2 * Copyright (c) 2009 Petri Lehtinen <petri@digip.org>
4 * Jansson is free software; you can redistribute it and/or modify
5 * it under the terms of the MIT license. See LICENSE for details.
19 #include "jansson_private.h"
20 #include "strbuffer.h"
23 #define TOKEN_INVALID -1
25 #define TOKEN_STRING 256
26 #define TOKEN_INTEGER 257
27 #define TOKEN_REAL 258
28 #define TOKEN_TRUE 259
29 #define TOKEN_FALSE 260
30 #define TOKEN_NULL 261
32 /* read one byte from stream, return EOF on end of file */
33 typedef int (*get_func)(void *data);
35 /* return non-zero if end of file has been reached */
36 typedef int (*eof_func)(void *data);
50 strbuffer_t saved_text;
61 /*** error reporting ***/
63 static void error_init(json_error_t *error)
67 error->text[0] = '\0';
72 static void error_set(json_error_t *error, const lex_t *lex,
76 char text[JSON_ERROR_TEXT_LENGTH];
78 if(!error || error->text[0] != '\0') {
79 /* error already set */
84 vsnprintf(text, JSON_ERROR_TEXT_LENGTH, msg, ap);
89 const char *saved_text = strbuffer_value(&lex->saved_text);
90 error->line = lex->line;
91 if(saved_text && saved_text[0])
93 if(lex->saved_text.length <= 20) {
94 snprintf(error->text, JSON_ERROR_TEXT_LENGTH,
95 "%s near '%s'", text, saved_text);
98 snprintf(error->text, JSON_ERROR_TEXT_LENGTH, "%s", text);
102 snprintf(error->text, JSON_ERROR_TEXT_LENGTH,
103 "%s near end of file", text);
109 snprintf(error->text, JSON_ERROR_TEXT_LENGTH, "%s", text);
114 /*** lexical analyzer ***/
116 void stream_init(stream_t *stream, get_func get, eof_func eof, void *data)
121 stream->stream_pos = 0;
122 stream->buffer[0] = '\0';
123 stream->buffer_pos = 0;
126 static char stream_get(stream_t *stream, json_error_t *error)
130 if(!stream->buffer[stream->buffer_pos])
132 stream->buffer[0] = stream->get(stream->data);
133 stream->buffer_pos = 0;
135 c = stream->buffer[0];
137 if((unsigned char)c >= 0x80 && c != (char)EOF)
139 /* multi-byte UTF-8 sequence */
142 count = utf8_check_first(c);
148 for(i = 1; i < count; i++)
149 stream->buffer[i] = stream->get(stream->data);
151 if(!utf8_check_full(stream->buffer, count))
154 stream->stream_pos += count;
155 stream->buffer[count] = '\0';
158 stream->buffer[1] = '\0';
159 stream->stream_pos++;
163 return stream->buffer[stream->buffer_pos++];
166 error_set(error, NULL, "unable to decode byte 0x%x at position %d",
167 (unsigned char)c, stream->stream_pos);
169 stream->buffer[0] = EOF;
170 stream->buffer[1] = '\0';
171 stream->buffer_pos = 1;
176 static void stream_unget(stream_t *stream, char c)
178 assert(stream->buffer_pos > 0);
179 stream->buffer_pos--;
180 assert(stream->buffer[stream->buffer_pos] == c);
184 static int lex_get(lex_t *lex, json_error_t *error)
186 return stream_get(&lex->stream, error);
189 static int lex_eof(lex_t *lex)
191 return lex->stream.eof(lex->stream.data);
194 static void lex_save(lex_t *lex, char c)
196 strbuffer_append_byte(&lex->saved_text, c);
199 static int lex_get_save(lex_t *lex, json_error_t *error)
201 char c = stream_get(&lex->stream, error);
206 static void lex_unget_unsave(lex_t *lex, char c)
209 stream_unget(&lex->stream, c);
210 d = strbuffer_pop(&lex->saved_text);
214 static void lex_save_cached(lex_t *lex)
216 while(lex->stream.buffer[lex->stream.buffer_pos] != '\0')
218 lex_save(lex, lex->stream.buffer[lex->stream.buffer_pos]);
219 lex->stream.buffer_pos++;
223 /* assumes that str points to 'u' plus at least 4 valid hex digits */
224 static int decode_unicode_escape(const char *str)
229 assert(str[0] == 'u');
231 for(i = 1; i <= 4; i++) {
237 value += c - 'a' + 10;
239 value += c - 'A' + 10;
247 static void lex_scan_string(lex_t *lex, json_error_t *error)
254 lex->value.string = NULL;
255 lex->token = TOKEN_INVALID;
257 c = lex_get_save(lex, error);
261 lex_unget_unsave(lex, c);
263 error_set(error, lex, "premature end of input");
267 else if((unsigned char)c <= 0x1F) {
268 /* control character */
269 lex_unget_unsave(lex, c);
271 error_set(error, lex, "unexpected newline", c);
273 error_set(error, lex, "control character 0x%x", c);
278 c = lex_get_save(lex, error);
