Subject: bug#24784: 26.0.50; JSON strings with utf-16 escape codes

From: Philipp Stephani <[email-masked]>
Date: Sat, 31 Dec 2016 16:53:27 +0000

Dmitry Gutov <[email-masked]> schrieb am Di., 25. Okt. 2016 um 01:19 Uhr:

> Philipp,
>
> Thanks. Some comments:
>
> On 24.10.2016 22:57, Philipp Stephani wrote:
>
> > +(defsubst json--decode-utf-16-surrogates (high low)
>
> IIRC, there might be no actual benefit from making it a defsubst. If
> someone could benchmark it, I'd like to see the result.
>

Agreed; converted to defun. I've only used defsubst because some other
helper functions also used defsubst.

>
> > +     ;; Special-case UTF-16 surrogate pairs,
> > +     ;; cf. https://tools.ietf.org/html/rfc7159#section-7
> > +     ((looking-at
> > +       (rx (group (any "Dd") (any "89ABab") (= 2 (any "0-9A-Fa-f")))
> > +           "\\u" (group (any "Dd") (any "C-Fc-f") (= 2 (any
> "0-9A-Fa-f")))))
> > +      (json-advance 10)
> > +      (json--decode-utf-16-surrogates
> > +       (string-to-number (match-string 1) 16)
> > +       (string-to-number (match-string 2) 16)))
>
> Shouldn't this go below the UTF-8 case, as the less-frequent one?
>

No, the below case is more general and therefore has to come last.

>
> >  (ert-deftest test-json-encode-string ()
> >    (should (equal (json-encode-string "foo") "\"foo\""))
> >    (should (equal (json-encode-string "a\n\fb") "\"a\\n\\fb\""))
> > -  (should (equal (json-encode-string "\nasdÑ„Ñ‹Ð²\u001f\u007ffgh\t")
> > -                 "\"\\nasdÑ„Ñ‹Ð²\\u001f\u007ffgh\\t\"")))
> > +  (should (equal (json-encode-string "\nasdÑ„Ñ‹Ð²ð „ž\u001f\u007ffgh\t")
> > +                 "\"\\nasdÑ„Ñ‹Ð²ð „ž\\u001f\u007ffgh\\t\"")))
>
> Why are we testing string encoding here?
>

It's not 100% related to the patch, but I think it can be included for
symmetry reasons (testing encoding as well as decoding).