src/objson/json_parser.c

   1 /*
   2 Copyright (C) 2005  Georgia Public Library Service
   3 Bill Erickson <highfalutin@gmail.com>
   4
   5 This program is free software; you can redistribute it and/or
   6 modify it under the terms of the GNU General Public License
   7 as published by the Free Software Foundation; either version 2
   8 of the License, or (at your option) any later version.
   9
  10 This program is distributed in the hope that it will be useful,
  11 but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 GNU General Public License for more details.
  14 */
  15
  16
  17 #include "json_parser.h"
  18
  19 /* keep a copy of the length of the current json string so we don't
  20  * have to calculate it in each function
  21  */
  22 int current_strlen; /* XXX need to move this into the function params for thread support */
  23
  24 object* json_parse_string(char* string) {
  25
  26         if(string == NULL) return NULL;
  27
  28         current_strlen = strlen(string);
  29
  30         if(current_strlen == 0)
  31                 return NULL;
  32
  33         object* obj = new_object(NULL);
  34         unsigned long index = 0;
  35
  36         int status = _json_parse_string(string, &index, obj);
  37         if(!status)
  38                 return obj;
  39
  40         if(status == -2)
  41                 return NULL;
  42
  43         return NULL;
  44 }
  45
  46
  47 int _json_parse_string(char* string, unsigned long* index, object* obj) {
  48         assert(string && index && *index < current_strlen);
  49
  50         int status = 0; /* return code from parsing routines */
  51         char* classname = NULL; /* object class hint */
  52         json_eat_ws(string, index, 1); /* remove leading whitespace */
  53
  54         char c = string[*index];
  55
  56         /* remove any leading comments */
  57         if( c == '/' ) {
  58
  59                 while(1) {
  60                         (*index)++; /* move to second comment char */
  61                         status = json_eat_comment(string, index, &classname, 1);
  62                         if(status) return status;
  63
  64                         json_eat_ws(string, index, 1);
  65                         c = string[*index];
  66                         if(c != '/')
  67                                 break;
  68                 }
  69         }
  70
  71         json_eat_ws(string, index, 1); /* remove leading whitespace */
  72
  73         if(*index >= current_strlen)
  74                 return -2;
  75
  76         switch(c) {
  77
  78                 /* json string */
  79                 case '"':
  80                         (*index)++;
  81                         status = json_parse_json_string(string, index, obj);
  82                         break;
  83
  84                 /* json array */
  85                 case '[':
  86                         (*index)++;
  87                         status = json_parse_json_array(string, index, obj);
  88                         break;
  89
  90                 /* json object */
  91                 case '{':
  92                         (*index)++;
  93                         status = json_parse_json_object(string, index, obj);
  94                         break;
  95
  96                 /* NULL */
  97                 case 'n':
  98                 case 'N':
  99                         status = json_parse_json_null(string, index, obj);
 100                         break;
 101
 102
 103                 /* true, false */
 104                 case 'f':
 105                 case 'F':
 106                 case 't':
 107                 case 'T':
 108                         status = json_parse_json_bool(string, index, obj);
 109                         break;
 110
 111                 default:
 112                         if(is_number(c) || c == '.' || c == '-') { /* are we a number? */
 113                                 status = json_parse_json_number(string, index, obj);
 114                                 if(status) return status;
 115                                 break;
 116                         }
 117
 118                         (*index)--;
 119                         /* we should never get here */
 120                         return json_handle_error(string, index, "_json_parse_string() final switch clause");
 121         }
 122
 123         if(status) return status;
 124
 125         json_eat_ws(string, index, 1);
 126
 127         if( *index < current_strlen ) {
 128                 /* remove any trailing comments */
 129                 c = string[*index];
 130                 if( c == '/' ) {
 131                         (*index)++;
 132                         status = json_eat_comment(string, index, NULL, 0);
 133                         if(status) return status;
 134                 }
 135         }
 136
 137         if(classname){
 138                 obj->set_class(obj, classname);
 139                 free(classname);
 140         }
 141
 142         return 0;