280 c = lex_get_save(lex, error);
281 for(i = 0; i < 4; i++) {
283 lex_unget_unsave(lex, c);
284 error_set(error, lex, "invalid escape");
287 c = lex_get_save(lex, error);
290 else if(c == '"' || c == '\\' || c == '/' || c == 'b' ||
291 c == 'f' || c == 'n' || c == 'r' || c == 't')
292 c = lex_get_save(lex, error);
294 lex_unget_unsave(lex, c);
295 error_set(error, lex, "invalid escape");
300 c = lex_get_save(lex, error);
303 /* the actual value is at most of the same length as the source
305 - shortcut escapes (e.g. "\t") (length 2) are converted to 1 byte
306 - a single \uXXXX escape (length 6) is converted to at most 3 bytes
307 - two \uXXXX escapes (length 12) forming an UTF-16 surrogate pair
308 are converted to 4 bytes
310 lex->value.string = malloc(lex->saved_text.length + 1);
311 if(!lex->value.string) {
312 /* this is not very nice, since TOKEN_INVALID is returned */
317 t = lex->value.string;
319 /* + 1 to skip the " */
320 p = strbuffer_value(&lex->saved_text) + 1;
330 value = decode_unicode_escape(p);
333 if(0xD800 <= value && value <= 0xDBFF) {
335 if(*p == '\\' && *(p + 1) == 'u') {
336 int value2 = decode_unicode_escape(++p);
339 if(0xDC00 <= value2 && value2 <= 0xDFFF) {
340 /* valid second surrogate */
342 ((value - 0xD800) << 10) +
347 /* invalid second surrogate */
348 error_set(error, lex,
349 "invalid Unicode '\\u%04X\\u%04X'",
355 /* no second surrogate */
356 error_set(error, lex, "invalid Unicode '\\u%04X'",
361 else if(0xDC00 <= value && value <= 0xDFFF) {
362 error_set(error, lex, "invalid Unicode '\\u%04X'", value);
367 error_set(error, lex, "\\u0000 is not allowed");
371 if(utf8_encode(value, buffer, &length))
374 memcpy(t, buffer, length);
379 case '"': case '\\': case '/':
381 case 'b': *t = '\b'; break;
382 case 'f': *t = '\f'; break;
383 case 'n': *t = '\n'; break;
384 case 'r': *t = '\r'; break;
385 case 't': *t = '\t'; break;
396 lex->token = TOKEN_STRING;
400 free(lex->value.string);
403 static int lex_scan_number(lex_t *lex, char c, json_error_t *error)
405 const char *saved_text;
409 lex->token = TOKEN_INVALID;
412 c = lex_get_save(lex, error);
415 c = lex_get_save(lex, error);
417 lex_unget_unsave(lex, c);
421 else if(isdigit(c)) {
422 c = lex_get_save(lex, error);
424 c = lex_get_save(lex, error);
427 lex_unget_unsave(lex, c);
431 if(c != '.' && c != 'E' && c != 'e') {
434 lex_unget_unsave(lex, c);
436 saved_text = strbuffer_value(&lex->saved_text);
437 value = strtol(saved_text, &end, 10);
438 assert(end == saved_text + lex->saved_text.length);
440 if((value == LONG_MAX && errno == ERANGE) || value > INT_MAX) {
441 error_set(error, lex, "too big integer");
444 else if((value == LONG_MIN && errno == ERANGE) || value < INT_MIN) {
445 error_set(error, lex, "too big negative integer");
449 lex->token = TOKEN_INTEGER;
450 lex->value.integer = (int)value;
455 c = lex_get(lex, error);
460 c = lex_get_save(lex, error);
462 c = lex_get_save(lex, error);
465 if(c == 'E' || c == 'e') {
466 c = lex_get_save(lex, error);
467 if(c == '+' || c == '-')
468 c = lex_get_save(lex, error);
471 lex_unget_unsave(lex, c);
475 c = lex_get_save(lex, error);
477 c = lex_get_save(lex, error);
480 lex_unget_unsave(lex, c);
482 saved_text = strbuffer_value(&lex->saved_text);
483 value = strtod(saved_text, &end);
484 assert(end == saved_text + lex->saved_text.length);
486 if(value == 0 && errno == ERANGE) {
487 error_set(error, lex, "real number underflow");
491 /* Cannot test for +/-HUGE_VAL because the HUGE_VAL constant is
492 only defined in C99 mode. So let's trust in sole errno. */
493 else if(errno == ERANGE) {
494 error_set(error, lex, "real number overflow");
498 lex->token = TOKEN_REAL;
499 lex->value.real = value;
506 static int lex_scan(lex_t *lex, json_error_t *error)
510 strbuffer_clear(&lex->saved_text);
512 if(lex->token == TOKEN_STRING) {
513 free(lex->value.string);
514 lex->value.string = NULL;
517 c = lex_get(lex, error);
518 while(c == ' ' || c == '\t' || c == '\n' || c == '\r')
523 c = lex_get(lex, error);
528 lex->token = TOKEN_EOF;
530 lex->token = TOKEN_INVALID;
536 if(c == '{' || c == '}' || c == '[' || c == ']' || c == ':' || c == ',')
