JSON parser

Kore provides a built-in JSON parser for your applications.

Index

Examples

See the included example in the Kore source tree for an example on how to use this API.

kore_json_init

Synopsis

void kore_json_init(struct kore_json *json, const u_int8_t *data, size_t len);

Description

Initializes a kore_json context. This must be called before any other function can be safely used.

Parameter Description
json A kore_json data structure.
data The JSON data to be parsed.
len The length of the JSON data to be parsed.

Returns

Nothing

kore_json_cleanup

Synopsis

void kore_json_cleanup(struct kore_json *json);

Description

Cleanup the kore_json context and release all associated resources. This must be called when you no longer need the context.

Parameter Description
json A kore_json data structure.

Returns

Nothing

kore_json_parse

Synopsis

int kore_json_parse(struct kore_json *json);

Description

Parse the JSON data that was set via kore_json_init.

Parameter Description
json A kore_json data structure.

Returns

Returns KORE_RESULT_OK if parsing was successful or KORE_RESULT_ERROR if the parsing failed. If the parsing failed the json->error field holds the error code.

This error code can be translated to a human readable string via the kore_json_strerror() function.

kore_json_find_object

Synopsis

struct kore_json_item *kore_json_find_object(struct kore_json_item *item, const char *name);

Description

Find an object named name in the JSON root item.

Parameter Description
item A kore_json_item data structure representing the root.
name The name of the object to be found.

Returns

A pointer to the JSON object as a kore_json_item data structure or NULL if the object was not found.

struct kore_json_item        *object, *item;

if ((object = kore_json_find_object(json.root, "person")) == NULL)
    return;

TAILQ_FOREACH(item, &object->data.items, list) {
    printf("got a entry in the object of type %d\n", item->type);
}

kore_json_find_array

Synopsis

struct kore_json_item *kore_json_find_array(struct kore_json_item *item, const char *name);

Description

Find an array named name in the JSON root item.

Parameter Description
item A kore_json_item data structure representing the root.
name The name of the array to be found.

Returns

A pointer to the JSON array as a kore_json_item data structure or NULL if the array was not found.

struct kore_json_item        *items, *item;

if ((items = kore_json_find_array(json.root, "items")) == NULL)
    return;

TAILQ_FOREACH(item, &items->data.items, list) {
    printf("got a entry in the array of type %d\n", item->type);
}

kore_json_find_string

Synopsis

struct kore_json_item *kore_json_find_string(struct kore_json_item *item, const char *name);

Description

Find a string named name in the JSON root item.

Parameter Description
item A kore_json_item data structure representing the root.
name The name of the string to be found.

Returns

A pointer to the JSON string as a kore_json_item data structure or NULL if the string was not found.

Example

struct kore_json_item        *name;

name = kore_json_find_string(json.root, "name");
if (name != NULL)
    printf("found name '%s'\n", name->data.string);

kore_json_find_number

Synopsis

struct kore_json_item *kore_json_find_number(struct kore_json_item *item, const char *name);

Description

Find a number named name in the JSON root item.

Parameter Description
item A kore_json_item data structure representing the root.
name The name of the number to be found.

Returns

A pointer to the JSON number as a kore_json_item data structure or NULL if the number was not found.

Example

struct kore_json_item        *price;

price = kore_json_find_number(json.root, "price");
if (price != NULL)
    printf("found 'price' with value of %.0f\n", price->data.number);

kore_json_find_literal

Synopsis

struct kore_json_item *kore_json_find_literal(struct kore_json_item *item, const char *name);

Description

Find a literal named name in the JSON root item.

Parameter Description
item A kore_json_item data structure representing the root.
name The name of the literal to be found.

Returns

A pointer to the JSON literal as a kore_json_item data structure or NULL if the literal was not found.