 143 }
 144
 145
 146 int json_parse_json_null(char* string, unsigned long* index, object* obj) {
 147
 148         if(*index >= (current_strlen - 3)) {
 149                 return json_handle_error(string, index,
 150                         "_parse_json_string(): invalid null" );
 151         }
 152
 153         if(!strncasecmp(string + (*index), "null", 4)) {
 154                 (*index) += 4;
 155                 obj->is_null = 1;
 156                 return 0;
 157         } else {
 158                 return json_handle_error(string, index,
 159                         "_parse_json_string(): invalid null" );
 160         }
 161 }
 162
 163 /* should be at the first character of the bool at this point */
 164 int json_parse_json_bool(char* string, unsigned long* index, object* obj) {
 165         assert(string && obj && *index < current_strlen);
 166
 167         char* ret = "json_parse_json_bool(): truncated bool";
 168
 169         if( *index >= (current_strlen - 5))
 170                 return json_handle_error(string, index, ret);
 171
 172         if(!strncasecmp( string + (*index), "false", 5)) {
 173                 (*index) += 5;
 174                 obj->bool_value = 0;
 175                 obj->is_bool = 1;
 176                 return 0;
 177         }
 178
 179         if( *index >= (current_strlen - 4))
 180                 return json_handle_error(string, index, ret);
 181
 182         if(!strncasecmp( string + (*index), "true", 4)) {
 183                 (*index) += 4;
 184                 obj->bool_value = 1;
 185                 obj->is_bool = 1;
 186                 return 0;
 187         }
 188
 189         return json_handle_error(string, index, ret);
 190 }
 191
 192
 193 /* expecting the first character of the number */
 194 int json_parse_json_number(char* string, unsigned long* index, object* obj) {
 195         assert(string && obj && *index < current_strlen);
 196
 197         growing_buffer* buf = buffer_init(64);
 198         char c = string[*index];
 199
 200         int done = 0;
 201         int dot_seen = 0;
 202
 203         /* negative number? */
 204         if(c == '-') { buffer_add(buf, "-"); (*index)++; }
 205
 206         while(*index < current_strlen) {
 207
 208                 if(is_number(c))
 209                         buffer_add_char(buf, c);
 210
 211                 else if( c == '.' ) {
 212                         if(dot_seen) {
 213                                 return json_handle_error(string, index,
 214                                         "json_parse_json_number(): malformed json number");
 215                         }
 216                         dot_seen = 1;
 217                         buffer_add_char(buf, c);
 218                 } else {
 219                         done = 1; break;
 220                 }
 221                 (*index)++;
 222                 c = string[*index];
 223                 if(done) break;
 224         }
 225
 226         if(dot_seen) {
 227                 obj->is_double = 1;
 228                 obj->double_value = strtod(buf->buf, NULL);
 229                 buffer_free(buf);
 230                 return 0;
 231
 232         } else {
 233                 obj->is_number = 1;
 234                 obj->num_value = atol(buf->buf);
 235                 buffer_free(buf);
 236                 return 0;
 237         }
 238 }
 239
 240 /* index should point to the character directly following the '['.  when done
 241  * index will point to the character directly following the ']' character
 242  */
 243 int json_parse_json_array(char* string, unsigned long* index, object* obj) {
 244         assert(string && obj && index && *index < current_strlen);
 245
 246         int status;
 247         int in_parse = 0; /* true if this array already contains one item */
 248         obj->is_array = 1;
 249         while(*index < current_strlen) {
 250
 251                 json_eat_ws(string, index, 1);
 252
 253                 if(string[*index] == ']') {
 254                         (*index)++;
 255                         break;
 256                 }
 257
 258                 if(in_parse) {
 259                         json_eat_ws(string, index, 1);
 260                         if(string[*index] != ',') {
 261                                 return json_handle_error(string, index,
 262                                         "json_parse_json_array(): array not followed by a ','");
 263                         }
 264                         (*index)++;
 265                         json_eat_ws(string, index, 1);
 266                 }
 267
 268                 object* item = new_object(NULL);
 269                 status = _json_parse_string(string, index, item);
 270
 271                 if(status) return status;
 272                 obj->push(obj, item);
 273                 in_parse = 1;
 274         }
 275
 276         return 0;
 277 }
 278
 279
 280 /* index should point to the character directly following the '{'.  when done
