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_reset ucw_json_reset
32 #define json_set_input ucw_json_set_input
33 #define json_set_output ucw_json_set_output
34 #define json_write ucw_json_write
35 #define json_write_value ucw_json_write_value
39 * === JSON library context
41 * FIXME: Document memory management
45 * The context is represented a pointer to this structure.
46 * The fields marked with [*] are publicly accessible, the rest is private.
51 struct mempool_state init_state;
54 struct fastbuf *in_fb;
55 uint in_line; // [*] Current line number
56 uint in_column; // [*] Current column number
57 bool in_eof; // End of file was encountered
58 struct json_node *next_token;
59 struct json_node *trivial_token;
63 struct fastbuf *out_fb;
65 uint format_options; // [*] Formatting options (a combination of JSON_FORMAT_xxx)
68 /** Creates a new JSON context. **/
69 struct json_context *json_new(void);
71 /** Deletes a JSON context, deallocating all memory associated with it. **/
72 void json_delete(struct json_context *js);
75 * Recycles a JSON context. All state is reset, allocated objects are freed.
76 * This is equivalent to mp_delete() followed by mp_new(), but it is faster
77 * and the address of the context is preserved.
79 void json_reset(struct json_context *js);
84 * Each JSON value is represented by <<struct json_node,struct json_node>>,
85 * which is either an elementary value (null, boolean, number, string),
86 * or a container (array, object) pointing to other values.
88 * A value can belong to multiple containers simultaneously, so in general,
89 * the relationships between values need not form a tree, but a directed
92 * You are allowed to read contents of nodes directly, but construction
93 * and modification of nodes must be always performed using the appropriate
106 // These are not real nodes, but raw tokens.
107 // They are not present in the tree of values, but you may see them
108 // if you call json_next_token() and friends.
118 /** Each value is represented by a single node. **/
120 enum json_node_type type;
121 union { // Data specific to individual value types
125 struct json_node **elements; // Arrays: Growing array of values
126 struct json_pair *pairs; // Objects: Growing array of pairs
130 /** Attributes of objects are stored as (key, value) pairs of this format. **/
133 struct json_node *value;
138 struct json_node *json_new_node(struct json_context *js, enum json_node_type type);
140 /** Creates a new null value. **/
141 static inline struct json_node *json_new_null(struct json_context *js)
143 return json_new_node(js, JSON_NULL);
146 /** Creates a new boolean value. **/
147 static inline struct json_node *json_new_bool(struct json_context *js, bool value)
149 struct json_node *n = json_new_node(js, JSON_BOOLEAN);
154 /** Creates a new numeric value. **/
155 static inline struct json_node *json_new_number(struct json_context *js, double value)
157 struct json_node *n = json_new_node(js, JSON_NUMBER);
162 /** Creates a new string value. The @value is kept only as a reference. **/
163 static inline struct json_node *json_new_string_ref(struct json_context *js, const char *value)
165 struct json_node *n = json_new_node(js, JSON_STRING);
170 /** Creates a new string value, making a private copy of @value. **/
171 static inline struct json_node *json_new_string(struct json_context *js, const char *value)
173 return json_new_string_ref(js, mp_strdup(js->pool, value));
176 /** Creates a new array value with no elements. **/
177 struct json_node *json_new_array(struct json_context *js);
179 /** Appends a new element to the given array. **/
180 void json_array_append(struct json_node *array, struct json_node *elt);
182 /** Creates a new object value with no attributes. **/
183 struct json_node *json_new_object(struct json_context *js);
186 * Adds a new (@key, @value) pair to the given object. If @key is already
187 * present, the pair is replaced. If @value is NULL, no new pair is created
188 * and a pre-existing pair is deleted.
190 * The @key is referenced by the object, you must not free it during
191 * the lifetime of the JSON context.
193 * FIXME: Add json_copy_key().
195 void json_object_set(struct json_node *n, const char *key, struct json_node *value);
197 /** Returns the value associated with @key, or NULL if no such value exists. **/
198 struct json_node *json_object_get(struct json_node *n, const char *key);
203 * The simplest way to parse a complete JSON file is to call json_parse(),
204 * which returns a value tree representing the contents of the file.
206 * Alternatively, you can read the input token by token: call json_set_input()
207 * and then repeat json_next_token(). Note that even in this mode, the tokens
208 * are kept in memory. (If you need to parse huge JSON files, please ask the
209 * maintainer of this library to improve memory allocation.)
212 /** Parses a JSON file from the given fastbuf stream. **/
213 struct json_node *json_parse(struct json_context *js, struct fastbuf *fb);
215 /** Selects the given fastbuf stream as parser input. **/
216 void json_set_input(struct json_context *js, struct fastbuf *in);
218 /** Reads the next token from the input. **/
219 struct json_node *json_next_token(struct json_context *js);
221 /** Reads the next token, but keeps it in the input. **/
222 struct json_node *json_peek_token(struct json_context *js);
224 /** Reads the next JSON value, including nested values. **/
225 struct json_node *json_next_value(struct json_context *js);
230 * JSON files can be produced by simply calling json_write().
232 * If you want to generate the output on the fly (for example if it is huge),
233 * call json_set_output() and then iterate json_write_value().
235 * By default, we produce a single-line compact representation,
236 * but you can choose differently by setting the appropriate
237 * `format_options` in the `json_context`.
240 /** Writes a JSON file to the given fastbuf stream, containing the JSON value @n. **/
241 void json_write(struct json_context *js, struct fastbuf *fb, struct json_node *n);
243 /** Selects the given fastbuf stream as output. **/
244 void json_set_output(struct json_context *js, struct fastbuf *fb);
246 /** Writes a single JSON value to the output stream. **/
247 void json_write_value(struct json_context *js, struct json_node *n);
249 /** Formatting options. The `format_options` field in the context is a bitwise OR of these flags. **/
250 enum json_format_option {
251 JSON_FORMAT_ESCAPE_NONASCII = 1, // Produce pure ASCII output by escaping all Unicode characters in strings
252 JSON_FORMAT_INDENT = 2, // Produce pretty indented output