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json_object.h 28 kB

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  1. /*
  2. * $Id: json_object.h,v 1.12 2006/01/30 23:07:57 mclark Exp $
  3. *
  4. * Copyright (c) 2004, 2005 Metaparadigm Pte. Ltd.
  5. * Michael Clark <michael@metaparadigm.com>
  6. * Copyright (c) 2009 Hewlett-Packard Development Company, L.P.
  7. *
  8. * This library is free software; you can redistribute it and/or modify
  9. * it under the terms of the MIT license. See COPYING for details.
  10. *
  11. */
  12. #ifndef _json_object_h_
  13. #define _json_object_h_
  14. #ifdef __GNUC__
  15. #define THIS_FUNCTION_IS_DEPRECATED(func) func __attribute__ ((deprecated))
  16. #elif defined(_MSC_VER)
  17. #define THIS_FUNCTION_IS_DEPRECATED(func) __declspec(deprecated) func
  18. #else
  19. #define THIS_FUNCTION_IS_DEPRECATED(func) func
  20. #endif
  21. #include "json_inttypes.h"
  22. #ifdef __cplusplus
  23. extern "C" {
  24. #endif
  25. #define JSON_OBJECT_DEF_HASH_ENTRIES 16
  26. /**
  27. * A flag for the json_object_to_json_string_ext() and
  28. * json_object_to_file_ext() functions which causes the output
  29. * to have no extra whitespace or formatting applied.
  30. */
  31. #define JSON_C_TO_STRING_PLAIN 0
  32. /**
  33. * A flag for the json_object_to_json_string_ext() and
  34. * json_object_to_file_ext() functions which causes the output to have
  35. * minimal whitespace inserted to make things slightly more readable.
  36. */
  37. #define JSON_C_TO_STRING_SPACED (1<<0)
  38. /**
  39. * A flag for the json_object_to_json_string_ext() and
  40. * json_object_to_file_ext() functions which causes
  41. * the output to be formatted.
  42. *
  43. * See the "Two Space Tab" option at http://jsonformatter.curiousconcept.com/
  44. * for an example of the format.
  45. */
  46. #define JSON_C_TO_STRING_PRETTY (1<<1)
  47. /**
  48. * A flag for the json_object_to_json_string_ext() and
  49. * json_object_to_file_ext() functions which causes
  50. * the output to be formatted.
  51. *
  52. * Instead of a "Two Space Tab" this gives a single tab character.
  53. */
  54. #define JSON_C_TO_STRING_PRETTY_TAB (1<<3)
  55. /**
  56. * A flag to drop trailing zero for float values
  57. */
  58. #define JSON_C_TO_STRING_NOZERO (1<<2)
  59. /**
  60. * Don't escape forward slashes.
  61. */
  62. #define JSON_C_TO_STRING_NOSLASHESCAPE (1<<4)
  63. /**
  64. * A flag for the json_object_object_add_ex function which
  65. * causes the value to be added without a check if it already exists.
  66. * Note: it is the responsibilty of the caller to ensure that no
  67. * key is added multiple times. If this is done, results are
  68. * unpredictable. While this option is somewhat dangerous, it
  69. * permits potentially large performance savings in code that
  70. * knows for sure the key values are unique (e.g. because the
  71. * code adds a well-known set of constant key values).
  72. */
  73. #define JSON_C_OBJECT_ADD_KEY_IS_NEW (1<<1)
  74. /**
  75. * A flag for the json_object_object_add_ex function which
  76. * flags the key as being constant memory. This means that
  77. * the key will NOT be copied via strdup(), resulting in a
  78. * potentially huge performance win (malloc, strdup and
  79. * free are usually performance hogs). It is acceptable to
  80. * use this flag for keys in non-constant memory blocks if
  81. * the caller ensure that the memory holding the key lives
  82. * longer than the corresponding json object. However, this
  83. * is somewhat dangerous and should only be done if really
  84. * justified.
