json_tokener.h File Reference

Methods to parse an input string into a tree of json_object objects. More...

## Data Structures

struct | json_tokener_srec
struct | json_tokener

## Macros

#define | JSON_TOKENER_DEFAULT_DEPTH 32
#define | JSON_TOKENER_STRICT 0x01

## Typedefs

typedef struct json_tokener | json_tokener

## Enumerations

enum

json_tokener_error {
json_tokener_success, json_tokener_continue, json_tokener_error_depth, json_tokener_error_parse_eof,
json_tokener_error_parse_unexpected, json_tokener_error_parse_null, json_tokener_error_parse_boolean, json_tokener_error_parse_number,
json_tokener_error_parse_array, json_tokener_error_parse_object_key_name, json_tokener_error_parse_object_key_sep, json_tokener_error_parse_object_value_sep,
json_tokener_error_parse_string, json_tokener_error_parse_comment, json_tokener_error_size
}

enum

json_tokener_state {
json_tokener_state_eatws, json_tokener_state_start, json_tokener_state_finish, json_tokener_state_null,
json_tokener_state_comment_start, json_tokener_state_comment, json_tokener_state_comment_eol, json_tokener_state_comment_end,
json_tokener_state_string, json_tokener_state_string_escape, json_tokener_state_escape_unicode, json_tokener_state_boolean,
json_tokener_state_number, json_tokener_state_array, json_tokener_state_array_add, json_tokener_state_array_sep,
json_tokener_state_object_field_start, json_tokener_state_object_field, json_tokener_state_object_field_end, json_tokener_state_object_value,
json_tokener_state_object_value_add, json_tokener_state_object_sep, json_tokener_state_array_after_sep, json_tokener_state_object_field_start_after_sep,
json_tokener_state_inf
}

## Functions

const char * | json_tokener_error_desc (enum json_tokener_error jerr)
JSON_EXPORT enum json_tokener_error | json_tokener_get_error (struct json_tokener *tok)
JSON_EXPORT struct json_tokener * | json_tokener_new (void)
JSON_EXPORT struct json_tokener * | json_tokener_new_ex (int depth)
JSON_EXPORT void | json_tokener_free (struct json_tokener *tok)
JSON_EXPORT void | json_tokener_reset (struct json_tokener *tok)
JSON_EXPORT struct json_object * | json_tokener_parse (const char *str)
JSON_EXPORT struct json_object * | json_tokener_parse_verbose (const char *str, enum json_tokener_error *error)
JSON_EXPORT void | json_tokener_set_flags (struct json_tokener *tok, int flags)
JSON_EXPORT struct json_object * | json_tokener_parse_ex (struct json_tokener *tok, const char *str, int len)

## Detailed Description

Methods to parse an input string into a tree of json_object objects.

## Macro Definition Documentation

#define JSON_TOKENER_DEFAULT_DEPTH 32

#define JSON_TOKENER_STRICT 0x01

Be strict when parsing JSON input. Use caution with this flag as what is considered valid may become more restrictive from one release to the next, causing your code to fail on previously working input.

This flag is not set by default.

See also
  json_tokener_set_flags()

## Typedef Documentation

typedef struct json_tokener json_tokener

Deprecated:
  Unused in json-c code

## Enumeration Type Documentation

enum json_tokener_error

Enumerator
json_tokener_success |
json_tokener_continue |
json_tokener_error_depth |
json_tokener_error_parse_eof |
json_tokener_error_parse_unexpected |
json_tokener_error_parse_null |
json_tokener_error_parse_boolean |
json_tokener_error_parse_number |
json_tokener_error_parse_array |
json_tokener_error_parse_object_key_name |
json_tokener_error_parse_object_key_sep |
json_tokener_error_parse_object_value_sep |
json_tokener_error_parse_string |
json_tokener_error_parse_comment |
json_tokener_error_size |

enum json_tokener_state

Enumerator
json_tokener_state_eatws |
json_tokener_state_start |
json_tokener_state_finish |
json_tokener_state_null |
json_tokener_state_comment_start |
json_tokener_state_comment |
json_tokener_state_comment_eol |
json_tokener_state_comment_end |
json_tokener_state_string |
json_tokener_state_string_escape |
json_tokener_state_escape_unicode |
json_tokener_state_boolean |
json_tokener_state_number |
json_tokener_state_array |
json_tokener_state_array_add |
json_tokener_state_array_sep |
json_tokener_state_object_field_start |
json_tokener_state_object_field |
json_tokener_state_object_field_end |
json_tokener_state_object_value |
json_tokener_state_object_value_add |
json_tokener_state_object_sep |
json_tokener_state_array_after_sep |
json_tokener_state_object_field_start_after_sep |
json_tokener_state_inf |

## Function Documentation

const char* json_tokener_error_desc | ( | enum json_tokener_error | jerr | ) |

Given an error previously returned by json_tokener_get_error(), return a human readable description of the error.

