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fcc16c22 SH |
1 | /* |
2 | * Simple streaming JSON writer | |
3 | * | |
4 | * This takes care of the annoying bits of JSON syntax like the commas | |
5 | * after elements | |
6 | * | |
7 | * This program is free software; you can redistribute it and/or | |
8 | * modify it under the terms of the GNU General Public License | |
9 | * as published by the Free Software Foundation; either version | |
10 | * 2 of the License, or (at your option) any later version. | |
11 | * | |
12 | * Authors: Stephen Hemminger <stephen@networkplumber.org> | |
13 | */ | |
14 | ||
15 | #include <stdio.h> | |
16 | #include <stdbool.h> | |
17 | #include <stdarg.h> | |
18 | #include <assert.h> | |
19 | #include <malloc.h> | |
20 | #include <inttypes.h> | |
21 | #include <stdint.h> | |
22 | ||
23 | #include "json_writer.h" | |
24 | ||
25 | struct json_writer { | |
26 | FILE *out; /* output file */ | |
27 | unsigned depth; /* nesting */ | |
28 | bool pretty; /* optional whitepace */ | |
29 | char sep; /* either nul or comma */ | |
30 | }; | |
31 | ||
32 | /* indentation for pretty print */ | |
33 | static void jsonw_indent(json_writer_t *self) | |
34 | { | |
35 | unsigned i; | |
36 | for (i = 0; i <= self->depth; ++i) | |
37 | fputs(" ", self->out); | |
38 | } | |
39 | ||
40 | /* end current line and indent if pretty printing */ | |
41 | static void jsonw_eol(json_writer_t *self) | |
42 | { | |
43 | if (!self->pretty) | |
44 | return; | |
45 | ||
46 | putc('\n', self->out); | |
47 | jsonw_indent(self); | |
48 | } | |
49 | ||
50 | /* If current object is not empty print a comma */ | |
51 | static void jsonw_eor(json_writer_t *self) | |
52 | { | |
53 | if (self->sep != '\0') | |
54 | putc(self->sep, self->out); | |
55 | self->sep = ','; | |
56 | } | |
57 | ||
58 | ||
59 | /* Output JSON encoded string */ | |
60 | /* Handles C escapes, does not do Unicode */ | |
61 | static void jsonw_puts(json_writer_t *self, const char *str) | |
62 | { | |
63 | putc('"', self->out); | |
64 | for (; *str; ++str) | |
65 | switch (*str) { | |
66 | case '\t': | |
67 | fputs("\\t", self->out); | |
68 | break; | |
69 | case '\n': | |
70 | fputs("\\n", self->out); | |
71 | break; | |
72 | case '\r': | |
73 | fputs("\\r", self->out); | |
74 | break; | |
75 | case '\f': | |
76 | fputs("\\f", self->out); | |
77 | break; | |
78 | case '\b': | |
79 | fputs("\\b", self->out); | |
80 | break; | |
81 | case '\\': | |
82 | fputs("\\n", self->out); | |
83 | break; | |
84 | case '"': | |
85 | fputs("\\\"", self->out); | |
86 | break; | |
87 | case '\'': | |
88 | fputs("\\\'", self->out); | |
89 | break; | |
90 | default: | |
91 | putc(*str, self->out); | |
92 | } | |
93 | putc('"', self->out); | |
94 | } | |
95 | ||
96 | /* Create a new JSON stream */ | |
97 | json_writer_t *jsonw_new(FILE *f) | |
98 | { | |
99 | json_writer_t *self = malloc(sizeof(*self)); | |
100 | if (self) { | |
101 | self->out = f; | |
102 | self->depth = 0; | |
103 | self->pretty = false; | |
104 | self->sep = '\0'; | |
105 | putc('{', self->out); | |
106 | } | |
107 | return self; | |
108 | } | |
109 | ||
110 | /* End output to JSON stream */ | |
111 | void jsonw_destroy(json_writer_t **self_p) | |
112 | { | |
113 | json_writer_t *self = *self_p; | |
114 | ||
115 | assert(self->depth == 0); | |
116 | jsonw_eol(self); | |
117 | fputs("}\n", self->out); | |
118 | fflush(self->out); | |
119 | free(self); | |
120 | *self_p = NULL; | |
121 | } | |
122 | ||
123 | void jsonw_pretty(json_writer_t *self, bool on) | |
124 | { | |
125 | self->pretty = on; | |
126 | } | |
127 | ||
128 | /* Basic blocks */ | |
129 | static void jsonw_begin(json_writer_t *self, int c) | |
130 | { | |
131 | jsonw_eor(self); | |
132 | putc(c, self->out); | |
133 | ++self->depth; | |
134 | self->sep = '\0'; | |
135 | } | |
136 | ||
137 | static void jsonw_end(json_writer_t *self, int c) | |
138 | { | |
139 | assert(self->depth > 0); | |
140 | ||
141 | --self->depth; | |
142 | if (self->sep != '\0') | |
143 | jsonw_eol(self); | |
144 | putc(c, self->out); | |
145 | self->sep = ','; | |
146 | } | |
147 | ||
148 | ||
149 | /* Add a JSON property name */ | |
150 | void jsonw_name(json_writer_t *self, const char *name) | |
151 | { | |
152 | jsonw_eor(self); | |
153 | jsonw_eol(self); | |
154 | self->sep = '\0'; | |
155 | jsonw_puts(self, name); | |
156 | putc(':', self->out); | |
157 | if (self->pretty) | |
