jsmn.c


1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167

#include <stdlib.h>

#include "jsmn.h"

struct jsmn_params {
	jsontok_t *tokens;
	size_t num_tokens;
	int *errpos;
};

/**
 * Read the string from JSON data. Store string 
 */
static int jsmn_parse_string(const unsigned char *js, jsontok_t *token) {
	const unsigned char *p;

	/* Check if string begins from a quote */
	if (js[token->start] != '\"') {
		return -1;
	}

	/* Skip starting quote */
	token->start++;

	for (p = &js[token->start]; *p != '\0'; p++) {
		/* Quote: end of string */
		if (*p == '\"') {
			token->end = p - js;
			return 0;
		}

		/* Backslash: Quoted symbol expected */
		if (*p == '\\') {
			p++;
			switch (*p) {
				/* Allowed escaped symbols */
				case '\"': case '/' : case '\\' : case 'b' :
				case 'f' : case 'r' : case 'n'  : case 't' :
					break;
				/* Allows escaped symbol \uXXXX */
				case 'u':
					/* TODO */
					break;
				/* Unexpected symbol */
				default:
					return -1;
			}
		}
	}
	return -1;
}

static int jsmn_parse_primitive(const unsigned char *js, jsontok_t *token) {
	const unsigned char *p;

	for (p = &js[token->start]; *p != '\0'; p++) {
		switch (*p) {
			case '\t' : case '\r' : case '\n' : case ' ' :
			case ','  : case ']'  : case '}' :
				token->end = p - js;
				return 0;
		}
		if (*p < 32 || *p >= 127) {
			return -1;
		}
	}
	return -1;
}

static void jsmn_error(struct jsmn_params *params, int pos) {
	if (params->errpos != NULL) {
		*params->errpos = pos;
	}
}

static jsontok_t *jsmn_token_start(struct jsmn_params *params, jsontype_t type, int pos) {
	unsigned int i;
	jsontok_t *tokens = params->tokens;
	for (i = 0; i<params->num_tokens; i++) {
		if (tokens[i].start == -1 && tokens[i].end == -1) {
			tokens[i].start = pos;
			tokens[i].type = type;
			return &tokens[i];
		}
	}
	return NULL;
}

static jsontok_t *jsmn_token_end(struct jsmn_params *params, jsontype_t type, int pos) {
	int i;
	jsontok_t *tokens = params->tokens;
	for (i = params->num_tokens - 1; i>= 0; i--) {
		if (tokens[i].type == type && tokens[i].start != -1 && tokens[i].end == -1) {
			tokens[i].end = pos;
			return &tokens[i];
		}
	}
	return NULL;
}

int jsmn_parse(const unsigned char *js, jsontok_t *tokens, size_t num_tokens, int *errpos) {

	struct jsmn_params params;

	int r;
	unsigned int i;
	const unsigned char *p;
	jsontype_t type;
	jsontok_t *cur_token;

	params.num_tokens = num_tokens;
	params.tokens = tokens;
	params.errpos = errpos;

	for (i = 0; i<num_tokens; i++) {
		tokens[i].start = tokens[i].end = -1;
		tokens[i].type = JSON_OTHER;
	}

	for (p = js; *p != '\0'; ) {
		switch (*p) {
			case '{': case '[':
				type = (*p == '{' ? JSON_OBJECT : JSON_ARRAY);
				cur_token = jsmn_token_start(&params, type, p - js);
				cur_token->start = p - js;
				break;
			case '}' : case ']':
				type = (*p == '}' ? JSON_OBJECT : JSON_ARRAY);
				cur_token = jsmn_token_end(&params, type, p - js + 1);
				cur_token->end = p - js + 1;
				break;

			case '-': case '0': case '1' : case '2': case '3' : case '4':
			case '5': case '6': case '7' : case '8': case '9':
			case 't': case 'f': case 'n' :
				cur_token = jsmn_token_start(&params, JSON_OTHER, p - js);
				r = jsmn_parse_primitive(js, cur_token);
				if (r < 0) {
					jsmn_error(&params, p - js);
					return -1;
				}
				p = &js[cur_token->end];
				break;

			case '\"':
				cur_token = jsmn_token_start(&params, JSON_STRING, p - js);
				r = jsmn_parse_string(js, cur_token);
				if (r < 0) {
					jsmn_error(&params, p - js);
					return -1;
				}
				p = &js[cur_token->end];
				break;

			case '\t' : case '\r' : case '\n' : case ':' : case ',': case ' ': 
				break;

			default:
				jsmn_error(&params, p - js);
				return -1;
		}
		p++;
	}
	jsmn_error(&params, 0);
	return 0;
}