(text json pointer) - JSON Pointer

This library provides JSON Pointer procedures.

The specification of JSON Pointer is defined by the RFC 6901.

The following example shows simple usage of the library:

This is an input file named example.json.

{
  "id": 1234,
  "data": {
    "datum0": [0, 1, 2],
    "datum1": [3, 4]
  }
}

(import (rnrs) (rfc json-pointer) (text json))

(define id-pointer (json-pointer "/id"))

(let ((json (call-with-input-file "example.json" json-read))) (id-pointer json)) ```

1234

(import (rnrs) (rfc json-pointer) (text json))

(define data-pointer (json-pointer "/data"))

#|
example.json
|#
(let ((json (call-with-input-file "example.json" json-read)))
  ;; Retrievs /data/datum0
  ((json-pointer "/datum0" data-pointer) json))

Returns a procedure takes one which must be a list or vector representing JSON object. The given poinster must be a string or textual input port which start with /.

The optional argument parent is passed, then it must be a procedure returned by the json-pointer and is called before the current pointer is processed.

0.9.12 The returning procedure is called with second argument, then it will be the default value of not-found. This is useful when you are writing something below:

(define (wrap p)
  (lambda (json default)
    (let ((r (p json)))
      (if (json-pointer-not-found? r)
          default
          r))))
(define pointer (wrap (json-pointer "/foo")))
(pointer json #f)

The above can simply be like this:

(define pointer (json-pointer "/foo"))
(pointer json #f)