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5ab8558 Add a lexer for JSON
Anthony Liguori authored
1 /*
2 * JSON lexer
3 *
4 * Copyright IBM, Corp. 2009
5 *
6 * Authors:
7 * Anthony Liguori <aliguori@us.ibm.com>
8 *
9 * This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
10 * See the COPYING.LIB file in the top-level directory.
11 *
12 */
13
14 #include "qstring.h"
15 #include "qlist.h"
16 #include "qdict.h"
17 #include "qint.h"
18 #include "qemu-common.h"
19 #include "json-lexer.h"
20
21 /*
22 * \"([^\\\"]|(\\\"\\'\\\\\\/\\b\\f\\n\\r\\t\\u[0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F]))*\"
23 * '([^\\']|(\\\"\\'\\\\\\/\\b\\f\\n\\r\\t\\u[0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F]))*'
24 * 0|([1-9][0-9]*(.[0-9]+)?([eE]([-+])?[0-9]+))
25 * [{}\[\],:]
26 * [a-z]+
27 *
28 */
29
30 enum json_lexer_state {
31 ERROR = 0,
32 IN_DQ_UCODE3,
33 IN_DQ_UCODE2,
34 IN_DQ_UCODE1,
35 IN_DQ_UCODE0,
36 IN_DQ_STRING_ESCAPE,
37 IN_DQ_STRING,
38 IN_SQ_UCODE3,
39 IN_SQ_UCODE2,
40 IN_SQ_UCODE1,
41 IN_SQ_UCODE0,
42 IN_SQ_STRING_ESCAPE,
43 IN_SQ_STRING,
44 IN_ZERO,
45 IN_DIGITS,
46 IN_DIGIT,
47 IN_EXP_E,
48 IN_MANTISSA,
49 IN_MANTISSA_DIGITS,
50 IN_NONZERO_NUMBER,
51 IN_NEG_NONZERO_NUMBER,
52 IN_KEYWORD,
53 IN_ESCAPE,
54 IN_ESCAPE_L,
55 IN_ESCAPE_LL,
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56 IN_ESCAPE_I,
57 IN_ESCAPE_I6,
58 IN_ESCAPE_I64,
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59 IN_WHITESPACE,
60 IN_START,
61 };
62
63 #define TERMINAL(state) [0 ... 0x7F] = (state)
64
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65 /* Return whether TERMINAL is a terminal state and the transition to it
66 from OLD_STATE required lookahead. This happens whenever the table
67 below uses the TERMINAL macro. */
68 #define TERMINAL_NEEDED_LOOKAHEAD(old_state, terminal) \
69 (json_lexer[(old_state)][0] == (terminal))
70
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71 static const uint8_t json_lexer[][256] = {
72 /* double quote string */
73 [IN_DQ_UCODE3] = {
74 ['0' ... '9'] = IN_DQ_STRING,
75 ['a' ... 'f'] = IN_DQ_STRING,
76 ['A' ... 'F'] = IN_DQ_STRING,
77 },
78 [IN_DQ_UCODE2] = {
79 ['0' ... '9'] = IN_DQ_UCODE3,
80 ['a' ... 'f'] = IN_DQ_UCODE3,
81 ['A' ... 'F'] = IN_DQ_UCODE3,
82 },
83 [IN_DQ_UCODE1] = {
84 ['0' ... '9'] = IN_DQ_UCODE2,
85 ['a' ... 'f'] = IN_DQ_UCODE2,
86 ['A' ... 'F'] = IN_DQ_UCODE2,
87 },
88 [IN_DQ_UCODE0] = {
89 ['0' ... '9'] = IN_DQ_UCODE1,
90 ['a' ... 'f'] = IN_DQ_UCODE1,
91 ['A' ... 'F'] = IN_DQ_UCODE1,
92 },
93 [IN_DQ_STRING_ESCAPE] = {
94 ['b'] = IN_DQ_STRING,
95 ['f'] = IN_DQ_STRING,
96 ['n'] = IN_DQ_STRING,
97 ['r'] = IN_DQ_STRING,
98 ['t'] = IN_DQ_STRING,
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99 ['/'] = IN_DQ_STRING,
100 ['\\'] = IN_DQ_STRING,
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101 ['\''] = IN_DQ_STRING,
102 ['\"'] = IN_DQ_STRING,
103 ['u'] = IN_DQ_UCODE0,
104 },
105 [IN_DQ_STRING] = {
106 [1 ... 0xFF] = IN_DQ_STRING,
107 ['\\'] = IN_DQ_STRING_ESCAPE,
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108 ['"'] = JSON_STRING,
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109 },
110
111 /* single quote string */
