4 * (c) 2015 Martin Mares <mj@ucw.cz>
6 * This software may be freely distributed and used according to the terms
7 * of the GNU Lesser General Public License.
10 #ifndef _UCW_JSON_JSON_H
11 #define _UCW_JSON_JSON_H
13 #include <ucw/clists.h>
14 #include <ucw/slists.h>
15 #include <ucw/mempool.h>
16 #include <ucw/fastbuf.h>
18 #ifdef CONFIG_UCW_CLEAN_ABI
19 #define json_array_append ucw_json_array_append
20 #define json_delete ucw_json_delete
21 #define json_new ucw_json_new
22 #define json_new_array ucw_json_new_array
23 #define json_new_node ucw_json_new_node
24 #define json_new_object ucw_json_new_object
25 #define json_next_token ucw_json_next_token
26 #define json_next_value ucw_json_next_value
27 #define json_object_get ucw_json_object_get
28 #define json_object_set ucw_json_object_set
29 #define json_parse ucw_json_parse
30 #define json_peek_token ucw_json_peek_token
31 #define json_pop ucw_json_pop
32 #define json_push ucw_json_push
33 #define json_reset ucw_json_reset
34 #define json_set_input ucw_json_set_input
35 #define json_set_output ucw_json_set_output
36 #define json_write ucw_json_write
37 #define json_write_value ucw_json_write_value
41 * === JSON library context
43 * The context structure remembers the whole state of the JSON
44 * library. All JSON values are allocated from a memory pool associated
45 * with the context. By default, their lifetime is the same as that
48 * Alternatively, you can mark the current state of the context
49 * with json_push() and return to the marked state later using
50 * json_pop(). All JSON values created between these two operations
51 * are released afterwards. See json_push() for details.
55 * The context is represented a pointer to this structure.
56 * The fields marked with [*] are publicly accessible, the rest is private.
61 struct mempool_state init_state;
64 struct fastbuf *in_fb;
65 uint in_line; // [*] Current line number
66 uint in_column; // [*] Current column number
67 bool in_eof; // End of file was encountered
68 struct json_node *next_token;
69 struct json_node *trivial_token;
73 struct fastbuf *out_fb;
75 uint format_options; // [*] Formatting options (a combination of JSON_FORMAT_xxx)
78 /** Creates a new JSON context. **/
79 struct json_context *json_new(void);
81 /** Deletes a JSON context, deallocating all memory associated with it. **/
82 void json_delete(struct json_context *js);
85 * Recycles a JSON context. All state is reset, allocated objects are freed.
86 * This is equivalent to mp_delete() followed by mp_new(), but it is faster
87 * and the address of the context is preserved.
89 void json_reset(struct json_context *js);
92 * Push the current state of the context onto state stack.
94 * Between json_push() and the associated json_pop(), only newly
95 * created JSON values can be modified. Older values can be only
96 * inspected, never modified. In particular, new values cannot be
97 * inserted to old arrays nor objects.
99 * If you are using json_peek_token(), the saved tokens cannot
100 * be carried over push/pop boundary.
102 void json_push(struct json_context *js);
105 * Pop state of the context off state stack. All JSON values created
106 * since the state was saved by json_push() are released.
108 void json_pop(struct json_context *js);
113 * Each JSON value is represented by <<struct json_node,struct json_node>>,
114 * which is either an elementary value (null, boolean, number, string),
115 * or a container (array, object) pointing to other values.
117 * A value can belong to multiple containers simultaneously, so in general,
118 * the relationships between values need not form a tree, but a directed
121 * You are allowed to read contents of nodes directly, but construction
122 * and modification of nodes must be always performed using the appropriate
127 enum json_node_type {
135 // These are not real nodes, but raw tokens.
136 // They are not present in the tree of values, but you may see them
137 // if you call json_next_token() and friends.
