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/*
* $Id: json_tokener.h,v 1.10 2006/07/25 03:24:50 mclark Exp $
*
* Copyright (c) 2004, 2005 Metaparadigm Pte. Ltd.
* Michael Clark <michael@metaparadigm.com>
*
* This library is free software; you can redistribute it and/or modify
* it under the terms of the MIT license. See COPYING for details.
*
*/
/**
* @file
* @brief Methods to parse an input string into a tree of json_object objects.
*/
#ifndef _json_tokener_h_
#define _json_tokener_h_
#include "json_object.h"
#include <stddef.h>
#ifdef __cplusplus
extern "C" {
#endif
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_parse_utf8_string,
json_tokener_error_memory,
json_tokener_error_size
};
/**
* @deprecated Don't use this outside of json_tokener.c, it will be made private in a future release.
*/
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_escape_unicode_need_escape,
json_tokener_state_escape_unicode_need_u,
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
};
/**
* @deprecated Don't use this outside of json_tokener.c, it will be made private in a future release.
*/
struct json_tokener_srec
{
enum json_tokener_state state, saved_state;
struct json_object *obj;
struct json_object *current;
char *obj_field_name;
};
#define JSON_TOKENER_DEFAULT_DEPTH 32
/**
* Internal state of the json parser.
* Do not access any fields of this structure directly.
* Its definition is published due to historical limitations
* in the json tokener API, and will be changed to be an opaque
* type in the future.
*/
struct json_tokener
{
/**
* @deprecated Do not access any of these fields outside of json_tokener.c
*/
char *str;
struct printbuf *pb;
int max_depth, depth, is_double, st_pos;
/**
* @deprecated See json_tokener_get_parse_end() instead.
*/
int char_offset;
/**
* @deprecated See json_tokener_get_error() instead.
*/
enum json_tokener_error err;
unsigned int ucs_char, high_surrogate;
char quote_char;
struct json_tokener_srec *stack;
int flags;
};
/**
* Return the offset of the byte after the last byte parsed
* relative to the start of the most recent string passed in
* to json_tokener_parse_ex(). i.e. this is where parsing
* would start again if the input contains another JSON object
* after the currently parsed one.
*
* Note that when multiple parse calls are issued, this is *not* the
* total number of characters parsed.
*
* In the past this would have been accessed as tok->char_offset.
*
* See json_tokener_parse_ex() for an example of how to use this.
*/
JSON_EXPORT size_t json_tokener_get_parse_end(struct json_tokener *tok);
/**
* @deprecated Unused in json-c code
*/
typedef struct json_tokener json_tokener;
/**
* 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.
*
* Note that setting this will also effectively disable parsing
* of multiple json objects in a single character stream
* (e.g. {"foo":123}{"bar":234}); if you want to allow that
* also set JSON_TOKENER_ALLOW_TRAILING_CHARS
*
* This flag is not set by default.
*
* @see json_tokener_set_flags()
*/
#define JSON_TOKENER_STRICT 0x01
/**
* Use with JSON_TOKENER_STRICT to allow trailing characters after the
* first parsed object.
*
* @see json_tokener_set_flags()
*/
#define JSON_TOKENER_ALLOW_TRAILING_CHARS 0x02
/**
* Cause json_tokener_parse_ex() to validate that input is UTF8.
* If this flag is specified and validation fails, then
* json_tokener_get_error(tok) will return
* json_tokener_error_parse_utf8_string
*
* This flag is not set by default.
*
* @see json_tokener_set_flags()
*/
#define JSON_TOKENER_VALIDATE_UTF8 0x10
/**
* Given an error previously returned by json_tokener_get_error(),
* return a human readable description of the error.
*
* @return a generic error message is returned if an invalid error value is provided.
*/
JSON_EXPORT const char *json_tokener_error_desc(enum json_tokener_error jerr);
/**
* 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 json_tokener_error_desc().
*/
JSON_EXPORT enum json_tokener_error json_tokener_get_error(struct json_tokener *tok);
/**
* Allocate a new json_tokener.
* When done using that to parse objects, free it with json_tokener_free().
* See json_tokener_parse_ex() for usage details.
*/
JSON_EXPORT struct json_tokener *json_tokener_new(void);
/**
* Allocate a new json_tokener with a custom max nesting depth.
* @see JSON_TOKENER_DEFAULT_DEPTH
*/
JSON_EXPORT struct json_tokener *json_tokener_new_ex(int depth);
/**
* Free a json_tokener previously allocated with json_tokener_new().
*/
JSON_EXPORT void json_tokener_free(struct json_tokener *tok);
/**
* Reset the state of a json_tokener, to prepare to parse a
* brand new JSON object.
*/
JSON_EXPORT void json_tokener_reset(struct json_tokener *tok);
/**
* Parse a json_object out of the string `str`.
*
* If you need more control over how the parsing occurs,
* see json_tokener_parse_ex().
*/
JSON_EXPORT struct json_object *json_tokener_parse(const char *str);
/**
* Parser a json_object out of the string `str`, but if it fails
* return the error in `*error`.
* @see json_tokener_parse()
* @see json_tokener_parse_ex()
*/
JSON_EXPORT struct json_object *json_tokener_parse_verbose(const char *str,
enum json_tokener_error *error);
/**
* Set flags that control how parsing will be done.
*/
JSON_EXPORT void json_tokener_set_flags(struct json_tokener *tok, int flags);
/**
* 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, with a reference count of one which belongs to the caller. 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.
*
* 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.
*
* If the caller knows that they are at the end of their input, the length
* passed MUST include the final '\0' character, so values with no inherent
* end (i.e. numbers) can be properly parsed, rather than just returning
* json_tokener_continue.
*
* Extra characters can be detected by comparing the value returned by
* json_tokener_get_parse_end() against
* the length of the last len parameter passed in.
*
* The tokener does \b not maintain an internal buffer so the caller is
* responsible for a subsequent call to 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:
* @code
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);
if (end_of_input)
stringlen++; // Include the '\0' if we know we're at the end of input
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 (json_tokener_get_parse_end(tok) < stringlen)
{
// Handle extra characters after parsed object as desired.
// e.g. issue an error, parse another object from that point, etc...
}
// Success, use jobj here.
@endcode
*
* @param tok a json_tokener previously allocated with json_tokener_new()
* @param str an string with any valid JSON expression, or portion of. This does not need to be null terminated.
* @param len the length of str
*/
JSON_EXPORT struct json_object *json_tokener_parse_ex(struct json_tokener *tok, const char *str,
int len);
#ifdef __cplusplus
}
#endif
#endif