  85. * The general use-case for this flag is cases where the
  86. * key is given as a real constant value in the function
  87. * call, e.g. as in
  88. * json_object_object_add_ex(obj, "ip", json,
  89. * JSON_C_OBJECT_KEY_IS_CONSTANT);
  90. */
  91. #define JSON_C_OBJECT_KEY_IS_CONSTANT (1<<2)
  92. #undef FALSE
  93. #define FALSE ((json_bool)0)
  94. #undef TRUE
  95. #define TRUE ((json_bool)1)
  96. extern const char *json_number_chars;
  97. extern const char *json_hex_chars;
  98. /* CAW: added for ANSI C iteration correctness */
  99. struct json_object_iter
  100. {
  101. char *key;
  102. struct json_object *val;
  103. struct lh_entry *entry;
  104. };
  105. /* forward structure definitions */
  106. typedef int json_bool;
  107. typedef struct printbuf printbuf;
  108. typedef struct lh_table lh_table;
  109. typedef struct array_list array_list;
  110. typedef struct json_object json_object;
  111. typedef struct json_object_iter json_object_iter;
  112. typedef struct json_tokener json_tokener;
  113. /**
  114. * Type of custom user delete functions. See json_object_set_serializer.
  115. */
  116. typedef void (json_object_delete_fn)(struct json_object *jso, void *userdata);
  117. /**
  118. * Type of a custom serialization function. See json_object_set_serializer.
  119. */
  120. typedef int (json_object_to_json_string_fn)(struct json_object *jso,
  121. struct printbuf *pb,
  122. int level,
  123. int flags);
  124. /* supported object types */
  125. typedef enum json_type {
  126. /* If you change this, be sure to update json_type_to_name() too */
  127. json_type_null,
  128. json_type_boolean,
  129. json_type_double,
  130. json_type_int,
  131. json_type_object,
  132. json_type_array,
  133. json_type_string
  134. } json_type;
  135. /* reference counting functions */
  136. /**
  137. * Increment the reference count of json_object, thereby grabbing shared
  138. * ownership of obj.
  139. *
  140. * @param obj the json_object instance
  141. */
  142. extern struct json_object* json_object_get(struct json_object *obj);
  143. /**
  144. * Decrement the reference count of json_object and free if it reaches zero.
  145. * You must have ownership of obj prior to doing this or you will cause an
  146. * imbalance in the reference count.
  147. *
  148. * @param obj the json_object instance
  149. * @returns 1 if the object was freed.
  150. */
  151. int json_object_put(struct json_object *obj);
  152. /**
  153. * Check if the json_object is of a given type
  154. * @param obj the json_object instance
  155. * @param type one of:
  156. json_type_null (i.e. obj == NULL),
  157. json_type_boolean,
  158. json_type_double,
  159. json_type_int,
  160. json_type_object,
  161. json_type_array,
  162. json_type_string
  163. */
  164. extern int json_object_is_type(const struct json_object *obj, enum json_type type);
  165. /**
  166. * Get the type of the json_object. See also json_type_to_name() to turn this
  167. * into a string suitable, for instance, for logging.
  168. *
  169. * @param obj the json_object instance
  170. * @returns type being one of:
  171. json_type_null (i.e. obj == NULL),
  172. json_type_boolean,
  173. json_type_double,
  174. json_type_int,
  175. json_type_object,
  176. json_type_array,
  177. json_type_string
  178. */
  179. extern enum json_type json_object_get_type(const struct json_object *obj);
  180. /** Stringify object to json format.
  181. * Equivalent to json_object_to_json_string_ext(obj, JSON_C_TO_STRING_SPACED)
  182. * The pointer you get is an internal of your json object. You don't
  183. * have to free it, later use of json_object_put() should be sufficient.
  184. * If you can not ensure there's no concurrent access to *obj use
  185. * strdup().
  186. * @param obj the json_object instance
  187. * @returns a string in JSON format
  188. */
  189. extern const char* json_object_to_json_string(struct json_object *obj);
  190. /** Stringify object to json format
  191. * @see json_object_to_json_string() for details on how to free string.
  192. * @param obj the json_object instance
  193. * @param flags formatting options, see JSON_C_TO_STRING_PRETTY and other constants
  194. * @returns a string in JSON format
  195. */
  196. extern const char* json_object_to_json_string_ext(struct json_object *obj, int
  197. flags);
  198. /**
  199. * Set a custom serialization function to be used when this particular object
  200. * is converted to a string by json_object_to_json_string.
