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core.h
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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
31 #ifndef UTF8_FOR_CPP_CORE_H_2675DCD0_9480_4c0c_B92A_CC14C027B731
32 #define UTF8_FOR_CPP_CORE_H_2675DCD0_9480_4c0c_B92A_CC14C027B731
33
34 #include <boost/cstdint.hpp>
35
36 #include <iterator>
37
38 namespace utf8
39 {
40 // The typedefs for 8-bit, 16-bit and 32-bit unsigned integers
41 // You may need to change them to match your system.
42 // These typedefs have the same names as ones from cstdint, or boost/cstdint
43 typedef boost::uint8_t uint8_t;
44 typedef boost::uint16_t uint16_t;
45 typedef boost::uint32_t uint32_t;
46
47 // Helper code - not intended to be directly called by the library users. May be changed at any time
48 namespace internal
49 {
50 // Unicode constants
51 // Leading (high) surrogates: 0xd800 - 0xdbff
52 // Trailing (low) surrogates: 0xdc00 - 0xdfff
53 const uint16_t LEAD_SURROGATE_MIN = 0xd800u;
54 const uint16_t LEAD_SURROGATE_MAX = 0xdbffu;
55 const uint16_t TRAIL_SURROGATE_MIN = 0xdc00u;
56 const uint16_t TRAIL_SURROGATE_MAX = 0xdfffu;
57 const uint16_t LEAD_OFFSET = LEAD_SURROGATE_MIN - (0x10000 >> 10);
58 const uint32_t SURROGATE_OFFSET = 0x10000u - (LEAD_SURROGATE_MIN << 10) - TRAIL_SURROGATE_MIN;
59
60 // Maximum valid value for a Unicode code point
61 const uint32_t CODE_POINT_MAX = 0x0010ffffu;
62
63 template<typename octet_type>
64 inline uint8_t mask8(octet_type oc)
65 {
66 return static_cast<uint8_t>(0xff & oc);
67 }
68 template<typename u16_type>
69 inline uint16_t mask16(u16_type oc)
70 {
71 return static_cast<uint16_t>(0xffff & oc);
72 }
73 template<typename octet_type>
74 inline bool is_trail(octet_type oc)
75 {
76 return ((mask8(oc) >> 6) == 0x2);
77 }
78
79 template <typename u16>
80 inline bool is_surrogate(u16 cp)
81 {
82 return (cp >= LEAD_SURROGATE_MIN && cp <= TRAIL_SURROGATE_MAX);
83 }
84
85 template <typename u32>
86 inline bool is_code_point_valid(u32 cp)
87 {
88 return (cp <= CODE_POINT_MAX && !is_surrogate(cp) && cp != 0xfffe && cp != 0xffff);
89 }
90
91 template <typename octet_iterator>
92 inline typename std::iterator_traits<octet_iterator>::difference_type
93 sequence_length(octet_iterator lead_it)
94 {
95 uint8_t lead = mask8(*lead_it);
96 if (lead < 0x80)
97 return 1;
98 else if ((lead >> 5) == 0x6)
99 return 2;
100 else if ((lead >> 4) == 0xe)
101 return 3;
102 else if ((lead >> 3) == 0x1e)
103 return 4;
104 else
105 return 0;
106 }
107
108 enum utf_error {OK, NOT_ENOUGH_ROOM, INVALID_LEAD, INCOMPLETE_SEQUENCE, OVERLONG_SEQUENCE, INVALID_CODE_POINT};
109
110 template <typename octet_iterator>
111 utf_error validate_next(octet_iterator& it, octet_iterator end, uint32_t* code_point)
112 {
113 uint32_t cp = mask8(*it);
114 // Check the lead octet
115 typedef typename std::iterator_traits<octet_iterator>::difference_type octet_difference_type;
116 octet_difference_type length = sequence_length(it);
117
118 // "Shortcut" for ASCII characters
119 if (length == 1) {
120 if (end - it > 0) {
121 if (code_point)
122 *code_point = cp;
123 ++it;
124 return OK;
125 }
126 else
127 return NOT_ENOUGH_ROOM;
128 }
129
130 // Do we have enough memory?
