json-lexer.c

   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     IN_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,
  56     IN_ESCAPE_I,
  57     IN_ESCAPE_I6,
  58     IN_ESCAPE_I64,
  59     IN_WHITESPACE,
  60     IN_START,
  61 };
  62
  63 #define TERMINAL(state) [0 ... 0x7F] = (state)
  64
  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
  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,
  99         ['/'] = IN_DQ_STRING,
 100         ['\\'] = IN_DQ_STRING,
 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,
 108         ['"'] = JSON_STRING,
 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,
 138         ['/'] = IN_DQ_STRING,
 139         ['\\'] = IN_DQ_STRING,
 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,
 147         ['\''] = JSON_STRING,
 148     },
 149
 150     /* Zero */
 151     [IN_ZERO] = {
 152         TERMINAL(JSON_INTEGER),
 153         ['0' ... '9'] = IN_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] = {
 215         ['d'] = JSON_ESCAPE,
 216     },
 217
 218     [IN_ESCAPE_L] = {
 219         ['d'] = JSON_ESCAPE,
 220         ['l'] = IN_ESCAPE_LL,
 221     },
 222
 223     [IN_ESCAPE_I64] = {
 224         ['d'] = JSON_ESCAPE,
 225     },
 226
 227     [IN_ESCAPE_I6] = {
 228         ['4'] = IN_ESCAPE_I64,
 229     },
 230
 231     [IN_ESCAPE_I] = {
 232         ['6'] = IN_ESCAPE_I6,
 233     },
 234
 235     [IN_ESCAPE] = {
 236         ['d'] = JSON_ESCAPE,
 237         ['i'] = JSON_ESCAPE,
 238         ['p'] = JSON_ESCAPE,
 239         ['s'] = JSON_ESCAPE,
 240         ['f'] = JSON_ESCAPE,
 241         ['l'] = IN_ESCAPE_L,
 242         ['I'] = IN_ESCAPE_I,
 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,
 252         ['{'] = JSON_OPERATOR,
 253         ['}'] = JSON_OPERATOR,
 254         ['['] = JSON_OPERATOR,
 255         [']'] = JSON_OPERATOR,
 256         [','] = JSON_OPERATOR,
 257         [':'] = JSON_OPERATOR,
 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();
 272     lexer->x = lexer->y = 0;
 273 }
 274
 275 static int json_lexer_feed_char(JSONLexer *lexer, char ch)
 276 {
 277     int char_consumed, new_state;
 278
 279     lexer->x++;
 280     if (ch == '\n') {
 281         lexer->x = 0;
 282         lexer->y++;
 283     }
 284
 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         }
 291
 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 IN_ERROR:
 306             return -EINVAL;
 307         default:
 308             break;
 309         }
 310         lexer->state = new_state;
 311     } while (!char_consumed);
 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 {
 333     return lexer->state == IN_START ? 0 : json_lexer_feed_char(lexer, 0);
 334 }
 335
 336 void json_lexer_destroy(JSONLexer *lexer)
 337 {
 338     QDECREF(lexer->token);
 339 }