json-writer.c

   1 #include "git-compat-util.h"
   2 #include "json-writer.h"
   3
   4 void jw_init(struct json_writer *jw)
   5 {
   6         struct json_writer blank = JSON_WRITER_INIT;
   7         memcpy(jw, &blank, sizeof(*jw));;
   8 }
   9
  10 void jw_release(struct json_writer *jw)
  11 {
  12         strbuf_release(&jw->json);
  13         strbuf_release(&jw->open_stack);
  14 }
  15
  16 /*
  17  * Append JSON-quoted version of the given string to 'out'.
  18  */
  19 static void append_quoted_string(struct strbuf *out, const char *in)
  20 {
  21         unsigned char c;
  22
  23         strbuf_addch(out, '"');
  24         while ((c = *in++) != '\0') {
  25                 if (c == '"')
  26                         strbuf_addstr(out, "\\\"");
  27                 else if (c == '\\')
  28                         strbuf_addstr(out, "\\\\");
  29                 else if (c == '\n')
  30                         strbuf_addstr(out, "\\n");
  31                 else if (c == '\r')
  32                         strbuf_addstr(out, "\\r");
  33                 else if (c == '\t')
  34                         strbuf_addstr(out, "\\t");
  35                 else if (c == '\f')
  36                         strbuf_addstr(out, "\\f");
  37                 else if (c == '\b')
  38                         strbuf_addstr(out, "\\b");
  39                 else if (c < 0x20)
  40                         strbuf_addf(out, "\\u%04x", c);
  41                 else
  42                         strbuf_addch(out, c);
  43         }
  44         strbuf_addch(out, '"');
  45 }
  46
  47 static void indent_pretty(struct json_writer *jw)
  48 {
  49         int k;
  50
  51         for (k = 0; k < jw->open_stack.len; k++)
  52                 strbuf_addstr(&jw->json, "  ");
  53 }
  54
  55 /*
  56  * Begin an object or array (either top-level or nested within the currently
  57  * open object or array).
  58  */
  59 static void begin(struct json_writer *jw, char ch_open, int pretty)
  60 {
  61         jw->pretty = pretty;
  62
  63         strbuf_addch(&jw->json, ch_open);
  64
  65         strbuf_addch(&jw->open_stack, ch_open);
  66         jw->need_comma = 0;
  67 }
  68
  69 /*
  70  * Assert that the top of the open-stack is an object.
  71  */
  72 static void assert_in_object(const struct json_writer *jw, const char *key)
  73 {
  74         if (!jw->open_stack.len)
  75                 BUG("json-writer: object: missing jw_object_begin(): '%s'", key);
  76         if (jw->open_stack.buf[jw->open_stack.len - 1] != '{')
  77                 BUG("json-writer: object: not in object: '%s'", key);
  78 }
  79
  80 /*
  81  * Assert that the top of the open-stack is an array.
  82  */
  83 static void assert_in_array(const struct json_writer *jw)
  84 {
  85         if (!jw->open_stack.len)
  86                 BUG("json-writer: array: missing jw_array_begin()");
  87         if (jw->open_stack.buf[jw->open_stack.len - 1] != '[')
  88                 BUG("json-writer: array: not in array");
  89 }
  90
  91 /*
  92  * Add comma if we have already seen a member at this level.
  93  */
  94 static void maybe_add_comma(struct json_writer *jw)
  95 {
  96         if (jw->need_comma)
  97                 strbuf_addch(&jw->json, ',');
  98         else
  99                 jw->need_comma = 1;
 100 }
 101
 102 static void fmt_double(struct json_writer *jw, int precision,
 103                               double value)
 104 {
 105         if (precision < 0) {
 106                 strbuf_addf(&jw->json, "%f", value);
 107         } else {
 108                 struct strbuf fmt = STRBUF_INIT;
 109                 strbuf_addf(&fmt, "%%.%df", precision);
 110                 strbuf_addf(&jw->json, fmt.buf, value);
 111                 strbuf_release(&fmt);
 112         }
 113 }
 114
 115 static void object_common(struct json_writer *jw, const char *key)
 116 {
 117         assert_in_object(jw, key);
 118         maybe_add_comma(jw);
 119
 120         if (jw->pretty) {
 121                 strbuf_addch(&jw->json, '\n');
 122                 indent_pretty(jw);
 123         }
 124
 125         append_quoted_string(&jw->json, key);
 126         strbuf_addch(&jw->json, ':');
 127         if (jw->pretty)
 128                 strbuf_addch(&jw->json, ' ');
 129 }
 130
 131 static void array_common(struct json_writer *jw)
 132 {
 133         assert_in_array(jw);
 134         maybe_add_comma(jw);
 135
 136         if (jw->pretty) {
 137                 strbuf_addch(&jw->json, '\n');
 138                 indent_pretty(jw);
 139         }
 140 }
 141
 142 /*
 143  * Assert that the given JSON object or JSON array has been properly
 144  * terminated.  (Has closing bracket.)
