Re: Syntax: allow newline but not blank lines in a region

Den lör 23 nov. 2024 04:59Doug Kearns <[email protected]> skrev:

> On Sat, 23 Nov 2024 at 04:28, BPJ <[email protected]> wrote:
>
>> I have a syntax for a markup language where certain delimited constructs
>> allow single newlines but not blank lines, i.e. this is OK
>>
>> ``` markup
>> {_foo
>> bar_}
>> ```
>>
>> but this is not OK
>>
>> ``` markup
>> {_foo
>>
>> bar_}
>> ```
>>
>> is there any way to set up a region so that it behaves like this? I tried
>> `oneline` plus a contained `syn match` which matches a newline not preceded
>> or followed by a blank line but no luck!
>>
>> I get the behavior I want with a `syn match` with this pattern
>>
>> ``` pattern
>> {_\%([^\n]\|\%(\_^\s*\)\@<!\n\%(\s*\_$\)\@!\)\{-}_}
>> ```
>>
>
> Does something like this work?
>
> :syn region foobar start="{_" end="_}" end="$" skip="\n\s*\S"
>


I already tried that. No lunch unfortunately. I'm going with the `syn
match` version which incorporates the single newline pattern. It is
probably less efficient but is also probably my only choice now as I found
that I also need to exclude backslash from the "normal" subpattern and skip
past backslash + char lest the closing delimiter is directly preceded by a
backslash.

BTW for reference the correct pattern, maybe inefficient but accurate, for
a newline not preceded or followed by any blank line is

``````pattern
\%(\_^\s*\)\@<!\n\%(\s*\_$\)@!
``````

i.e. with negative lookbehind for optional horizontal whitespace and a
start-of-line and the opposite negative lookahead for optional horizontal
whitespace and an end-of-line.

FWIW the backslash escape pattern I used is `\\\_.`, with later Special
highlighting of backslashes followed by ASCII punctuation or
space/newline/return. Who said it has to be easy! :-)


>
>> but then highlighting obviosly doesn't kick in until I type the closing
>> delimiter so I would prefer a region.
>>
>> Also is there a better way to match the start or end of the file than
>> `\_.\@<!` and `\_.\@!`?
>>
>
> :help \%^
>

Thanks. I still learn new things about Vim after having used it for ~20
years, which is both gratifying and frustrating!

/bpj



> Regards,
> Doug
>
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