  201. *
  202. * If a custom serializer is already set on this object, any existing
  203. * user_delete function is called before the new one is set.
  204. *
  205. * If to_string_func is NULL, the other parameters are ignored
  206. * and the default behaviour is reset.
  207. *
  208. * The userdata parameter is optional and may be passed as NULL. If provided,
  209. * it is passed to to_string_func as-is. This parameter may be NULL even
  210. * if user_delete is non-NULL.
  211. *
  212. * The user_delete parameter is optional and may be passed as NULL, even if
  213. * the userdata parameter is non-NULL. It will be called just before the
  214. * json_object is deleted, after it's reference count goes to zero
  215. * (see json_object_put()).
  216. * If this is not provided, it is up to the caller to free the userdata at
  217. * an appropriate time. (i.e. after the json_object is deleted)
  218. *
  219. * @param jso the object to customize
  220. * @param to_string_func the custom serialization function
  221. * @param userdata an optional opaque cookie
  222. * @param user_delete an optional function from freeing userdata
  223. */
  224. extern void json_object_set_serializer(json_object *jso,
  225. json_object_to_json_string_fn to_string_func,
  226. void *userdata,
  227. json_object_delete_fn *user_delete);
  228. /**
  229. * Simply call free on the userdata pointer.
  230. * Can be used with json_object_set_serializer().
  231. *
  232. * @param jso unused
  233. * @param userdata the pointer that is passed to free().
  234. */
  235. json_object_delete_fn json_object_free_userdata;
  236. /**
  237. * Copy the jso->_userdata string over to pb as-is.
  238. * Can be used with json_object_set_serializer().
  239. *
  240. * @param jso The object whose _userdata is used.
  241. * @param pb The destination buffer.
  242. * @param level Ignored.
  243. * @param flags Ignored.
  244. */
  245. json_object_to_json_string_fn json_object_userdata_to_json_string;
  246. /* object type methods */
  247. /** Create a new empty object with a reference count of 1. The caller of
  248. * this object initially has sole ownership. Remember, when using
  249. * json_object_object_add or json_object_array_put_idx, ownership will
  250. * transfer to the object/array. Call json_object_get if you want to maintain
  251. * shared ownership or also add this object as a child of multiple objects or
  252. * arrays. Any ownerships you acquired but did not transfer must be released
  253. * through json_object_put.
  254. *
  255. * @returns a json_object of type json_type_object
  256. */
  257. extern struct json_object* json_object_new_object(void);
  258. /** Get the hashtable of a json_object of type json_type_object
  259. * @param obj the json_object instance
  260. * @returns a linkhash
  261. */
  262. extern struct lh_table* json_object_get_object(const struct json_object *obj);
  263. /** Get the size of an object in terms of the number of fields it has.
  264. * @param obj the json_object whose length to return
  265. */
  266. extern int json_object_object_length(const struct json_object* obj);
  267. /** Add an object field to a json_object of type json_type_object
  268. *
  269. * The reference count will *not* be incremented. This is to make adding
  270. * fields to objects in code more compact. If you want to retain a reference
  271. * to an added object, independent of the lifetime of obj, you must wrap the
  272. * passed object with json_object_get.
  273. *
  274. * Upon calling this, the ownership of val transfers to obj. Thus you must
  275. * make sure that you do in fact have ownership over this object. For instance,
  276. * json_object_new_object will give you ownership until you transfer it,
  277. * whereas json_object_object_get does not.
  278. *
  279. * @param obj the json_object instance
  280. * @param key the object field name (a private copy will be duplicated)
  281. * @param val a json_object or NULL member to associate with the given field
  282. *
  283. * @return On success, <code>0</code> is returned.
  284. * On error, a negative value is returned.
  285. */
  286. extern int json_object_object_add(struct json_object* obj, const char *key,
  287. struct json_object *val);
  288. /** Add an object field to a json_object of type json_type_object
  289. *
  290. * The semantics are identical to json_object_object_add, except that an
  291. * additional flag fields gives you more control over some detail aspects
  292. * of processing. See the description of JSON_C_OBJECT_ADD_* flags for more
  293. * details.