 281  * index will point to the character directly following the '}'
 282  */
 283 int json_parse_json_object(char* string, unsigned long* index, object* obj) {
 284         assert(string && obj && index && *index < current_strlen);
 285
 286         obj->is_hash = 1;
 287         int status;
 288         int in_parse = 0; /* true if we've already added one item to this object */
 289
 290         while(*index < current_strlen) {
 291
 292                 json_eat_ws(string, index, 1);
 293
 294                 if(string[*index] == '}') {
 295                         (*index)++;
 296                         break;
 297                 }
 298
 299                 if(in_parse) {
 300                         if(string[*index] != ',') {
 301                                 return json_handle_error(string, index,
 302                                         "json_parse_json_object(): object missing ',' betweenn elements" );
 303                         }
 304                         (*index)++;
 305                         json_eat_ws(string, index, 1);
 306                 }
 307
 308                 /* first we grab the hash key */
 309                 object* key_obj = new_object(NULL);
 310                 status = _json_parse_string(string, index, key_obj);
 311                 if(status) return status;
 312
 313                 if(!key_obj->is_string) {
 314                         return json_handle_error(string, index,
 315                                 "_json_parse_json_object(): hash key not a string");
 316                 }
 317
 318                 char* key = key_obj->string_data;
 319
 320                 json_eat_ws(string, index, 1);
 321
 322                 if(string[*index] != ':') {
 323                         return json_handle_error(string, index,
 324                                 "json_parse_json_object(): hash key not followed by ':' character");
 325                 }
 326
 327                 (*index)++;
 328
 329                 /* now grab the value object */
 330                 json_eat_ws(string, index, 1);
 331                 object* value_obj = new_object(NULL);
 332                 status = _json_parse_string(string, index, value_obj);
 333                 if(status) return status;
 334
 335                 /* put the data into the object and continue */
 336                 obj->add_key(obj, key, value_obj);
 337                 free_object(key_obj);
 338                 in_parse = 1;
 339         }
 340         return 0;
 341 }
 342
 343
 344
 345 /* when done, index will point to the character after the closing quote */
 346 int json_parse_json_string(char* string, unsigned long* index, object* obj) {
 347         assert(string && index && *index < current_strlen);
 348
 349         int in_escape = 0;
 350         int done = 0;
 351         growing_buffer* buf = buffer_init(64);
 352
 353         while(*index < current_strlen) {
 354
 355                 char c = string[*index];
 356
 357                 switch(c) {
 358
 359                         case '\\':
 360                                 if(in_escape) {
 361                                         buffer_add(buf, "\\");
 362                                         in_escape = 0;
 363                                 } else
 364                                         in_escape = 1;
 365                                 break;
 366
 367                         case '"':
 368                                 if(in_escape) {
 369                                         buffer_add(buf, "\"");
 370                                         in_escape = 0;
 371                                 } else
 372                                         done = 1;
 373                                 break;
 374
 375                         case 't':
 376                                 if(in_escape) {
 377                                         buffer_add(buf,"\t");
 378                                         in_escape = 0;
 379                                 } else
 380                                         buffer_add_char(buf, c);
 381                                 break;
 382
 383                         case 'b':
 384                                 if(in_escape) {
 385                                         buffer_add(buf,"\b");
 386                                         in_escape = 0;
 387                                 } else
 388                                         buffer_add_char(buf, c);
 389                                 break;
 390
 391                         case 'f':
 392                                 if(in_escape) {
 393                                         buffer_add(buf,"\f");
 394                                         in_escape = 0;
 395                                 } else
 396                                         buffer_add_char(buf, c);
 397                                 break;
 398
 399                         case 'r':
 400                                 if(in_escape) {
 401                                         buffer_add(buf,"\r");
