Should Regenerate use more single-character escape sequences? about regenerate HOT 8 CLOSED

For ranges, numerical values make more sense. But for individual characters that have an ASCII representation, it is much more readable to have them there.

from regenerate.

What printable ASCII characters do not need any escaping in JavaScript regular expression literals?

Here are all printable ASCII characters:

 !"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~

AFAIK, the following characters have to be escaped (prefixed with \) in JavaScript regular expressions:

$
(
)
*
+
.
?
[
\
^
{
|

That leaves the following list:

 !"#%&',-/0123456789:;<=>@ABCDEFGHIJKLMNOPQRSTUVWXYZ]_`abcdefghijklmnopqrstuvwxyz}~

Regenerate might return a character class that is wrapped in [], and even if it doesn’t, the output may be used in such a context, so - and ] must be escaped too. That leaves the following list of printable ASCII characters that do not need escaping:

 !"#%&',/0123456789:;<=>@ABCDEFGHIJKLMNOPQRSTUVWXYZ_`abcdefghijklmnopqrstuvwxyz}~

Are there any others in the above list that absolutely need escaping? @jdalton and @kitcambridge, I seem to recall you were aware of issues when not escaping ] etc. in certain (old) engines. Do you remember the details?

(Note that in Regenerate, non-ASCII symbols are escaped anyway (by design – Regenerate’s output should always be ASCII-only).)

from regenerate.

Ya I had to escape a few more for better narwhal/ringo support. See lodash/lodash@06d3740 (edge lodash).

}
]

from regenerate.

Ok so the final list of printable ASCII characters to escape is:

$()*+-.?[\]^{|}

And the list of printable ASCII characters that do not need escaping are:

 !"#%&',/0123456789:;<=>@ABCDEFGHIJKLMNOPQRSTUVWXYZ_`abcdefghijklmnopqrstuvwxyz~

Thanks!

from regenerate.

Escaping / is required for some ancient version of Firefox (totally may not be relevant).

from regenerate.

Ooh – any ideas which exact version(s), or where I can find more info?

from regenerate.

You're gonna laugh at me, but it's Firefox v1 (I have a note in platform.js source)

from regenerate.

jaw drops

from regenerate.