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1 /* SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause) */
3 * Simple streaming JSON writer
5 * This takes care of the annoying bits of JSON syntax like the commas
8 * Authors: Stephen Hemminger <stephen@networkplumber.org>
19 #include "json_writer.h"
22 FILE *out
; /* output file */
23 unsigned depth
; /* nesting */
24 bool pretty
; /* optional whitepace */
25 char sep
; /* either nul or comma */
28 /* indentation for pretty print */
29 static void jsonw_indent(json_writer_t
*self
)
32 for (i
= 0; i
< self
->depth
; ++i
)
33 fputs(" ", self
->out
);
36 /* end current line and indent if pretty printing */
37 static void jsonw_eol(json_writer_t
*self
)
42 putc('\n', self
->out
);
46 /* If current object is not empty print a comma */
47 static void jsonw_eor(json_writer_t
*self
)
49 if (self
->sep
!= '\0')
50 putc(self
->sep
, self
->out
);
55 /* Output JSON encoded string */
56 /* Handles C escapes, does not do Unicode */
57 static void jsonw_puts(json_writer_t
*self
, const char *str
)
63 fputs("\\t", self
->out
);
66 fputs("\\n", self
->out
);
69 fputs("\\r", self
->out
);
72 fputs("\\f", self
->out
);
75 fputs("\\b", self
->out
);
78 fputs("\\n", self
->out
);
81 fputs("\\\"", self
->out
);
84 fputs("\\\'", self
->out
);
87 putc(*str
, self
->out
);
92 /* Create a new JSON stream */
93 json_writer_t
*jsonw_new(FILE *f
)
95 json_writer_t
*self
= malloc(sizeof(*self
));
105 /* End output to JSON stream */
106 void jsonw_destroy(json_writer_t
**self_p
)
108 json_writer_t
*self
= *self_p
;
110 assert(self
->depth
== 0);
111 fputs("\n", self
->out
);
117 void jsonw_pretty(json_writer_t
*self
, bool on
)
123 static void jsonw_begin(json_writer_t
*self
, int c
)
131 static void jsonw_end(json_writer_t
*self
, int c
)
133 assert(self
->depth
> 0);
136 if (self
->sep
!= '\0')
143 /* Add a JSON property name */
144 void jsonw_name(json_writer_t
*self
, const char *name
)
149 jsonw_puts(self
, name
);
150 putc(':', self
->out
);
152 putc(' ', self
->out
);
155 void jsonw_printf(json_writer_t
*self
, const char *fmt
, ...)
161 vfprintf(self
->out
, fmt
, ap
);
166 void jsonw_start_object(json_writer_t
*self
)
168 jsonw_begin(self
, '{');
171 void jsonw_end_object(json_writer_t
*self
)
173 jsonw_end(self
, '}');
176 void jsonw_start_array(json_writer_t
*self
)
178 jsonw_begin(self
, '[');
180 putc(' ', self
->out
);
183 void jsonw_end_array(json_writer_t
*self
)
185 if (self
->pretty
&& self
->sep
)
186 putc(' ', self
->out
);
188 jsonw_end(self
, ']');
191 /* JSON value types */
192 void jsonw_string(json_writer_t
*self
, const char *value
)
195 jsonw_puts(self
, value
);
198 void jsonw_bool(json_writer_t
*self
, bool val
)
200 jsonw_printf(self
, "%s", val
? "true" : "false");
203 void jsonw_null(json_writer_t
*self
)
205 jsonw_printf(self
, "null");
208 void jsonw_float_fmt(json_writer_t
*self
, const char *fmt
, double num
)
210 jsonw_printf(self
, fmt
, num
);
213 void jsonw_float(json_writer_t
*self
, double num
)
215 jsonw_printf(self
, "%g", num
);
218 void jsonw_hu(json_writer_t
*self
, unsigned short num
)
220 jsonw_printf(self
, "%hu", num
);
223 void jsonw_uint(json_writer_t
*self
, uint64_t num
)
225 jsonw_printf(self
, "%"PRIu64
, num
);
228 void jsonw_lluint(json_writer_t
*self
, unsigned long long int num
)
230 jsonw_printf(self
, "%llu", num
);
233 void jsonw_int(json_writer_t
*self
, int64_t num
)
235 jsonw_printf(self
, "%"PRId64
, num
);
238 /* Basic name/value objects */
239 void jsonw_string_field(json_writer_t
*self
, const char *prop
, const char *val
)
241 jsonw_name(self
, prop
);
242 jsonw_string(self
, val
);
245 void jsonw_bool_field(json_writer_t
*self
, const char *prop
, bool val
)
247 jsonw_name(self
, prop
);
248 jsonw_bool(self
, val
);
251 void jsonw_float_field(json_writer_t
*self
, const char *prop
, double val
)
253 jsonw_name(self
, prop
);
254 jsonw_float(self
, val
);
257 void jsonw_float_field_fmt(json_writer_t
*self
,
262 jsonw_name(self
, prop
);
263 jsonw_float_fmt(self
, fmt
, val
);
266 void jsonw_uint_field(json_writer_t
*self
, const char *prop
, uint64_t num
)
268 jsonw_name(self
, prop
);
269 jsonw_uint(self
, num
);
272 void jsonw_hu_field(json_writer_t
*self
, const char *prop
, unsigned short num
)
274 jsonw_name(self
, prop
);
278 void jsonw_lluint_field(json_writer_t
*self
,
280 unsigned long long int num
)
282 jsonw_name(self
, prop
);
283 jsonw_lluint(self
, num
);
286 void jsonw_int_field(json_writer_t
*self
, const char *prop
, int64_t num
)
288 jsonw_name(self
, prop
);
289 jsonw_int(self
, num
);
292 void jsonw_null_field(json_writer_t
*self
, const char *prop
)
294 jsonw_name(self
, prop
);
299 int main(int argc
, char **argv
)
301 json_writer_t
*wr
= jsonw_new(stdout
);
303 jsonw_start_object(wr
);
304 jsonw_pretty(wr
, true);
305 jsonw_name(wr
, "Vyatta");
306 jsonw_start_object(wr
);
307 jsonw_string_field(wr
, "url", "http://vyatta.com");
308 jsonw_uint_field(wr
, "downloads", 2000000ul);
309 jsonw_float_field(wr
, "stock", 8.16);
311 jsonw_name(wr
, "ARGV");
312 jsonw_start_array(wr
);
314 jsonw_string(wr
, *++argv
);
317 jsonw_name(wr
, "empty");
318 jsonw_start_array(wr
);
321 jsonw_name(wr
, "NIL");
322 jsonw_start_object(wr
);
323 jsonw_end_object(wr
);
325 jsonw_null_field(wr
, "my_null");
327 jsonw_name(wr
, "special chars");
328 jsonw_start_array(wr
);
329 jsonw_string_field(wr
, "slash", "/");
330 jsonw_string_field(wr
, "newline", "\n");
331 jsonw_string_field(wr
, "tab", "\t");
332 jsonw_string_field(wr
, "ff", "\f");
333 jsonw_string_field(wr
, "quote", "\"");
334 jsonw_string_field(wr
, "tick", "\'");
335 jsonw_string_field(wr
, "backslash", "\\");
338 jsonw_end_object(wr
);
340 jsonw_end_object(wr
);