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json_pointer.h
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json_pointer.h
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/*
* Copyright (c) 2016 Alexadru Ardelean.
*
* This is free software; you can redistribute it and/or modify
* it under the terms of the MIT license. See COPYING for details.
*
*/
#ifndef _json_pointer_h_
#define _json_pointer_h_
#include "json_object.h"
#ifdef __cplusplus
extern "C" {
#endif
/**
* Retrieves a JSON sub-object from inside another JSON object
* using the JSON pointer notation as defined in RFC 6901
* https://tools.ietf.org/html/rfc6901
*
* The returned JSON sub-object is equivalent to parsing manually the
* 'obj' JSON tree ; i.e. it's not a new object that is created, but rather
* a pointer inside the JSON tree.
*
* Internally, this is equivalent to doing a series of 'json_object_object_get()'
* and 'json_object_array_get_idx()' along the given 'path'.
*
* Note that the 'path' string supports 'printf()' type arguments, so, whatever
* is added after the 'res' param will be treated as an argument for 'path'
* Example: json_pointer_get(obj, "/foo/%d/%s", &res, 0, bar)
* This means, that you need to escape '%' with '%%' (just like in printf())
*
* @param obj the json_object instance/tree from where to retrieve sub-objects
* @param path a (RFC6901) string notation for the sub-object to retrieve
* @param res a pointer where to store a reference to the json_object
* associated with the given path
*
* @return negative if an error (or not found), or 0 if succeeded
*/
int json_pointer_get(struct json_object *obj, const char *path, struct json_object **res);
/**
* This is a variant of 'json_pointer_get()' that supports printf() style arguments.
*
* Example: json_pointer_getf(obj, res, "/foo/%d/%s", 0, bak)
* This also means that you need to escape '%' with '%%' (just like in printf())
*
* Please take into consideration all recommended 'printf()' format security
* aspects when using this function.
*
* @param obj the json_object instance/tree to which to add a sub-object
* @param res a pointer where to store a reference to the json_object
* associated with the given path
* @param path_fmt a printf() style format for the path
*
* @return negative if an error (or not found), or 0 if succeeded
*/
int json_pointer_getf(struct json_object *obj, struct json_object **res, const char *path_fmt, ...);
/**
* Sets JSON object 'value' in the 'obj' tree at the location specified
* by the 'path'. 'path' is JSON pointer notation as defined in RFC 6901
* https://tools.ietf.org/html/rfc6901
*
* Note that 'obj' is a double pointer, mostly for the "" (empty string)
* case, where the entire JSON object would be replaced by 'value'.
* In the case of the "" path, the object at '*obj' will have it's refcount
* decremented with 'json_object_put()' and the 'value' object will be assigned to it.
*
* For other cases (JSON sub-objects) ownership of 'value' will be transferred into
* '*obj' via 'json_object_object_add()' & 'json_object_array_put_idx()', so the
* only time the refcount should be decremented for 'value' is when the return value of
* 'json_pointer_set()' is negative (meaning the 'value' object did not get set into '*obj').
*
* That also implies that 'json_pointer_set()' does not do any refcount incrementing.
* (Just that single decrement that was mentioned above).
*
* Note that the 'path' string supports 'printf()' type arguments, so, whatever
* is added after the 'value' param will be treated as an argument for 'path'
* Example: json_pointer_set(obj, "/foo/%d/%s", value, 0, bak)
* This means, that you need to escape '%' with '%%' (just like in printf())
*
* @param obj the json_object instance/tree to which to add a sub-object
* @param path a (RFC6901) string notation for the sub-object to set in the tree
* @param value object to set at path
*
* @return negative if an error (or not found), or 0 if succeeded
*/
int json_pointer_set(struct json_object **obj, const char *path, struct json_object *value);
/**
* This is a variant of 'json_pointer_set()' that supports printf() style arguments.
*
* Example: json_pointer_setf(obj, value, "/foo/%d/%s", 0, bak)
* This also means that you need to escape '%' with '%%' (just like in printf())
*
* Please take into consideration all recommended 'printf()' format security
* aspects when using this function.
*
* @param obj the json_object instance/tree to which to add a sub-object
* @param value object to set at path
* @param path_fmt a printf() style format for the path
*
* @return negative if an error (or not found), or 0 if succeeded
*/
int json_pointer_setf(struct json_object **obj, struct json_object *value, const char *path_fmt, ...);
#ifdef __cplusplus
}
#endif
#endif