 402                                         in_escape = 0;
 403                                 } else
 404                                         buffer_add_char(buf, c);
 405                                 break;
 406
 407                         case 'n':
 408                                 if(in_escape) {
 409                                         buffer_add(buf,"\n");
 410                                         in_escape = 0;
 411                                 } else
 412                                         buffer_add_char(buf, c);
 413                                 break;
 414
 415                         case 'u':
 416                                 if(in_escape) {
 417                                         (*index)++;
 418
 419                                         if(*index >= (current_strlen - 4)) {
 420                                                 return json_handle_error(string, index,
 421                                                         "json_parse_json_string(): truncated escaped unicode"); }
 422
 423                                         char buff[5];
 424                                         memset(buff,0,5);
 425                                         memcpy(buff, string + (*index), 4);
 426
 427
 428                                         /* ----------------------------------------------------------------------- */
 429                                         /* ----------------------------------------------------------------------- */
 430                                         /* The following chunk was borrowed with permission from
 431                                                 json-c http://oss.metaparadigm.com/json-c/ */
 432                                         unsigned char utf_out[3];
 433                                         memset(utf_out,0,3);
 434
 435                                         #define hexdigit(x) ( ((x) <= '9') ? (x) - '0' : ((x) & 7) + 9)
 436
 437                                         unsigned int ucs_char =
 438                                                 (hexdigit(string[*index] ) << 12) +
 439                                                 (hexdigit(string[*index + 1]) << 8) +
 440                                                 (hexdigit(string[*index + 2]) << 4) +
 441                                                 hexdigit(string[*index + 3]);
 442
 443                                         if (ucs_char < 0x80) {
 444                                                 utf_out[0] = ucs_char;
 445                                                 buffer_add(buf, utf_out);
 446
 447                                         } else if (ucs_char < 0x800) {
 448                                                 utf_out[0] = 0xc0 | (ucs_char >> 6);
 449                                                 utf_out[1] = 0x80 | (ucs_char & 0x3f);
 450                                                 buffer_add(buf, utf_out);
 451
 452                                         } else {
 453                                                 utf_out[0] = 0xe0 | (ucs_char >> 12);
 454                                                 utf_out[1] = 0x80 | ((ucs_char >> 6) & 0x3f);
 455                                                 utf_out[2] = 0x80 | (ucs_char & 0x3f);
 456                                                 buffer_add(buf, utf_out);
 457                                         }
 458                                         /* ----------------------------------------------------------------------- */
 459                                         /* ----------------------------------------------------------------------- */
 460
 461                                         (*index) += 3;
 462                                         in_escape = 0;
 463
 464                                 } else {
 465
 466                                         buffer_add_char(buf, c);
 467                                 }
 468
 469                                 break;
 470
 471                         default:
 472                                 buffer_add_char(buf, c);
 473                 }
 474
 475                 (*index)++;
 476                 if(done) break;
 477         }
 478
 479         obj->set_string(obj, buf->buf);
 480         buffer_free(buf);
 481         return 0;
 482 }
 483
 484
 485 void json_eat_ws(char* string, unsigned long* index, int eat_all) {
 486         assert(string && index);
 487         if(*index >= current_strlen)
 488                 return;
 489
 490         if( eat_all ) { /* removes newlines, etc */
 491                 while(string[*index] == ' '     ||
 492                                 string[*index] == '\n'  ||
 493                                 string[*index] == '\t')
 494                         (*index)++;
 495         }
 496
 497         else
 498                 while(string[*index] == ' ') (*index)++;
 499 }
 500
 501
 502 /* index should be at the '*' character at the beginning of the comment.
