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 namespace utf8
34 {
35  // The typedefs for 8-bit, 16-bit and 32-bit unsigned integers
36  // You may need to change them to match your system.
37  // These typedefs have the same names as ones from cstdint, or boost/cstdint
38  typedef unsigned char uint8_t;
39  typedef unsigned short uint16_t;
40  typedef unsigned int uint32_t;
41 
42 // Helper code - not intended to be directly called by the library users. May be changed at any time
43 namespace internal
44 {
45  // Unicode constants
46  // Leading (high) surrogates: 0xd800 - 0xdbff
47  // Trailing (low) surrogates: 0xdc00 - 0xdfff
48  const uint16_t LEAD_SURROGATE_MIN = 0xd800u;
49  const uint16_t LEAD_SURROGATE_MAX = 0xdbffu;
50  const uint16_t TRAIL_SURROGATE_MIN = 0xdc00u;
51  const uint16_t TRAIL_SURROGATE_MAX = 0xdfffu;
52  const uint16_t LEAD_OFFSET = LEAD_SURROGATE_MIN - (0x10000 >> 10);
53  const uint32_t SURROGATE_OFFSET = 0x10000u - (LEAD_SURROGATE_MIN << 10) - TRAIL_SURROGATE_MIN;
54 
55  // Maximum valid value for a Unicode code point
56  const uint32_t CODE_POINT_MAX = 0x0010ffffu;
57 
58  template<typename octet_type>
59  inline uint8_t mask8(octet_type oc)
60  {
61  return static_cast<uint8_t>(0xff & oc);
62  }
63  template<typename u16_type>
64  inline uint16_t mask16(u16_type oc)
65  {
66  return static_cast<uint16_t>(0xffff & oc);
67  }
68  template<typename octet_type>
69  inline bool is_trail(octet_type oc)
70  {
71  return ((utf8::internal::mask8(oc) >> 6) == 0x2);
72  }
73 
74  template <typename u16>
75  inline bool is_lead_surrogate(u16 cp)
76  {
77  return (cp >= LEAD_SURROGATE_MIN && cp <= LEAD_SURROGATE_MAX);
78  }
79 
80  template <typename u16>
81  inline bool is_trail_surrogate(u16 cp)
82  {
83  return (cp >= TRAIL_SURROGATE_MIN && cp <= TRAIL_SURROGATE_MAX);
84  }
85 
86  template <typename u16>
87  inline bool is_surrogate(u16 cp)
88  {
89  return (cp >= LEAD_SURROGATE_MIN && cp <= TRAIL_SURROGATE_MAX);
90  }
91 
92  template <typename u32>
93  inline bool is_code_point_valid(u32 cp)
94  {
95  return (cp <= CODE_POINT_MAX && !utf8::internal::is_surrogate(cp));
96  }
97 
98  template <typename octet_iterator>
99  inline typename std::iterator_traits<octet_iterator>::difference_type
100  sequence_length(octet_iterator lead_it)
101  {
102  uint8_t lead = utf8::internal::mask8(*lead_it);
103  if (lead < 0x80)
104  return 1;
105  else if ((lead >> 5) == 0x6)
106  return 2;
107  else if ((lead >> 4) == 0xe)
108  return 3;
109  else if ((lead >> 3) == 0x1e)
110  return 4;
111  else
112  return 0;
113  }
114 
115  template <typename octet_difference_type>
116  inline bool is_overlong_sequence(uint32_t cp, octet_difference_type length)
117  {
118  if (cp < 0x80) {
119  if (length != 1)
120  return true;
121  }
122  else if (cp < 0x800) {
123  if (length != 2)
124  return true;
125  }
126  else if (cp < 0x10000) {
127  if (length != 3)
128  return true;
129  }
130 
131  return false;
132  }
133 
134  enum utf_error {UTF8_OK, NOT_ENOUGH_ROOM, INVALID_LEAD, INCOMPLETE_SEQUENCE, OVERLONG_SEQUENCE, INVALID_CODE_POINT};
135 
137  template <typename octet_iterator>
138  utf_error increase_safely(octet_iterator& it, octet_iterator end)
139  {
140  if (++it == end)
141  return NOT_ENOUGH_ROOM;
142 
143  if (!utf8::internal::is_trail(*it))
144  return INCOMPLETE_SEQUENCE;
145 
146  return UTF8_OK;
147  }
148 
149  #define UTF8_CPP_INCREASE_AND_RETURN_ON_ERROR(IT, END) {utf_error ret = increase_safely(IT, END); if (ret != UTF8_OK) return ret;}
150 
152  template <typename octet_iterator>
153  utf_error get_sequence_1(octet_iterator& it, octet_iterator end, uint32_t& code_point)
154  {
155  if (it == end)
156  return NOT_ENOUGH_ROOM;
157 
158  code_point = utf8::internal::mask8(*it);
159 
160  return UTF8_OK;
161  }
162 
163  template <typename octet_iterator>
164  utf_error get_sequence_2(octet_iterator& it, octet_iterator end, uint32_t& code_point)
165  {
166  if (it == end)
167  return NOT_ENOUGH_ROOM;
168 
169  code_point = utf8::internal::mask8(*it);
170 
171  UTF8_CPP_INCREASE_AND_RETURN_ON_ERROR(it, end)
172 
173  code_point = ((code_point << 6) & 0x7ff) + ((*it) & 0x3f);
174 
175  return UTF8_OK;
176  }
177 
178  template <typename octet_iterator>
179  utf_error get_sequence_3(octet_iterator& it, octet_iterator end, uint32_t& code_point)