Returns
  a generic error message is returned if an invalid error value is provided.

JSON_EXPORT void json_tokener_free | ( | struct json_tokener * | tok | ) |

JSON_EXPORT enum json_tokener_error json_tokener_get_error | ( | struct json_tokener * | tok | ) |

Retrieve the error caused by the last call to json_tokener_parse_ex(), or json_tokener_success if there is no error.

When parsing a JSON string in pieces, if the tokener is in the middle of parsing this will return json_tokener_continue.

See also json_tokener_error_desc().

JSON_EXPORT struct json_tokener* json_tokener_new | ( | void |  | ) |

JSON_EXPORT struct json_tokener* json_tokener_new_ex | ( | int | depth | ) |

JSON_EXPORT struct json_object* json_tokener_parse | ( | const char * | str | ) |

JSON_EXPORT struct json_object* json_tokener_parse_ex | ( | struct json_tokener * | tok,
|  | const char * | str,
|  | int | len
| ) |  |

Parse a string and return a non-NULL json_object if a valid JSON value is found. The string does not need to be a JSON object or array; it can also be a string, number or boolean value.

A partial JSON string can be parsed. If the parsing is incomplete, NULL will be returned and json_tokener_get_error() will return json_tokener_continue. json_tokener_parse_ex() can then be called with additional bytes in str to continue the parsing.

If json_tokener_parse_ex() returns NULL and the error is anything other than json_tokener_continue, a fatal error has occurred and parsing must be halted. Then, the tok object must not be reused until json_tokener_reset() is called.

When a valid JSON value is parsed, a non-NULL json_object will be returned. Also, json_tokener_get_error() will return json_tokener_success. Be sure to check the type with json_object_is_type() or json_object_get_type() before using the object.

XXX this shouldn't use internal fields: Trailing characters after the parsed value do not automatically cause an error. It is up to the caller to decide whether to treat this as an error or to handle the additional characters, perhaps by parsing another json value starting from that point.

Extra characters can be detected by comparing the tok->char_offset against the length of the last len parameter passed in.

The tokener does not maintain an internal buffer so the caller is responsible for calling json_tokener_parse_ex with an appropriate str parameter starting with the extra characters.

This interface is presently not 64-bit clean due to the int len argument so the function limits the maximum string size to INT32_MAX (2GB). If the function is called with len == -1 then strlen is called to check the string length is less than INT32_MAX (2GB)

Example:

json_object *jobj = NULL;
const char *mystring = NULL;
int stringlen = 0;
enum json_tokener_error jerr;
do {
mystring = ... // get JSON string, e.g. read from file, etc...
stringlen = strlen(mystring);
jobj = json_tokener_parse_ex(tok, mystring, stringlen);
} while ((jerr = json_tokener_get_error(tok)) == json_tokener_continue);
if (jerr != json_tokener_success)
{
fprintf(stderr, "Error: %s\n", json_tokener_error_desc(jerr));
// Handle errors, as appropriate for your application.
}
if (tok->char_offset < stringlen) // XXX shouldn't access internal fields
{
// Handle extra characters after parsed object as desired.
// e.g. issue an error, parse another object from that point, etc...
}
// Success, use jobj here.

Parameters

  tok | a json_tokener previously allocated with json_tokener_new()
  str | an string with any valid JSON expression, or portion of. This does not need to be null terminated.
  len | the length of str

JSON_EXPORT struct json_object* json_tokener_parse_verbose | ( | const char * | str,
|  | enum json_tokener_error * | error
| ) |  |

JSON_EXPORT void json_tokener_reset | ( | struct json_tokener * | tok | ) |

JSON_EXPORT void json_tokener_set_flags | ( | struct json_tokener * | tok,
|  | int | flags
| ) |  |

Set flags that control how parsing will be done.