On 2023-08-24  10:52, Jens Schmidt wrote:
> On 2023-08-24  09:32, Ihor Radchenko wrote:

>> I prefer (B). And we will need to allow escaping of the "\" itself. Like
>> \\.
> 
> OK.  Since backslash is not used yet in the rest of the regexp, (B)
> should be rather edge-case-free.  So the corresponding subre to match
> property names would look like
> 
>   \(?5:\(?:[[:alnum:]]+\|\\[^[:space:]]\)+\)
> 
> IOW, backslash quotes everything except whitespace, which by definition
> cannot be part of a property name.
> 
> Will start on this, but with tests and documentation this might take
> some time.

Here comes a first patch ... please check.