180  {
181  if (it == end)
182  return NOT_ENOUGH_ROOM;
183 
184  code_point = utf8::internal::mask8(*it);
185 
186  UTF8_CPP_INCREASE_AND_RETURN_ON_ERROR(it, end)
187 
188  code_point = ((code_point << 12) & 0xffff) + ((utf8::internal::mask8(*it) << 6) & 0xfff);
189 
190  UTF8_CPP_INCREASE_AND_RETURN_ON_ERROR(it, end)
191 
192  code_point += (*it) & 0x3f;
193 
194  return UTF8_OK;
195  }
196 
197  template <typename octet_iterator>
198  utf_error get_sequence_4(octet_iterator& it, octet_iterator end, uint32_t& code_point)
199  {
200  if (it == end)
201  return NOT_ENOUGH_ROOM;
202 
203  code_point = utf8::internal::mask8(*it);
204 
205  UTF8_CPP_INCREASE_AND_RETURN_ON_ERROR(it, end)
206 
207  code_point = ((code_point << 18) & 0x1fffff) + ((utf8::internal::mask8(*it) << 12) & 0x3ffff);
208 
209  UTF8_CPP_INCREASE_AND_RETURN_ON_ERROR(it, end)
210 
211  code_point += (utf8::internal::mask8(*it) << 6) & 0xfff;
212 
213  UTF8_CPP_INCREASE_AND_RETURN_ON_ERROR(it, end)
214 
215  code_point += (*it) & 0x3f;
216 
217  return UTF8_OK;
218  }
219 
220  #undef UTF8_CPP_INCREASE_AND_RETURN_ON_ERROR
221 
222  template <typename octet_iterator>
223  utf_error validate_next(octet_iterator& it, octet_iterator end, uint32_t& code_point)
224  {
225  // Save the original value of it so we can go back in case of failure
226  // Of course, it does not make much sense with i.e. stream iterators
227  octet_iterator original_it = it;
228 
229  uint32_t cp = 0;
230  // Determine the sequence length based on the lead octet
231  typedef typename std::iterator_traits<octet_iterator>::difference_type octet_difference_type;
232  const octet_difference_type length = utf8::internal::sequence_length(it);
233 
234  // Get trail octets and calculate the code point
235  utf_error err = UTF8_OK;
236  switch (length) {
237  case 0:
238  return INVALID_LEAD;
239  case 1:
240  err = utf8::internal::get_sequence_1(it, end, cp);
241  break;
242  case 2:
243  err = utf8::internal::get_sequence_2(it, end, cp);
244  break;
245  case 3:
246  err = utf8::internal::get_sequence_3(it, end, cp);
247  break;
248  case 4:
249  err = utf8::internal::get_sequence_4(it, end, cp);
250  break;
251  }
252 
253  if (err == UTF8_OK) {
254  // Decoding succeeded. Now, security checks...
255  if (utf8::internal::is_code_point_valid(cp)) {
256  if (!utf8::internal::is_overlong_sequence(cp, length)){
257  // Passed! Return here.
258  code_point = cp;
259  ++it;
260  return UTF8_OK;
261  }
262  else
263  err = OVERLONG_SEQUENCE;
264  }
265  else
266  err = INVALID_CODE_POINT;
267  }
268 
269  // Failure branch - restore the original value of the iterator
270  it = original_it;
271  return err;
272  }
273 
274  template <typename octet_iterator>
275  inline utf_error validate_next(octet_iterator& it, octet_iterator end) {
276  uint32_t ignored;
277  return utf8::internal::validate_next(it, end, ignored);
278  }
279 
280 } // namespace internal
281 
283 
284  // Byte order mark
285  const uint8_t bom[] = {0xef, 0xbb, 0xbf};
286 
287  template <typename octet_iterator>
288  octet_iterator find_invalid(octet_iterator start, octet_iterator end)
289  {
290  octet_iterator result = start;
291  while (result != end) {
292  utf8::internal::utf_error err_code = utf8::internal::validate_next(result, end);
293  if (err_code != internal::UTF8_OK)
294  return result;
295  }
296  return result;
297  }
298 
299  template <typename octet_iterator>
300  inline bool is_valid(octet_iterator start, octet_iterator end)
301  {
302  return (utf8::find_invalid(start, end) == end);
303  }
304 
305  template <typename octet_iterator>
306  inline bool starts_with_bom (octet_iterator it, octet_iterator end)
307  {
308  return (
309  ((it != end) && (utf8::internal::mask8(*it++)) == bom[0]) &&
310  ((it != end) && (utf8::internal::mask8(*it++)) == bom[1]) &&
311  ((it != end) && (utf8::internal::mask8(*it)) == bom[2])
312  );
313  }
314 
315  //Deprecated in release 2.3
316  template <typename octet_iterator>
317  inline bool is_bom (octet_iterator it)
318  {
319  return (
320  (utf8::internal::mask8(*it++)) == bom[0] &&
321  (utf8::internal::mask8(*it++)) == bom[1] &&
322  (utf8::internal::mask8(*it)) == bom[2]
323  );
324  }
325 } // namespace utf8
326 
327 #endif // header guard
328 
329 
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