131 if (std::distance(it, end) < length)
132 return NOT_ENOUGH_ROOM;
133
134 // Check trail octets and calculate the code point
135 switch (length) {
136 case 0:
137 return INVALID_LEAD;
138 break;
139 case 2:
140 if (is_trail(*(++it))) {
141 cp = ((cp << 6) & 0x7ff) + ((*it) & 0x3f);
142 }
143 else {
144 --it;
145 return INCOMPLETE_SEQUENCE;
146 }
147 break;
148 case 3:
149 if (is_trail(*(++it))) {
150 cp = ((cp << 12) & 0xffff) + ((mask8(*it) << 6) & 0xfff);
151 if (is_trail(*(++it))) {
152 cp += (*it) & 0x3f;
153 }
154 else {
155 std::advance(it, -2);
156 return INCOMPLETE_SEQUENCE;
157 }
158 }
159 else {
160 --it;
161 return INCOMPLETE_SEQUENCE;
162 }
163 break;
164 case 4:
165 if (is_trail(*(++it))) {
166 cp = ((cp << 18) & 0x1fffff) + ((mask8(*it) << 12) & 0x3ffff);
167 if (is_trail(*(++it))) {
168 cp += (mask8(*it) << 6) & 0xfff;
169 if (is_trail(*(++it))) {
170 cp += (*it) & 0x3f;
171 }
172 else {
173 std::advance(it, -3);
174 return INCOMPLETE_SEQUENCE;
175 }
176 }
177 else {
178 std::advance(it, -2);
179 return INCOMPLETE_SEQUENCE;
180 }
181 }
182 else {
183 --it;
184 return INCOMPLETE_SEQUENCE;
185 }
186 break;
187 }
188 // Is the code point valid?
189 if (!is_code_point_valid(cp)) {
190 for (octet_difference_type i = 0; i < length - 1; ++i)
191 --it;
192 return INVALID_CODE_POINT;
193 }
194
195 if (code_point)
196 *code_point = cp;
197
198 if (cp < 0x80) {
199 if (length != 1) {
200 std::advance(it, -(length-1));
201 return OVERLONG_SEQUENCE;
202 }
203 }
204 else if (cp < 0x800) {
205 if (length != 2) {
206 std::advance(it, -(length-1));
207 return OVERLONG_SEQUENCE;
208 }
209 }
210 else if (cp < 0x10000) {
211 if (length != 3) {
212 std::advance(it, -(length-1));
213 return OVERLONG_SEQUENCE;
214 }
215 }
216
217 ++it;
218 return OK;
219 }
220
221 template <typename octet_iterator>
222 inline utf_error validate_next(octet_iterator& it, octet_iterator end) {
223 return validate_next(it, end, 0);
224 }
225
226 } // namespace internal
227
229
230 // Byte order mark
231 const uint8_t bom[] = {0xef, 0xbb, 0xbf};
232
233 template <typename octet_iterator>
234 octet_iterator find_invalid(octet_iterator start, octet_iterator end)
235 {
236 octet_iterator result = start;
237 while (result != end) {
238 internal::utf_error err_code = internal::validate_next(result, end);
239 if (err_code != internal::OK)
240 return result;
241 }
242 return result;
243 }
244
245 template <typename octet_iterator>
246 inline bool is_valid(octet_iterator start, octet_iterator end)
247 {
248 return (find_invalid(start, end) == end);
249 }
250
251 template <typename octet_iterator>
252 inline bool is_bom (octet_iterator it)
253 {
254 return (
255 (internal::mask8(*it++)) == bom[0] &&
256 (internal::mask8(*it++)) == bom[1] &&
257 (internal::mask8(*it)) == bom[2]
258 );
259 }
260 } // namespace utf8
261
262 #endif // header guard
263
264