 execute, and transmit the Software, and to prepare derivative works of the
8 Software, and to permit third-parties to whom the Software is furnished to
9 do so, all subject to the following:
10 
11 The copyright notices in the Software and this entire statement, including
12 the above license grant, this restriction and the following disclaimer,
13 must be included in all copies of the Software, in whole or in part, and
14 all derivative works of the Software, unless such copies or derivative
15 works are solely in the form of machine-executable object code generated by
16 a source language processor.
17 
18 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
19 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
20 FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
21 SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
22 FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
23 ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
24 DEALINGS IN THE SOFTWARE.
25 */
26 
27 
28 #ifndef UTF8_FOR_CPP_CORE_H_2675DCD0_9480_4c0c_B92A_CC14C027B731
29 #define UTF8_FOR_CPP_CORE_H_2675DCD0_9480_4c0c_B92A_CC14C027B731
30 
31 #include <iterator>
32 
33 // Determine the C++ standard version.
34 // If the user defines UTF_CPP_CPLUSPLUS, use that.
35 // Otherwise, trust the unreliable predefined macro __cplusplus
36 
37 #if !defined UTF_CPP_CPLUSPLUS
38  #define UTF_CPP_CPLUSPLUS __cplusplus
39 #endif
40 
41 #if UTF_CPP_CPLUSPLUS >= 201103L // C++ 11 or later
42  #define UTF_CPP_OVERRIDE override
43  #define UTF_CPP_NOEXCEPT noexcept
44 #else // C++ 98/03
45  #define UTF_CPP_OVERRIDE
46  #define UTF_CPP_NOEXCEPT throw()
47 #endif // C++ 11 or later
48 
49 
50 namespace utf8
51 {
52  // The typedefs for 8-bit, 16-bit and 32-bit unsigned integers
53  // You may need to change them to match your system.
54  // These typedefs have the same names as ones from cstdint, or boost/cstdint
55  typedef unsigned char uint8_t;
56  typedef unsigned short uint16_t;
57  typedef unsigned int uint32_t;
58 
59 // Helper code - not intended to be directly called by the library users. May be changed at any time
60 namespace internal
61 {
62  // Unicode constants
63  // Leading (high) surrogates: 0xd800 - 0xdbff
64  // Trailing (low) surrogates: 0xdc00 - 0xdfff
65  const uint16_t LEAD_SURROGATE_MIN = 0xd800u;
66  const uint16_t LEAD_SURROGATE_MAX = 0xdbffu;
67  const uint16_t TRAIL_SURROGATE_MIN = 0xdc00u;
68  const uint16_t TRAIL_SURROGATE_MAX = 0xdfffu;
69  const uint16_t LEAD_OFFSET = 0xd7c0u; // LEAD_SURROGATE_MIN - (0x10000 >> 10)
70  const uint32_t SURROGATE_OFFSET = 0xfca02400u; // 0x10000u - (LEAD_SURROGATE_MIN << 10) - TRAIL_SURROGATE_MIN
71 
72  // Maximum valid value for a Unicode code point
73  const uint32_t CODE_POINT_MAX = 0x0010ffffu;
74 
75  template<typename octet_type>
76  inline uint8_t mask8(octet_type oc)
77  {
78  return static_cast<uint8_t>(0xff & oc);
79  }
80  template<typename u16_type>
81  inline uint16_t mask16(u16_type oc)
82  {
83  return static_cast<uint16_t>(0xffff & oc);
84  }
85  template<typename octet_type>
86  inline bool is_trail(octet_type oc)
87  {
88  return ((utf8::internal::mask8(oc) >> 6) == 0x2);
89  }
90 
91  template <typename u16>
92  inline bool is_lead_surrogate(u16 cp)
93  {
94  return (cp >= LEAD_SURROGATE_MIN && cp <= LEAD_SURROGATE_MAX);
95  }
96 
97  template <typename u16>