112 [IN_SQ_UCODE3] = {
113 ['0' ... '9'] = IN_SQ_STRING,
114 ['a' ... 'f'] = IN_SQ_STRING,
115 ['A' ... 'F'] = IN_SQ_STRING,
116 },
117 [IN_SQ_UCODE2] = {
118 ['0' ... '9'] = IN_SQ_UCODE3,
119 ['a' ... 'f'] = IN_SQ_UCODE3,
120 ['A' ... 'F'] = IN_SQ_UCODE3,
121 },
122 [IN_SQ_UCODE1] = {
123 ['0' ... '9'] = IN_SQ_UCODE2,
124 ['a' ... 'f'] = IN_SQ_UCODE2,
125 ['A' ... 'F'] = IN_SQ_UCODE2,
126 },
127 [IN_SQ_UCODE0] = {
128 ['0' ... '9'] = IN_SQ_UCODE1,
129 ['a' ... 'f'] = IN_SQ_UCODE1,
130 ['A' ... 'F'] = IN_SQ_UCODE1,
131 },
132 [IN_SQ_STRING_ESCAPE] = {
133 ['b'] = IN_SQ_STRING,
134 ['f'] = IN_SQ_STRING,
135 ['n'] = IN_SQ_STRING,
136 ['r'] = IN_SQ_STRING,
137 ['t'] = IN_SQ_STRING,
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138 ['/'] = IN_DQ_STRING,
139 ['\\'] = IN_DQ_STRING,
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140 ['\''] = IN_SQ_STRING,
141 ['\"'] = IN_SQ_STRING,
142 ['u'] = IN_SQ_UCODE0,
143 },
144 [IN_SQ_STRING] = {
145 [1 ... 0xFF] = IN_SQ_STRING,
146 ['\\'] = IN_SQ_STRING_ESCAPE,
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147 ['\''] = JSON_STRING,
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148 },
149
150 /* Zero */
151 [IN_ZERO] = {
152 TERMINAL(JSON_INTEGER),
153 ['0' ... '9'] = ERROR,
154 ['.'] = IN_MANTISSA,
155 },
156
157 /* Float */
158 [IN_DIGITS] = {
159 TERMINAL(JSON_FLOAT),
160 ['0' ... '9'] = IN_DIGITS,
161 },
162
163 [IN_DIGIT] = {
164 ['0' ... '9'] = IN_DIGITS,
165 },
166
167 [IN_EXP_E] = {
168 ['-'] = IN_DIGIT,
169 ['+'] = IN_DIGIT,
170 ['0' ... '9'] = IN_DIGITS,
171 },
172
173 [IN_MANTISSA_DIGITS] = {
174 TERMINAL(JSON_FLOAT),
175 ['0' ... '9'] = IN_MANTISSA_DIGITS,
176 ['e'] = IN_EXP_E,
177 ['E'] = IN_EXP_E,
178 },
179
180 [IN_MANTISSA] = {
181 ['0' ... '9'] = IN_MANTISSA_DIGITS,
182 },
183
184 /* Number */
185 [IN_NONZERO_NUMBER] = {
186 TERMINAL(JSON_INTEGER),
187 ['0' ... '9'] = IN_NONZERO_NUMBER,
188 ['e'] = IN_EXP_E,
189 ['E'] = IN_EXP_E,
190 ['.'] = IN_MANTISSA,
191 },
192
193 [IN_NEG_NONZERO_NUMBER] = {
194 ['0'] = IN_ZERO,
195 ['1' ... '9'] = IN_NONZERO_NUMBER,
196 },
197
198 /* keywords */
199 [IN_KEYWORD] = {
200 TERMINAL(JSON_KEYWORD),
201 ['a' ... 'z'] = IN_KEYWORD,
202 },
203
204 /* whitespace */
205 [IN_WHITESPACE] = {
206 TERMINAL(JSON_SKIP),
207 [' '] = IN_WHITESPACE,
208 ['\t'] = IN_WHITESPACE,
209 ['\r'] = IN_WHITESPACE,
210 ['\n'] = IN_WHITESPACE,
211 },
212
213 /* escape */
214 [IN_ESCAPE_LL] = {
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215 ['d'] = JSON_ESCAPE,
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216 },
217
218 [IN_ESCAPE_L] = {
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219 ['d'] = JSON_ESCAPE,
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220 ['l'] = IN_ESCAPE_LL,
221 },
222
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223 [IN_ESCAPE_I64] = {
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224 ['d'] = JSON_ESCAPE,
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225 },
226
227 [IN_ESCAPE_I6] = {
228 ['4'] = IN_ESCAPE_I64,
229 },
230
231 [IN_ESCAPE_I] = {
232 ['6'] = IN_ESCAPE_I6,
233 },
234
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235 [IN_ESCAPE] = {