 503  * when done, index will point to the first character after the final /
 504  */
 505 int json_eat_comment(char* string, unsigned long* index, char** buffer, int parse_class) {
 506         assert(string && index && *index < current_strlen);
 507
 508         if(string[*index] != '*' && string[*index] != '/' )
 509                 return json_handle_error(string, index,
 510                         "json_eat_comment(): invalid character after /");
 511
 512         /* chop out any // style comments */
 513         if(string[*index] == '/') {
 514                 (*index)++;
 515                 char c = string[*index];
 516                 while(*index < current_strlen) {
 517                         (*index)++;
 518                         if(c == '\n')
 519                                 return 0;
 520                         c = string[*index];
 521                 }
 522                 return 0;
 523         }
 524
 525         (*index)++;
 526
 527         int on_star                     = 0; /* true if we just saw a '*' character */
 528
 529         /* we're just past the '*' */
 530         if(!parse_class) { /* we're not concerned with class hints */
 531                 while(*index < current_strlen) {
 532                         if(string[*index] == '/') {
 533                                 if(on_star) {
 534                                         (*index)++;
 535                                         return 0;
 536                                 }
 537                         }
 538
 539                         if(string[*index] == '*') on_star = 1;
 540                         else on_star = 0;
 541
 542                         (*index)++;
 543                 }
 544                 return 0;
 545         }
 546
 547
 548
 549         growing_buffer* buf = buffer_init(64);
 550
 551         int first_dash          = 0;
 552         int second_dash = 0;
 553         int third_dash          = 0;
 554         int fourth_dash = 0;
 555
 556         int in_hint                     = 0;
 557         int done                                = 0;
 558
 559         /*--S hint--*/   /* <-- Hints  look like this */
 560         /*--E hint--*/
 561
 562         while(*index < current_strlen) {
 563                 char c = string[*index];
 564
 565                 switch(c) {
 566
 567                         case '-':
 568                                 on_star = 0;
 569                                 if(third_dash)                  fourth_dash = 1;
 570                                 else if(in_hint)                third_dash      = 1;
 571                                 else if(first_dash)     second_dash = 1;
 572                                 else                                            first_dash = 1;
 573                                 break;
 574
 575                         case 'S':
 576                                 on_star = 0;
 577                                 if(second_dash && !in_hint) {
 578                                         (*index)++;
 579                                         json_eat_ws(string, index, 1);
 580                                         (*index)--; /* this will get incremented at the bottom of the loop */
 581                                         in_hint = 1;
 582                                         break;
 583                                 }
 584
 585                         case 'E':
 586                                 on_star = 0;
 587                                 if(second_dash && !in_hint) {
 588                                         (*index)++;
 589                                         json_eat_ws(string, index, 1);
 590                                         (*index)--; /* this will get incremented at the bottom of the loop */
 591                                         in_hint = 1;
 592                                         break;
 593                                 }
 594
 595                         case '*':
 596                                 on_star = 1;
 597                                 break;
 598
 599                         case '/':
 600                                 if(on_star)
 601                                         done = 1;
 602                                 else
 603                                 on_star = 0;
 604                                 break;
 605
 606                         default:
 607                                 on_star = 0;
 608                                 if(in_hint)
 609                                         buffer_add_char(buf, c);
 610                 }
 611
 612                 (*index)++;
 613                 if(done) break;
 614         }
 615
 616         if( buf->n_used > 0 && buffer)
 617                 *buffer = buffer_data(buf);
 618
 619         buffer_free(buf);
 620         return 0;
 621 }
 622
 623 int is_number(char c) {
 624         switch(c) {
 625                 case '0':
 626                 case '1':
 627                 case '2':
 628                 case '3':
 629                 case '4':
 630                 case '5':
 631                 case '6':
 632                 case '7':
 633                 case '8':
 634                 case '9':
 635                         return 1;
 636         }
 637         return 0;
 638 }
 639
 640 int json_handle_error(char* string, unsigned long* index, char* err_msg) {
 641
 642         char buf[60];
 643         memset(buf, 0, 60);
 644
 645         if(*index > 30)
 646                 strncpy( buf, string + (*index - 30), 59 );
 647         else
 648                 strncpy( buf, string, 59 );
 649
 650         fprintf(stderr,
 651                         "\nError parsing json string at charracter %c "
 652                         "(code %d) and index %ld\nMsg:\t%s\nNear:\t%s\n\n",
 653                         string[*index], string[*index], *index, err_msg, buf );
 654         return -1;
 655 }
 656
 657