98  inline bool is_trail_surrogate(u16 cp)
99  {
100  return (cp >= TRAIL_SURROGATE_MIN && cp <= TRAIL_SURROGATE_MAX);
101  }
102 
103  template <typename u16>
104  inline bool is_surrogate(u16 cp)
105  {
106  return (cp >= LEAD_SURROGATE_MIN && cp <= TRAIL_SURROGATE_MAX);
107  }
108 
109  template <typename u32>
110  inline bool is_code_point_valid(u32 cp)
111  {
112  return (cp <= CODE_POINT_MAX && !utf8::internal::is_surrogate(cp));
113  }
114 
115  template <typename octet_iterator>
116  inline typename std::iterator_traits<octet_iterator>::difference_type
117  sequence_length(octet_iterator lead_it)
118  {
119  uint8_t lead = utf8::internal::mask8(*lead_it);
120  if (lead < 0x80)
121  return 1;
122  else if ((lead >> 5) == 0x6)
123  return 2;
124  else if ((lead >> 4) == 0xe)
125  return 3;
126  else if ((lead >> 3) == 0x1e)
127  return 4;
128  else
129  return 0;
130  }
131 
132  template <typename octet_difference_type>
133  inline bool is_overlong_sequence(uint32_t cp, octet_difference_type length)
134  {
135  if (cp < 0x80) {
136  if (length != 1)
137  return true;
138  }
139  else if (cp < 0x800) {
140  if (length != 2)
141  return true;
142  }
143  else if (cp < 0x10000) {
144  if (length != 3)
145  return true;
146  }
147 
148  return false;
149  }
150 
151  enum utf_error {UTF8_OK, NOT_ENOUGH_ROOM, INVALID_LEAD, INCOMPLETE_SEQUENCE, OVERLONG_SEQUENCE, INVALID_CODE_POINT};
152 
154  template <typename octet_iterator>
155  utf_error increase_safely(octet_iterator& it, octet_iterator end)
156  {
157  if (++it == end)
158  return NOT_ENOUGH_ROOM;
159 
160  if (!utf8::internal::is_trail(*it))
161  return INCOMPLETE_SEQUENCE;
162 
163  return UTF8_OK;
164  }
165 
166  #define UTF8_CPP_INCREASE_AND_RETURN_ON_ERROR(IT, END) {utf_error ret = increase_safely(IT, END); if (ret != UTF8_OK) return ret;}
167 
169  template <typename octet_iterator>
170  utf_error get_sequence_1(octet_iterator& it, octet_iterator end, uint32_t& code_point)
171  {
172  if (it == end)
173  return NOT_ENOUGH_ROOM;
174 
175  code_point = utf8::internal::mask8(*it);
176 
177  return UTF8_OK;
178  }
179 
180  template <typename octet_iterator>
181  utf_error get_sequence_2(octet_iterator& it, octet_iterator end, uint32_t& code_point)
182  {
183  if (it == end)
184  return NOT_ENOUGH_ROOM;
185 
186  code_point = utf8::internal::mask8(*it);
187 
188  UTF8_CPP_INCREASE_AND_RETURN_ON_ERROR(it, end)
189 
190  code_point = ((code_point << 6) & 0x7ff) + ((*it) & 0x3f);
191 
192  return UTF8_OK;
193  }
194 
195  template <typename octet_iterator>
196  utf_error get_sequence_3(octet_iterator& it, octet_iterator end, uint32_t& code_point)
197  {
198  if (it == end)
199  return NOT_ENOUGH_ROOM;
200 
201  code_point = utf8::internal::mask8(*it);
202 
203  UTF8_CPP_INCREASE_AND_RETURN_ON_ERROR(it, end)
204 
205  code_point = ((code_point << 12) & 0xffff) + ((utf8::internal::mask8(*it) << 6) & 0xfff);
206 
207  UTF8_CPP_INCREASE_AND_RETURN_ON_ERROR(it, end)
208 
209  code_point += (*it) & 0x3f;
210 
211  return UTF8_OK;
212  }
213 
214  template <typename octet_iterator>
215  utf_error get_sequence_4(octet_iterator& it, octet_iterator end, uint32_t& code_point)
216  {
217  if (it == end)
218  return NOT_ENOUGH_ROOM;
219 
220  code_point = utf8::internal::mask8(*it);
221 
222  UTF8_CPP_INCREASE_AND_RETURN_ON_ERROR(it, end)
223 