  294. *
  295. * @param obj the json_object instance
  296. * @param key the object field name (a private copy will be duplicated)
  297. * @param val a json_object or NULL member to associate with the given field
  298. * @param opts process-modifying options. To specify multiple options, use
  299. * arithmetic or (OPT1|OPT2)
  300. */
  301. extern void json_object_object_add_ex(struct json_object* obj, const char *key,
  302. struct json_object *val, const unsigned opts);
  303. /** Get the json_object associate with a given object field.
  304. *
  305. * This returns NULL if the field is found but its value is null, or if
  306. * the field is not found, or if obj is not a json_type_object. If you
  307. * need to distinguis between these cases, use json_object_object_get_ex().
  308. *
  309. * *No* reference counts will be changed. There is no need to manually adjust
  310. * reference counts through the json_object_put/json_object_get methods unless
  311. * you need to have the child (value) reference maintain a different lifetime
  312. * than the owning parent (obj). Ownership of the returned value is retained
  313. * by obj (do not do json_object_put unless you have done a json_object_get).
  314. * If you delete the value from obj (json_object_object_del) and wish to access
  315. * the returned reference afterwards, make sure you have first gotten shared
  316. * ownership through json_object_get (& don't forget to do a json_object_put
  317. * or transfer ownership to prevent a memory leak).
  318. *
  319. * @param obj the json_object instance
  320. * @param key the object field name
  321. * @returns the json_object associated with the given field name
  322. * @deprecated Please use json_object_object_get_ex
  323. */
  324. extern struct json_object* json_object_object_get(const struct json_object* obj,
  325. const char *key);
  326. /** Get the json_object associated with a given object field.
  327. *
  328. * This returns true if the key is found, false in all other cases (including
  329. * if obj isn't a json_type_object).
  330. *
  331. * *No* reference counts will be changed. There is no need to manually adjust
  332. * reference counts through the json_object_put/json_object_get methods unless
  333. * you need to have the child (value) reference maintain a different lifetime
  334. * than the owning parent (obj). Ownership of value is retained by obj.
  335. *
  336. * @param obj the json_object instance
  337. * @param key the object field name
  338. * @param value a pointer where to store a reference to the json_object
  339. * associated with the given field name.
  340. *
  341. * It is safe to pass a NULL value.
  342. * @returns whether or not the key exists
  343. */
  344. extern json_bool json_object_object_get_ex(const struct json_object* obj,
  345. const char *key,
  346. struct json_object **value);
  347. /** Delete the given json_object field
  348. *
  349. * The reference count will be decremented for the deleted object. If there
  350. * are no more owners of the value represented by this key, then the value is
  351. * freed. Otherwise, the reference to the value will remain in memory.
  352. *
  353. * @param obj the json_object instance
  354. * @param key the object field name
  355. */
  356. extern void json_object_object_del(struct json_object* obj, const char *key);
  357. /**
  358. * Iterate through all keys and values of an object.
  359. *
  360. * Adding keys to the object while iterating is NOT allowed.
  361. *
  362. * Deleting an existing key, or replacing an existing key with a
  363. * new value IS allowed.
  364. *
  365. * @param obj the json_object instance
  366. * @param key the local name for the char* key variable defined in the body
  367. * @param val the local name for the json_object* object variable defined in
  368. * the body
  369. */
  370. #if defined(__GNUC__) && !defined(__STRICT_ANSI__) && __STDC_VERSION__ >= 199901L
  371. # define json_object_object_foreach(obj,key,val) \
  372. char *key = NULL; \
  373. struct json_object *val __attribute__((__unused__)) = NULL; \
  374. for(struct lh_entry *entry ## key = json_object_get_object(obj)->head, *entry_next ## key = NULL; \
  375. ({ if(entry ## key) { \
  376. key = (char*)entry ## key->k; \
  377. val = (struct json_object*)entry ## key->v; \
  378. entry_next ## key = entry ## key->next; \
  379. } ; entry ## key; }); \
  380. entry ## key = entry_next ## key )
  381. #else /* ANSI C or MSC */
  382. # define json_object_object_foreach(obj,key,val) \
  383. char *key;\
  384. struct json_object *val; \
  385. struct lh_entry *entry ## key; \
  386. struct lh_entry *entry_next ## key = NULL; \
  387. for(entry ## key = json_object_get_object(obj)->head; \
  388. (entry ## key ? ( \