540 lex_scan_string(lex, error);
542 else if(isdigit(c) || c == '-') {
543 if(lex_scan_number(lex, c, error))
547 else if(isupper(c) || islower(c)) {
548 /* eat up the whole identifier for clearer error messages */
549 const char *saved_text;
551 c = lex_get_save(lex, error);
552 while(isupper(c) || islower(c))
553 c = lex_get_save(lex, error);
554 lex_unget_unsave(lex, c);
556 saved_text = strbuffer_value(&lex->saved_text);
558 if(strcmp(saved_text, "true") == 0)
559 lex->token = TOKEN_TRUE;
560 else if(strcmp(saved_text, "false") == 0)
561 lex->token = TOKEN_FALSE;
562 else if(strcmp(saved_text, "null") == 0)
563 lex->token = TOKEN_NULL;
565 lex->token = TOKEN_INVALID;
569 /* save the rest of the input UTF-8 sequence to get an error
570 message of valid UTF-8 */
571 lex_save_cached(lex);
572 lex->token = TOKEN_INVALID;
579 static char *lex_steal_string(lex_t *lex)
582 if(lex->token == TOKEN_STRING)
584 result = lex->value.string;
585 lex->value.string = NULL;
590 static int lex_init(lex_t *lex, get_func get, eof_func eof, void *data)
592 stream_init(&lex->stream, get, eof, data);
593 if(strbuffer_init(&lex->saved_text))
596 lex->token = TOKEN_INVALID;
602 static void lex_close(lex_t *lex)
604 if(lex->token == TOKEN_STRING)
605 free(lex->value.string);
606 strbuffer_close(&lex->saved_text);
612 static json_t *parse_value(lex_t *lex, json_error_t *error);
614 static json_t *parse_object(lex_t *lex, json_error_t *error)
616 json_t *object = json_object();
620 lex_scan(lex, error);
621 if(lex->token == '}')
628 if(lex->token != TOKEN_STRING) {
629 error_set(error, lex, "string or '}' expected");
633 key = lex_steal_string(lex);
637 lex_scan(lex, error);
638 if(lex->token != ':') {
640 error_set(error, lex, "':' expected");
644 lex_scan(lex, error);
645 value = parse_value(lex, error);
651 if(json_object_set_nocheck(object, key, value)) {
660 lex_scan(lex, error);
661 if(lex->token != ',')
664 lex_scan(lex, error);
667 if(lex->token != '}') {
668 error_set(error, lex, "'}' expected");
679 static json_t *parse_array(lex_t *lex, json_error_t *error)
681 json_t *array = json_array();
685 lex_scan(lex, error);
686 if(lex->token == ']')
690 json_t *elem = parse_value(lex, error);
694 if(json_array_append(array, elem)) {
700 lex_scan(lex, error);
701 if(lex->token != ',')
704 lex_scan(lex, error);
707 if(lex->token != ']') {
708 error_set(error, lex, "']' expected");
719 static json_t *parse_value(lex_t *lex, json_error_t *error)
725 json = json_string_nocheck(lex->value.string);
729 case TOKEN_INTEGER: {
730 json = json_integer(lex->value.integer);
735 json = json_real(lex->value.real);
752 json = parse_object(lex, error);
756 json = parse_array(lex, error);
760 error_set(error, lex, "invalid token");
764 error_set(error, lex, "unexpected token");
774 json_t *parse_json(lex_t *lex, json_error_t *error)
778 lex_scan(lex, error);
779 if(lex->token != '[' && lex->token != '{') {
780 error_set(error, lex, "'[' or '{' expected");
784 return parse_value(lex, error);
793 static int string_get(void *data)
796 string_data_t *stream = (string_data_t *)data;
797 c = stream->data[stream->pos];
807 static int string_eof(void *data)
809 string_data_t *stream = (string_data_t *)data;
810 return (stream->data[stream->pos] == '\0');
813 json_t *json_loads(const char *string, json_error_t *error)
818 string_data_t stream_data = {
823 if(lex_init(&lex, string_get, string_eof, (void *)&stream_data))
826 result = parse_json(&lex, error);
830 lex_scan(&lex, error);
831 if(lex.token != TOKEN_EOF) {
832 error_set(error, &lex, "end of file expected");
842 json_t *json_loadf(FILE *input, json_error_t *error)
847 if(lex_init(&lex, (get_func)fgetc, (eof_func)feof, input))
850 result = parse_json(&lex, error);
854 lex_scan(&lex, error);
855 if(lex.token != TOKEN_EOF) {
856 error_set(error, &lex, "end of file expected");
866 json_t *json_load_file(const char *path, json_error_t *error)
873 fp = fopen(path, "r");
876 error_set(error, NULL, "unable to open %s: %s",
877 path, strerror(errno));
881 result = json_loadf(fp, error);