158 | putc(' ', self->out); | |
159 | } | |
160 | ||
161 | static void jsonw_printf(json_writer_t *self, const char *fmt, ...) | |
162 | { | |
163 | va_list ap; | |
164 | ||
165 | va_start(ap, fmt); | |
166 | jsonw_eor(self); | |
167 | vfprintf(self->out, fmt, ap); | |
168 | va_end(ap); | |
169 | } | |
170 | ||
171 | /* Collections */ | |
172 | void jsonw_start_object(json_writer_t *self) | |
173 | { | |
174 | jsonw_begin(self, '{'); | |
175 | } | |
176 | ||
177 | void jsonw_end_object(json_writer_t *self) | |
178 | { | |
179 | jsonw_end(self, '}'); | |
180 | } | |
181 | ||
182 | void jsonw_start_array(json_writer_t *self) | |
183 | { | |
184 | jsonw_begin(self, '['); | |
185 | } | |
186 | ||
187 | void jsonw_end_array(json_writer_t *self) | |
188 | { | |
189 | jsonw_end(self, ']'); | |
190 | } | |
191 | ||
192 | /* JSON value types */ | |
193 | void jsonw_string(json_writer_t *self, const char *value) | |
194 | { | |
195 | jsonw_eor(self); | |
196 | jsonw_puts(self, value); | |
197 | } | |
198 | ||
199 | void jsonw_bool(json_writer_t *self, bool val) | |
200 | { | |
201 | jsonw_printf(self, "%s", val ? "true" : "false"); | |
202 | } | |
203 | ||
204 | #ifdef notused | |
205 | void jsonw_null(json_writer_t *self) | |
206 | { | |
207 | jsonw_printf(self, "null"); | |
208 | } | |
209 | ||
210 | void jsonw_float(json_writer_t *self, double num) | |
211 | { | |
212 | jsonw_printf(self, "%g", num); | |
213 | } | |
214 | #endif | |
215 | ||
216 | void jsonw_uint(json_writer_t *self, uint64_t num) | |
217 | { | |
218 | jsonw_printf(self, "%"PRIu64, num); | |
219 | } | |
220 | ||
221 | void jsonw_int(json_writer_t *self, int64_t num) | |
222 | { | |
223 | jsonw_printf(self, "%"PRId64, num); | |
224 | } | |
225 | ||
226 | /* Basic name/value objects */ | |
227 | void jsonw_string_field(json_writer_t *self, const char *prop, const char *val) | |
228 | { | |
229 | jsonw_name(self, prop); | |
230 | jsonw_string(self, val); | |
231 | } | |
232 | ||
233 | void jsonw_bool_field(json_writer_t *self, const char *prop, bool val) | |
234 | { | |
235 | jsonw_name(self, prop); | |
236 | jsonw_bool(self, val); | |
237 | } | |
238 | ||
239 | #ifdef notused | |
240 | void jsonw_float_field(json_writer_t *self, const char *prop, double val) | |
241 | { | |
242 | jsonw_name(self, prop); | |
243 | jsonw_float(self, val); | |
244 | } | |
245 | #endif | |
246 | ||
247 | void jsonw_uint_field(json_writer_t *self, const char *prop, uint64_t num) | |
248 | { | |
249 | jsonw_name(self, prop); | |
250 | jsonw_uint(self, num); | |
251 | } | |
252 | ||
253 | void jsonw_int_field(json_writer_t *self, const char *prop, int64_t num) | |
254 | { | |
255 | jsonw_name(self, prop); | |
256 | jsonw_int(self, num); | |
257 | } | |
258 | ||
259 | #ifdef notused | |
260 | void jsonw_null_field(json_writer_t *self, const char *prop) | |
261 | { | |
262 | jsonw_name(self, prop); | |
263 | jsonw_null(self); | |
264 | } | |
265 | #endif | |
266 | ||
267 | #ifdef TEST | |
268 | int main(int argc, char **argv) | |
269 | { | |
270 | json_writer_t *wr = jsonw_new(stdout); | |
271 | ||
272 | jsonw_pretty(wr, true); | |
273 | jsonw_name(wr, "Vyatta"); | |
274 | jsonw_start_object(wr); | |
275 | jsonw_string_field(wr, "url", "http://vyatta.com"); | |
276 | jsonw_uint_field(wr, "downloads", 2000000ul); | |
277 | jsonw_float_field(wr, "stock", 8.16); | |
278 | ||
279 | jsonw_name(wr, "ARGV"); | |
280 | jsonw_start_array(wr); | |
281 | while (--argc) | |
282 | jsonw_string(wr, *++argv); | |
283 | jsonw_end_array(wr); | |
284 | ||
285 | jsonw_name(wr, "empty"); | |
286 | jsonw_start_array(wr); | |
287 | jsonw_end_array(wr); | |
288 | ||
289 | jsonw_name(wr, "NIL"); | |
290 | jsonw_start_object(wr); | |
291 | jsonw_end_object(wr); | |
292 | ||
293 | jsonw_null_field(wr, "my_null"); | |
294 | ||
295 | jsonw_name(wr, "special chars"); | |
296 | jsonw_start_array(wr); | |
297 | jsonw_string_field(wr, "slash", "/"); | |
298 | jsonw_string_field(wr, "newline", "\n"); | |
299 | jsonw_string_field(wr, "tab", "\t"); | |
300 | jsonw_string_field(wr, "ff", "\f"); | |
301 | jsonw_string_field(wr, "quote", "\""); | |
302 | jsonw_string_field(wr, "tick", "\'"); | |
303 | jsonw_string_field(wr, "backslash", "\\"); | |
304 | jsonw_end_array(wr); | |
305 | ||
306 | jsonw_end_object(wr); | |
307 | ||
308 | jsonw_destroy(&wr); | |
309 | return 0; | |
310 | } | |
311 | ||
312 | #endif |