 145  */
 146 static void assert_is_terminated(const struct json_writer *jw)
 147 {
 148         if (jw->open_stack.len)
 149                 BUG("json-writer: object: missing jw_end(): '%s'",
 150                     jw->json.buf);
 151 }
 152
 153 void jw_object_begin(struct json_writer *jw, int pretty)
 154 {
 155         begin(jw, '{', pretty);
 156 }
 157
 158 void jw_object_string(struct json_writer *jw, const char *key, const char *value)
 159 {
 160         object_common(jw, key);
 161         append_quoted_string(&jw->json, value);
 162 }
 163
 164 void jw_object_intmax(struct json_writer *jw, const char *key, intmax_t value)
 165 {
 166         object_common(jw, key);
 167         strbuf_addf(&jw->json, "%"PRIdMAX, value);
 168 }
 169
 170 void jw_object_double(struct json_writer *jw, const char *key, int precision,
 171                       double value)
 172 {
 173         object_common(jw, key);
 174         fmt_double(jw, precision, value);
 175 }
 176
 177 void jw_object_true(struct json_writer *jw, const char *key)
 178 {
 179         object_common(jw, key);
 180         strbuf_addstr(&jw->json, "true");
 181 }
 182
 183 void jw_object_false(struct json_writer *jw, const char *key)
 184 {
 185         object_common(jw, key);
 186         strbuf_addstr(&jw->json, "false");
 187 }
 188
 189 void jw_object_bool(struct json_writer *jw, const char *key, int value)
 190 {
 191         if (value)
 192                 jw_object_true(jw, key);
 193         else
 194                 jw_object_false(jw, key);
 195 }
 196
 197 void jw_object_null(struct json_writer *jw, const char *key)
 198 {
 199         object_common(jw, key);
 200         strbuf_addstr(&jw->json, "null");
 201 }
 202
 203 static void increase_indent(struct strbuf *sb,
 204                             const struct json_writer *jw,
 205                             int indent)
 206 {
 207         int k;
 208
 209         strbuf_reset(sb);
 210         for (k = 0; k < jw->json.len; k++) {
 211                 char ch = jw->json.buf[k];
 212                 strbuf_addch(sb, ch);
 213                 if (ch == '\n')
 214                         strbuf_addchars(sb, ' ', indent);
 215         }
 216 }
 217
 218 static void kill_indent(struct strbuf *sb,
 219                         const struct json_writer *jw)
 220 {
 221         int k;
 222         int eat_it = 0;
 223
 224         strbuf_reset(sb);
 225         for (k = 0; k < jw->json.len; k++) {
 226                 char ch = jw->json.buf[k];
 227                 if (eat_it && ch == ' ')
 228                         continue;
 229                 if (ch == '\n') {
 230                         eat_it = 1;
 231                         continue;
 232                 }
 233                 eat_it = 0;
 234                 strbuf_addch(sb, ch);
 235         }
 236 }
 237
 238 static void append_sub_jw(struct json_writer *jw,
 239                           const struct json_writer *value)
 240 {
 241         /*
 242          * If both are pretty, increase the indentation of the sub_jw
 243          * to better fit under the super.
 244          *
 245          * If the super is pretty, but the sub_jw is compact, leave the
 246          * sub_jw compact.  (We don't want to parse and rebuild the sub_jw
 247          * for this debug-ish feature.)
 248          *
 249          * If the super is compact, and the sub_jw is pretty, convert
 250          * the sub_jw to compact.
 251          *
 252          * If both are compact, keep the sub_jw compact.
 253          */
 254         if (jw->pretty && jw->open_stack.len && value->pretty) {
 255                 struct strbuf sb = STRBUF_INIT;
 256                 increase_indent(&sb, value, jw->open_stack.len * 2);
 257                 strbuf_addbuf(&jw->json, &sb);
 258                 strbuf_release(&sb);
 259                 return;
 260         }
 261         if (!jw->pretty && value->pretty) {
 262                 struct strbuf sb = STRBUF_INIT;
 263                 kill_indent(&sb, value);
 264                 strbuf_addbuf(&jw->json, &sb);
 265                 strbuf_release(&sb);
 266                 return;
 267         }
 268
 269         strbuf_addbuf(&jw->json, &value->json);
 270 }
 271
 272 /*
 273  * Append existing (properly terminated) JSON sub-data (object or array)
 274  * as-is onto the given JSON data.