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236 ['d'] = JSON_ESCAPE,
237 ['i'] = JSON_ESCAPE,
238 ['p'] = JSON_ESCAPE,
239 ['s'] = JSON_ESCAPE,
240 ['f'] = JSON_ESCAPE,
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241 ['l'] = IN_ESCAPE_L,
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242 ['I'] = IN_ESCAPE_I,
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243 },
244
245 /* top level rule */
246 [IN_START] = {
247 ['"'] = IN_DQ_STRING,
248 ['\''] = IN_SQ_STRING,
249 ['0'] = IN_ZERO,
250 ['1' ... '9'] = IN_NONZERO_NUMBER,
251 ['-'] = IN_NEG_NONZERO_NUMBER,
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252 ['{'] = JSON_OPERATOR,
253 ['}'] = JSON_OPERATOR,
254 ['['] = JSON_OPERATOR,
255 [']'] = JSON_OPERATOR,
256 [','] = JSON_OPERATOR,
257 [':'] = JSON_OPERATOR,
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258 ['a' ... 'z'] = IN_KEYWORD,
259 ['%'] = IN_ESCAPE,
260 [' '] = IN_WHITESPACE,
261 ['\t'] = IN_WHITESPACE,
262 ['\r'] = IN_WHITESPACE,
263 ['\n'] = IN_WHITESPACE,
264 },
265 };
266
267 void json_lexer_init(JSONLexer *lexer, JSONLexerEmitter func)
268 {
269 lexer->emit = func;
270 lexer->state = IN_START;
271 lexer->token = qstring_new();
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272 lexer->x = lexer->y = 0;
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273 }
274
275 static int json_lexer_feed_char(JSONLexer *lexer, char ch)
276 {
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277 int char_consumed, new_state;
278
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279 lexer->x++;
280 if (ch == '\n') {
281 lexer->x = 0;
282 lexer->y++;
283 }
284
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285 do {
286 new_state = json_lexer[lexer->state][(uint8_t)ch];
287 char_consumed = !TERMINAL_NEEDED_LOOKAHEAD(lexer->state, new_state);
288 if (char_consumed) {
289 qstring_append_chr(lexer->token, ch);
290 }
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291
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292 switch (new_state) {
293 case JSON_OPERATOR:
294 case JSON_ESCAPE:
295 case JSON_INTEGER:
296 case JSON_FLOAT:
297 case JSON_KEYWORD:
298 case JSON_STRING:
299 lexer->emit(lexer, lexer->token, new_state, lexer->x, lexer->y);
300 case JSON_SKIP:
301 QDECREF(lexer->token);
302 lexer->token = qstring_new();
303 new_state = IN_START;
304 break;
305 case ERROR:
306 return -EINVAL;
307 default:
308 break;
309 }
310 lexer->state = new_state;
311 } while (!char_consumed);
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312 return 0;
313 }
314
315 int json_lexer_feed(JSONLexer *lexer, const char *buffer, size_t size)
316 {
317 size_t i;
318
319 for (i = 0; i < size; i++) {
320 int err;
321
322 err = json_lexer_feed_char(lexer, buffer[i]);
323 if (err < 0) {
324 return err;
325 }
326 }
327
328 return 0;
329 }
330
331 int json_lexer_flush(JSONLexer *lexer)
332 {
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333 return lexer->state == IN_START ? 0 : json_lexer_feed_char(lexer, 0);
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334 }
335
336 void json_lexer_destroy(JSONLexer *lexer)
337 {
338 QDECREF(lexer->token);
339 }
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