2 * $Id: json_tokener.h,v 1.10 2006/07/25 03:24:50 mclark Exp $
4 * Copyright (c) 2004, 2005 Metaparadigm Pte. Ltd.
5 * Michael Clark <michael@metaparadigm.com>
7 * This library is free software; you can redistribute it and/or modify
8 * it under the terms of the MIT license. See COPYING for details.
12 #ifndef _json_tokener_h_
13 #define _json_tokener_h_
16 #include "json_object.h"
22 enum json_tokener_error {
24 json_tokener_continue,
25 json_tokener_error_depth,
26 json_tokener_error_parse_eof,
27 json_tokener_error_parse_unexpected,
28 json_tokener_error_parse_null,
29 json_tokener_error_parse_boolean,
30 json_tokener_error_parse_number,
31 json_tokener_error_parse_array,
32 json_tokener_error_parse_object_key_name,
33 json_tokener_error_parse_object_key_sep,
34 json_tokener_error_parse_object_value_sep,
35 json_tokener_error_parse_string,
36 json_tokener_error_parse_comment
39 enum json_tokener_state {
40 json_tokener_state_eatws,
41 json_tokener_state_start,
42 json_tokener_state_finish,
43 json_tokener_state_null,
44 json_tokener_state_comment_start,
45 json_tokener_state_comment,
46 json_tokener_state_comment_eol,
47 json_tokener_state_comment_end,
48 json_tokener_state_string,
49 json_tokener_state_string_escape,
50 json_tokener_state_escape_unicode,
51 json_tokener_state_boolean,
52 json_tokener_state_number,
53 json_tokener_state_array,
54 json_tokener_state_array_add,
55 json_tokener_state_array_sep,
56 json_tokener_state_object_field_start,
57 json_tokener_state_object_field,
58 json_tokener_state_object_field_end,
59 json_tokener_state_object_value,
60 json_tokener_state_object_value_add,
61 json_tokener_state_object_sep
64 struct json_tokener_srec
66 enum json_tokener_state state, saved_state;
67 struct json_object *obj;
68 struct json_object *current;
72 #define JSON_TOKENER_MAX_DEPTH 32
78 int depth, is_double, st_pos, char_offset;
79 enum json_tokener_error err;
80 unsigned int ucs_char;
82 struct json_tokener_srec stack[JSON_TOKENER_MAX_DEPTH];
86 * Given an error previously returned by json_tokener_get_error(),
87 * return a human readable description of the error.
89 * @return a generic error message is returned if an invalid error value is provided.
91 const char *json_tokener_error_desc(enum json_tokener_error jerr);
94 * @b XXX do not use json_tokener_errors directly.
95 * After v0.10 this will be removed.
97 * See json_tokener_error_desc() instead.
99 extern const char* json_tokener_errors[];
102 * Retrieve the error caused by the last call to json_tokener_parse_ex(),
103 * or json_tokener_success if there is no error.
105 * When parsing a JSON string in pieces, if the tokener is in the middle
106 * of parsing this will return json_tokener_continue.
108 * See also json_tokener_error_desc().
110 enum json_tokener_error json_tokener_get_error(struct json_tokener *tok);
112 extern struct json_tokener* json_tokener_new(void);
113 extern void json_tokener_free(struct json_tokener *tok);
114 extern void json_tokener_reset(struct json_tokener *tok);
115 extern struct json_object* json_tokener_parse(const char *str);
116 extern struct json_object* json_tokener_parse_verbose(const char *str, enum json_tokener_error *error);
119 * Parse a string and return a non-NULL json_object if a valid JSON value
120 * is found. The string does not need to be a JSON object or array;
121 * it can also be a string, number or boolean value.
123 * A partial JSON string can be parsed. If the parsing is incomplete,
124 * NULL will be returned and json_tokener_get_error() will be return
125 * json_tokener_continue.
126 * json_tokener_parse_ex() can then be called with additional bytes in str
127 * to continue the parsing.
129 * If json_tokener_parse_ex() returns NULL and the error anything other than
130 * json_tokener_continue, a fatal error has occurred and parsing must be
131 * halted. Then tok object must not be re-used until json_tokener_reset() is
134 * When a valid JSON value is parsed, a non-NULL json_object will be
135 * returned. Also, json_tokener_get_error() will return json_tokener_success.
136 * Be sure to check the type with json_object_is_type() or
137 * json_object_get_type() before using the object.
139 * @b XXX this shouldn't use internal fields:
140 * Trailing characters after the parsed value do not automatically cause an
141 * error. It is up to the caller to decide whether to treat this as an
142 * error or to handle the additional characters, perhaps by parsing another
143 * json value starting from that point.
145 * Extra characters can be detected by comparing the tok->char_offset against
146 * the length of the last len parameter passed in.
148 * The tokener does \b not maintain an internal buffer so the caller is
149 * responsible for calling json_tokener_parse_ex with an appropriate str
150 * parameter starting with the extra characters.
154 json_object *jobj = NULL;
155 const char *mystring = NULL;
157 enum json_tokener_error jerr;
159 mystring = ... // get JSON string, e.g. read from file, etc...
160 stringlen = strlen(mystring);
161 jobj = json_tokener_parse_ex(tok, mystring, stringlen);
162 } while ((jerr = json_tokener_get_error(tok)) == json_tokener_continue);
163 if (jerr != json_tokener_success)
165 fprintf(stderr, "Error: %s\n", json_tokener_error_desc(jerr));
166 // Handle errors, as appropriate for your application.
168 if (tok->char_offset < stringlen) // XXX shouldn't access internal fields
170 // Handle extra characters after parsed object as desired.
171 // e.g. issue an error, parse another object from that point, etc...
173 // Success, use jobj here.
177 * @param tok a json_tokener previously allocated with json_tokener_new()
178 * @param str an string with any valid JSON expression, or portion of. This does not need to be null terminated.
179 * @param len the length of str
181 extern struct json_object* json_tokener_parse_ex(struct json_tokener *tok,
182 const char *str, int len);