  389. key = (char*)entry ## key->k, \
  390. val = (struct json_object*)entry ## key->v, \
  391. entry_next ## key = entry ## key->next, \
  392. entry ## key) : 0); \
  393. entry ## key = entry_next ## key)
  394. #endif /* defined(__GNUC__) && !defined(__STRICT_ANSI__) && __STDC_VERSION__ >= 199901L */
  395. /** Iterate through all keys and values of an object (ANSI C Safe)
  396. * @param obj the json_object instance
  397. * @param iter the object iterator
  398. */
  399. #define json_object_object_foreachC(obj,iter) \
  400. for(iter.entry = json_object_get_object(obj)->head; (iter.entry ? (iter.key = (char*)iter.entry->k, iter.val = (struct json_object*)iter.entry->v, iter.entry) : 0); iter.entry = iter.entry->next)
  401. /* Array type methods */
  402. /** Create a new empty json_object of type json_type_array
  403. * @returns a json_object of type json_type_array
  404. */
  405. extern struct json_object* json_object_new_array(void);
  406. /** Get the arraylist of a json_object of type json_type_array
  407. * @param obj the json_object instance
  408. * @returns an arraylist
  409. */
  410. extern struct array_list* json_object_get_array(const struct json_object *obj);
  411. /** Get the length of a json_object of type json_type_array
  412. * @param obj the json_object instance
  413. * @returns an int
  414. */
  415. extern size_t json_object_array_length(const struct json_object *obj);
  416. /** Sorts the elements of jso of type json_type_array
  417. *
  418. * Pointers to the json_object pointers will be passed as the two arguments
  419. * to @sort_fn
  420. *
  421. * @param obj the json_object instance
  422. * @param sort_fn a sorting function
  423. */
  424. extern void json_object_array_sort(struct json_object *jso, int(*sort_fn)(const void *, const void *));
  425. /** Binary search a sorted array for a specified key object.
  426. *
  427. * It depends on your compare function what's sufficient as a key.
  428. * Usually you create some dummy object with the parameter compared in
  429. * it, to identify the right item you're actually looking for.
  430. *
  431. * @see json_object_array_sort() for hints on the compare function.
  432. *
  433. * @param key a dummy json_object with the right key
  434. * @param jso the array object we're searching
  435. * @param sort_fn the sort/compare function
  436. *
  437. * @return the wanted json_object instance
  438. */
  439. extern struct json_object* json_object_array_bsearch(
  440. const struct json_object *key,
  441. const struct json_object *jso,
  442. int (*sort_fn)(const void *, const void *));
  443. /** Add an element to the end of a json_object of type json_type_array
  444. *
  445. * The reference count will *not* be incremented. This is to make adding
  446. * fields to objects in code more compact. If you want to retain a reference
  447. * to an added object you must wrap the passed object with json_object_get
  448. *
  449. * @param obj the json_object instance
  450. * @param val the json_object to be added
  451. */
  452. extern int json_object_array_add(struct json_object *obj,
  453. struct json_object *val);
  454. /** Insert or replace an element at a specified index in an array (a json_object of type json_type_array)
  455. *
  456. * The reference count will *not* be incremented. This is to make adding
  457. * fields to objects in code more compact. If you want to retain a reference
  458. * to an added object you must wrap the passed object with json_object_get
  459. *
  460. * The reference count of a replaced object will be decremented.
  461. *
  462. * The array size will be automatically be expanded to the size of the
  463. * index if the index is larger than the current size.
  464. *
  465. * @param obj the json_object instance
  466. * @param idx the index to insert the element at
  467. * @param val the json_object to be added
  468. */
  469. extern int json_object_array_put_idx(struct json_object *obj, size_t idx,
  470. struct json_object *val);
  471. /** Get the element at specificed index of the array (a json_object of type json_type_array)
  472. * @param obj the json_object instance
  473. * @param idx the index to get the element at
  474. * @returns the json_object at the specified index (or NULL)
  475. */
  476. extern struct json_object* json_object_array_get_idx(const struct json_object *obj,
  477. size_t idx);
  478. /** Delete an elements from a specified index in an array (a json_object of type json_type_array)
  479. *
  480. * The reference count will be decremented for each of the deleted objects. If there
  481. * are no more owners of an element that is being deleted, then the value is
  482. * freed. Otherwise, the reference to the value will remain in memory.
