tsoding.frozen/docs/api/json_walk.md

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title: json_walk()

/* Callback-based API */
typedef void (*json_walk_callback_t)(void *callback_data, const char *path,
                                     const struct json_token *token);

/*
 * Parse `json_string`, invoking `callback` function for each JSON token.
 * Return number of bytes processed
 */
int json_walk(const char *json_string, int json_string_length,
              json_walk_callback_t callback, void *callback_data);

json_walk() is a low-level, callback based parsing API. json_walk() calls given callback function for each scanned value.

Callback receives a path to the value, a JSON token that points to the value, and arbitrary user data pointer.

The path is constructed using this rule:

• Root element has "" (empty string) path
• When an object starts, . (dot) is appended to the path
• When an object key is parsed, a key name is appended to the path
• When an array is parsed, for each element an [ELEMENT_INDEX] is appended

For example, consider the following json string: { "foo": 123, "bar": [ 1, 2, { "baz": true } ] }. The sequence of callback invocations will be as follows:

• path: .foo, token: 123
• path: .bar[0], token: 1
• path: .bar[1], token: 2
• path: .bar[2].baz, token: true
• path: .bar[2], token: { "baz": true }
• path: .bar, token: [ 1, 2, { "baz": true } ]
• path: (empty string), token: { "foo": 123, "bar": [ 1, 2, { "baz": true } ] }

If top-level element is an array: [1, {"foo": 2}]

• path: [0], token: 1
• path: [1].foo, token: 2
• path: [1], token: {"foo": 2}
• path: (empty string), token: [1, {"foo": 2}]

If top-level element is an scalar: true

• path: (empty string), token: true