Possible values

KORE_JSON_TRUE - The JSON true value KORE_JSON_FALSE - The JSON false value KORE_JSON_NULL - The JSON null value

Example

struct kore_json_item        *istrue;

istrue = kore_json_find_literal(json.root, "istrue");
if (istrue != NULL && istrue->data.literal == KORE_JSON_TRUE)
    printf("istrue is set to true\n");

kore_json_create_object

Synopsis

struct kore_json_item *kore_json_create_object(struct kore_json_item *parent, const char *name);

Description

Creates a new JSON object under the given parent with the given name.

Parameter Description
parent A kore_json_item data structure representing the parent.
name The name of the object to be created.

Parent

The parent parameter can be NULL if no parent is to be used.

Returns

A pointer to the JSON object as a kore_json_item data structure or NULL if something has failed.

Example

struct kore_json_item        *person;

if ((person = kore_json_create_object(NULL, "person")) == NULL)
    /* handle */

if (kore_json_create_number(person, "age", 34) == NULL)
    /* handle */

kore_json_create_array

Synopsis

struct kore_json_item *kore_json_create_array(struct kore_json_item *parent, const char *name);

Description

Creates a new JSON array under the given parent with the given name.

Parameter Description
parent A kore_json_item data structure representing the parent.
name The name of the array to be created.

Parent

The parent parameter can be NULL if no parent is to be used.

Returns

A pointer to the JSON array as a kore_json_item data structure or NULL if something has failed.

Example

struct kore_json_item        *array;

if ((array = kore_json_create_array(NULL, "person")) == NULL)
    /* handle */

if (kore_json_create_number(array, NULL, 34) == NULL)
    /* handle */

if (kore_json_create_number(array, NULL, 27) == NULL)
    /* handle */

kore_json_create_string

Synopsis

struct kore_json_item *kore_json_create_string(struct kore_json_item *parent, const char *name, const char *value);

Description

Creates a new JSON string under the given parent with the given name.

Parameter Description
parent A kore_json_item data structure representing the parent.
name The name of the string to be created.
value The value of the string.

Parent

The parent parameter can be NULL if no parent is to be used.

Returns

A pointer to the JSON string as a kore_json_item data structure or NULL if something has failed.

Example

if (kore_json_create_string(parent, "person", "hacker") == NULL)
    /* handle */

kore_json_create_number

Synopsis

struct kore_json_item *kore_json_create_number(struct kore_json_item *parent, const char *name, double value);

Description

Creates a new JSON number under the given parent with the given name.

Parameter Description
parent A kore_json_item data structure representing the parent.
name The name of the number to be created.
value The value of the number as a C double.

Parent

The parent parameter can be NULL if no parent is to be used.

Returns

A pointer to the JSON number as a kore_json_item data structure or NULL if something has failed.

Example

if (kore_json_create_number(parent, "age", 34) == NULL)
    /* handle */

kore_json_create_literal

Synopsis

struct kore_json_item *kore_json_create_literal(struct kore_json_item *parent, const char *name, int value);

Description

Creates a new JSON literal under the given parent with the given name.

Parameter Description
parent A kore_json_item data structure representing the parent.
name The name of the literal to be created.
value The value of the literal (see below).

Parent

The parent parameter can be NULL if no parent is to be used.

Possible values

KORE_JSON_TRUE - The JSON true value KORE_JSON_FALSE - The JSON false value KORE_JSON_NULL - The JSON null value

Returns

A pointer to the JSON literal as a kore_json_item data structure or NULL if something has failed.

Example

if (kore_json_create_literal(parent, "istrue", KORE_JSON_FALSE) == NULL)
    /* handle */

kore_json_strerror

Synopsis

const char *kore_json_strerror(struct kore_json *json);

Description

Returns a human readable string for the error that occurred in the context.

Parameter Description
json A kore_json context in which an error occurred.

Returns

A pointer to a human readable string that describes the error. This pointer should not be freed by the caller.

Example

kore_log(LOG_INFO, "parsing error '%s'", kore_json_strerror(&json));

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