 275  */
 276 void jw_object_sub_jw(struct json_writer *jw, const char *key,
 277                       const struct json_writer *value)
 278 {
 279         assert_is_terminated(value);
 280
 281         object_common(jw, key);
 282         append_sub_jw(jw, value);
 283 }
 284
 285 void jw_object_inline_begin_object(struct json_writer *jw, const char *key)
 286 {
 287         object_common(jw, key);
 288
 289         jw_object_begin(jw, jw->pretty);
 290 }
 291
 292 void jw_object_inline_begin_array(struct json_writer *jw, const char *key)
 293 {
 294         object_common(jw, key);
 295
 296         jw_array_begin(jw, jw->pretty);
 297 }
 298
 299 void jw_array_begin(struct json_writer *jw, int pretty)
 300 {
 301         begin(jw, '[', pretty);
 302 }
 303
 304 void jw_array_string(struct json_writer *jw, const char *value)
 305 {
 306         array_common(jw);
 307         append_quoted_string(&jw->json, value);
 308 }
 309
 310 void jw_array_intmax(struct json_writer *jw, intmax_t value)
 311 {
 312         array_common(jw);
 313         strbuf_addf(&jw->json, "%"PRIdMAX, value);
 314 }
 315
 316 void jw_array_double(struct json_writer *jw, int precision, double value)
 317 {
 318         array_common(jw);
 319         fmt_double(jw, precision, value);
 320 }
 321
 322 void jw_array_true(struct json_writer *jw)
 323 {
 324         array_common(jw);
 325         strbuf_addstr(&jw->json, "true");
 326 }
 327
 328 void jw_array_false(struct json_writer *jw)
 329 {
 330         array_common(jw);
 331         strbuf_addstr(&jw->json, "false");
 332 }
 333
 334 void jw_array_bool(struct json_writer *jw, int value)
 335 {
 336         if (value)
 337                 jw_array_true(jw);
 338         else
 339                 jw_array_false(jw);
 340 }
 341
 342 void jw_array_null(struct json_writer *jw)
 343 {
 344         array_common(jw);
 345         strbuf_addstr(&jw->json, "null");
 346 }
 347
 348 void jw_array_sub_jw(struct json_writer *jw, const struct json_writer *value)
 349 {
 350         assert_is_terminated(value);
 351
 352         array_common(jw);
 353         append_sub_jw(jw, value);
 354 }
 355
 356 void jw_array_argc_argv(struct json_writer *jw, int argc, const char **argv)
 357 {
 358         int k;
 359
 360         for (k = 0; k < argc; k++)
 361                 jw_array_string(jw, argv[k]);
 362 }
 363
 364 void jw_array_argv(struct json_writer *jw, const char **argv)
 365 {
 366         while (*argv)
 367                 jw_array_string(jw, *argv++);
 368 }
 369
 370 void jw_array_inline_begin_object(struct json_writer *jw)
 371 {
 372         array_common(jw);
 373
 374         jw_object_begin(jw, jw->pretty);
 375 }
 376
 377 void jw_array_inline_begin_array(struct json_writer *jw)
 378 {
 379         array_common(jw);
 380
 381         jw_array_begin(jw, jw->pretty);
 382 }
 383
 384 int jw_is_terminated(const struct json_writer *jw)
 385 {
 386         return !jw->open_stack.len;
 387 }
 388
 389 void jw_end(struct json_writer *jw)
 390 {
 391         char ch_open;
 392         int len;
 393
 394         if (!jw->open_stack.len)
 395                 BUG("json-writer: too many jw_end(): '%s'", jw->json.buf);
 396
 397         len = jw->open_stack.len - 1;
 398         ch_open = jw->open_stack.buf[len];
 399
 400         strbuf_setlen(&jw->open_stack, len);
 401         jw->need_comma = 1;
 402
 403         if (jw->pretty) {
 404                 strbuf_addch(&jw->json, '\n');
 405                 indent_pretty(jw);
 406         }
 407
 408         if (ch_open == '{')
 409                 strbuf_addch(&jw->json, '}');
 410         else
 411                 strbuf_addch(&jw->json, ']');
 412 }