  483. *
  484. * @param obj the json_object instance
  485. * @param idx the index to start deleting elements at
  486. * @param count the number of elements to delete
  487. * @returns 0 if the elements were successfully deleted
  488. */
  489. extern int json_object_array_del_idx(struct json_object *obj, size_t idx, size_t count);
  490. /* json_bool type methods */
  491. /** Create a new empty json_object of type json_type_boolean
  492. * @param b a json_bool TRUE or FALSE (1 or 0)
  493. * @returns a json_object of type json_type_boolean
  494. */
  495. extern struct json_object* json_object_new_boolean(json_bool b);
  496. /** Get the json_bool value of a json_object
  497. *
  498. * The type is coerced to a json_bool if the passed object is not a json_bool.
  499. * integer and double objects will return FALSE if there value is zero
  500. * or TRUE otherwise. If the passed object is a string it will return
  501. * TRUE if it has a non zero length. If any other object type is passed
  502. * TRUE will be returned if the object is not NULL.
  503. *
  504. * @param obj the json_object instance
  505. * @returns a json_bool
  506. */
  507. extern json_bool json_object_get_boolean(const struct json_object *obj);
  508. /* int type methods */
  509. /** Create a new empty json_object of type json_type_int
  510. * Note that values are stored as 64-bit values internally.
  511. * To ensure the full range is maintained, use json_object_new_int64 instead.
  512. * @param i the integer
  513. * @returns a json_object of type json_type_int
  514. */
  515. extern struct json_object* json_object_new_int(int32_t i);
  516. /** Create a new empty json_object of type json_type_int
  517. * @param i the integer
  518. * @returns a json_object of type json_type_int
  519. */
  520. extern struct json_object* json_object_new_int64(int64_t i);
  521. /** Get the int value of a json_object
  522. *
  523. * The type is coerced to a int if the passed object is not a int.
  524. * double objects will return their integer conversion. Strings will be
  525. * parsed as an integer. If no conversion exists then 0 is returned
  526. * and errno is set to EINVAL. null is equivalent to 0 (no error values set)
  527. *
  528. * Note that integers are stored internally as 64-bit values.
  529. * If the value of too big or too small to fit into 32-bit, INT32_MAX or
  530. * INT32_MIN are returned, respectively.
  531. *
  532. * @param obj the json_object instance
  533. * @returns an int
  534. */
  535. extern int32_t json_object_get_int(const struct json_object *obj);
  536. /** Get the int value of a json_object
  537. *
  538. * The type is coerced to a int64 if the passed object is not a int64.
  539. * double objects will return their int64 conversion. Strings will be
  540. * parsed as an int64. If no conversion exists then 0 is returned.
  541. *
  542. * NOTE: Set errno to 0 directly before a call to this function to determine
  543. * whether or not conversion was successful (it does not clear the value for
  544. * you).
  545. *
  546. * @param obj the json_object instance
  547. * @returns an int64
  548. */
  549. extern int64_t json_object_get_int64(const struct json_object *obj);
  550. /* double type methods */
  551. /** Create a new empty json_object of type json_type_double
  552. *
  553. * @see json_object_double_to_json_string() for how to set a custom format string.
  554. *
  555. * @param d the double
  556. * @returns a json_object of type json_type_double
  557. */
  558. extern struct json_object* json_object_new_double(double d);
  559. /**
  560. * Create a new json_object of type json_type_double, using
  561. * the exact serialized representation of the value.
  562. *
  563. * This allows for numbers that would otherwise get displayed
  564. * inefficiently (e.g. 12.3 => "12.300000000000001") to be
  565. * serialized with the more convenient form.
  566. *
  567. * Note: this is used by json_tokener_parse_ex() to allow for
  568. * an exact re-serialization of a parsed object.
  569. *
  570. * An equivalent sequence of calls is:
  571. * @code
  572. * jso = json_object_new_double(d);
  573. * json_object_set_serializer(jso, json_object_userdata_to_json_string,
  574. * strdup(ds), json_object_free_userdata);
  575. * @endcode
  576. *
  577. * @param d the numeric value of the double.