224  code_point = ((code_point << 18) & 0x1fffff) + ((utf8::internal::mask8(*it) << 12) & 0x3ffff);
225 
226  UTF8_CPP_INCREASE_AND_RETURN_ON_ERROR(it, end)
227 
228  code_point += (utf8::internal::mask8(*it) << 6) & 0xfff;
229 
230  UTF8_CPP_INCREASE_AND_RETURN_ON_ERROR(it, end)
231 
232  code_point += (*it) & 0x3f;
233 
234  return UTF8_OK;
235  }
236 
237  #undef UTF8_CPP_INCREASE_AND_RETURN_ON_ERROR
238 
239  template <typename octet_iterator>
240  utf_error validate_next(octet_iterator& it, octet_iterator end, uint32_t& code_point)
241  {
242  if (it == end)
243  return NOT_ENOUGH_ROOM;
244 
245  // Save the original value of it so we can go back in case of failure
246  // Of course, it does not make much sense with i.e. stream iterators
247  octet_iterator original_it = it;
248 
249  uint32_t cp = 0;
250  // Determine the sequence length based on the lead octet
251  typedef typename std::iterator_traits<octet_iterator>::difference_type octet_difference_type;
252  const octet_difference_type length = utf8::internal::sequence_length(it);
253 
254  // Get trail octets and calculate the code point
255  utf_error err = UTF8_OK;
256  switch (length) {
257  case 0:
258  return INVALID_LEAD;
259  case 1:
260  err = utf8::internal::get_sequence_1(it, end, cp);
261  break;
262  case 2:
263  err = utf8::internal::get_sequence_2(it, end, cp);
264  break;
265  case 3:
266  err = utf8::internal::get_sequence_3(it, end, cp);
267  break;
268  case 4:
269  err = utf8::internal::get_sequence_4(it, end, cp);
270  break;
271  }
272 
273  if (err == UTF8_OK) {
274  // Decoding succeeded. Now, security checks...
275  if (utf8::internal::is_code_point_valid(cp)) {
276  if (!utf8::internal::is_overlong_sequence(cp, length)){
277  // Passed! Return here.
278  code_point = cp;
279  ++it;
280  return UTF8_OK;
281  }
282  else
283  err = OVERLONG_SEQUENCE;
284  }
285  else
286  err = INVALID_CODE_POINT;
287  }
288 
289  // Failure branch - restore the original value of the iterator
290  it = original_it;
291  return err;
292  }
293 
294  template <typename octet_iterator>
295  inline utf_error validate_next(octet_iterator& it, octet_iterator end) {
296  uint32_t ignored;
297  return utf8::internal::validate_next(it, end, ignored);
298  }
299 
300 } // namespace internal
301 
303 
304  // Byte order mark
305  const uint8_t bom[] = {0xef, 0xbb, 0xbf};
306 
307  template <typename octet_iterator>
308  octet_iterator find_invalid(octet_iterator start, octet_iterator end)
309  {
310  octet_iterator result = start;
311  while (result != end) {
312  utf8::internal::utf_error err_code = utf8::internal::validate_next(result, end);
313  if (err_code != internal::UTF8_OK)
314  return result;
315  }
316  return result;
317  }
318 
319  template <typename octet_iterator>
320  inline bool is_valid(octet_iterator start, octet_iterator end)
321  {
322  return (utf8::find_invalid(start, end) == end);
323  }
324 
325  template <typename octet_iterator>
326  inline bool starts_with_bom (octet_iterator it, octet_iterator end)
327  {
328  return (
329  ((it != end) && (utf8::internal::mask8(*it++)) == bom[0]) &&
330  ((it != end) && (utf8::internal::mask8(*it++)) == bom[1]) &&
331  ((it != end) && (utf8::internal::mask8(*it)) == bom[2])
332  );
333  }
334 } // namespace utf8
335 
336 #endif // header guard
337 
338 
utf8
Definition: checked.h:34