147 /** Each value is represented by a single node. **/
149 enum json_node_type type;
150 union { // Data specific to individual value types
154 struct json_node **elements; // Arrays: Growing array of values
155 struct json_pair *pairs; // Objects: Growing array of pairs
159 /** Attributes of objects are stored as (key, value) pairs of this format. **/
162 struct json_node *value;
167 struct json_node *json_new_node(struct json_context *js, enum json_node_type type);
169 /** Creates a new null value. **/
170 static inline struct json_node *json_new_null(struct json_context *js)
172 return json_new_node(js, JSON_NULL);
175 /** Creates a new boolean value. **/
176 static inline struct json_node *json_new_bool(struct json_context *js, bool value)
178 struct json_node *n = json_new_node(js, JSON_BOOLEAN);
183 /** Creates a new numeric value. **/
184 static inline struct json_node *json_new_number(struct json_context *js, double value)
186 struct json_node *n = json_new_node(js, JSON_NUMBER);
191 /** Creates a new string value. The @value is kept only as a reference. **/
192 static inline struct json_node *json_new_string_ref(struct json_context *js, const char *value)
194 struct json_node *n = json_new_node(js, JSON_STRING);
199 /** Creates a new string value, making a private copy of @value. **/
200 static inline struct json_node *json_new_string(struct json_context *js, const char *value)
202 return json_new_string_ref(js, mp_strdup(js->pool, value));
205 /** Creates a new array value with no elements. **/
206 struct json_node *json_new_array(struct json_context *js);
208 /** Appends a new element to the given array. **/
209 void json_array_append(struct json_node *array, struct json_node *elt);
211 /** Creates a new object value with no attributes. **/
212 struct json_node *json_new_object(struct json_context *js);
215 * Adds a new (@key, @value) pair to the given object. If @key is already
216 * present, the pair is replaced. If @value is NULL, no new pair is created
217 * and a pre-existing pair is deleted.
219 * The @key is referenced by the object, you must not free it during
220 * the lifetime of the JSON context.
222 * FIXME: Add json_copy_key().
224 void json_object_set(struct json_node *n, const char *key, struct json_node *value);
226 /** Returns the value associated with @key, or NULL if no such value exists. **/
227 struct json_node *json_object_get(struct json_node *n, const char *key);
232 * The simplest way to parse a complete JSON file is to call json_parse(),
233 * which returns a value tree representing the contents of the file.
235 * Alternatively, you can read the input token by token: call json_set_input()
236 * and then repeat json_next_token(). If you are parsing huge JSON files,
237 * you probably want to do json_push() first, then scan and process some
238 * tokens, and then json_pop().
241 /** Parses a JSON file from the given fastbuf stream. **/
242 struct json_node *json_parse(struct json_context *js, struct fastbuf *fb);
244 /** Selects the given fastbuf stream as parser input. **/
245 void json_set_input(struct json_context *js, struct fastbuf *in);
247 /** Reads the next token from the input. **/
248 struct json_node *json_next_token(struct json_context *js);
250 /** Reads the next token, but keeps it in the input. **/
251 struct json_node *json_peek_token(struct json_context *js);
253 /** Reads the next JSON value, including nested values. **/
254 struct json_node *json_next_value(struct json_context *js);
259 * JSON files can be produced by simply calling json_write().
261 * If you want to generate the output on the fly (for example if it is huge),
262 * call json_set_output() and then iterate json_write_value().
264 * By default, we produce a single-line compact representation,
265 * but you can choose differently by setting the appropriate
266 * `format_options` in the `json_context`.
269 /** Writes a JSON file to the given fastbuf stream, containing the JSON value @n. **/
270 void json_write(struct json_context *js, struct fastbuf *fb, struct json_node *n);
272 /** Selects the given fastbuf stream as output. **/
273 void json_set_output(struct json_context *js, struct fastbuf *fb);
275 /** Writes a single JSON value to the output stream. **/
276 void json_write_value(struct json_context *js, struct json_node *n);
278 /** Formatting options. The `format_options` field in the context is a bitwise OR of these flags. **/
279 enum json_format_option {
280 JSON_FORMAT_ESCAPE_NONASCII = 1, // Produce pure ASCII output by escaping all Unicode characters in strings
281 JSON_FORMAT_INDENT = 2, // Produce pretty indented output