  578. * @param ds the string representation of the double. This will be copied.
  579. */
  580. extern struct json_object* json_object_new_double_s(double d, const char *ds);
  581. /** Serialize a json_object of type json_type_double to a string.
  582. *
  583. * This function isn't meant to be called directly. Instead, you can set a
  584. * custom format string for the serialization of this double using the
  585. * following call (where "%.17g" actually is the default):
  586. *
  587. * @code
  588. * jso = json_object_new_double(d);
  589. * json_object_set_serializer(jso, json_object_double_to_json_string,
  590. * "%.17g", NULL);
  591. * @endcode
  592. *
  593. * @see printf(3) man page for format strings
  594. *
  595. * @param jso The json_type_double object that is serialized.
  596. * @param pb The destination buffer.
  597. * @param level Ignored.
  598. * @param flags Ignored.
  599. */
  600. extern int json_object_double_to_json_string(struct json_object* jso,
  601. struct printbuf *pb,
  602. int level,
  603. int flags);
  604. /** Get the double floating point value of a json_object
  605. *
  606. * The type is coerced to a double if the passed object is not a double.
  607. * integer objects will return their double conversion. Strings will be
  608. * parsed as a double. If no conversion exists then 0.0 is returned and
  609. * errno is set to EINVAL. null is equivalent to 0 (no error values set)
  610. *
  611. * If the value is too big to fit in a double, then the value is set to
  612. * the closest infinity with errno set to ERANGE. If strings cannot be
  613. * converted to their double value, then EINVAL is set & NaN is returned.
  614. *
  615. * Arrays of length 0 are interpreted as 0 (with no error flags set).
  616. * Arrays of length 1 are effectively cast to the equivalent object and
  617. * converted using the above rules. All other arrays set the error to
  618. * EINVAL & return NaN.
  619. *
  620. * NOTE: Set errno to 0 directly before a call to this function to
  621. * determine whether or not conversion was successful (it does not clear
  622. * the value for you).
  623. *
  624. * @param obj the json_object instance
  625. * @returns a double floating point number
  626. */
  627. extern double json_object_get_double(const struct json_object *obj);
  628. /* string type methods */
  629. /** Create a new empty json_object of type json_type_string
  630. *
  631. * A copy of the string is made and the memory is managed by the json_object
  632. *
  633. * @param s the string
  634. * @returns a json_object of type json_type_string
  635. */
  636. extern struct json_object* json_object_new_string(const char *s);
  637. extern struct json_object* json_object_new_string_len(const char *s, int len);
  638. /** Get the string value of a json_object
  639. *
  640. * If the passed object is of type json_type_null (i.e. obj == NULL),
  641. * NULL is returned.
  642. *
  643. * If the passed object of type json_type_string, the string contents
  644. * are returned.
  645. *
  646. * Otherwise the JSON representation of the object is returned.
  647. *
  648. * The returned string memory is managed by the json_object and will
  649. * be freed when the reference count of the json_object drops to zero.
  650. *
  651. * @param obj the json_object instance
  652. * @returns a string or NULL
  653. */
  654. extern const char* json_object_get_string(struct json_object *obj);
  655. /** Get the string length of a json_object
  656. *
  657. * If the passed object is not of type json_type_string then zero
  658. * will be returned.
  659. *
  660. * @param obj the json_object instance
  661. * @returns int
  662. */
  663. extern int json_object_get_string_len(const struct json_object *obj);
  664. /** Check if two json_object's are equal
  665. *
  666. * If the passed objects are equal 1 will be returned.
  667. * Equality is defined as follows:
  668. * - json_objects of different types are never equal
  669. * - json_objects of the same primitive type are equal if the
  670. * c-representation of their value is equal
  671. * - json-arrays are considered equal if all values at the same
  672. * indices are equal (same order)
  673. * - Complex json_objects are considered equal if all
  674. * contained objects referenced by their key are equal,
  675. * regardless their order.
  676. *
  677. * @param obj1 the first json_object instance
  678. * @param obj2 the second json_object instance
  679. * @returns whether both objects are equal or not
  680. */
  681. extern int json_object_equal(struct json_object *obj1,
  682. struct json_object *obj2);
  683. #ifdef __cplusplus
  684. }
  685. #endif
  686. #endif