Word/punctuation string modifiers complicates parsing syntax that is sensitive to newlines about peg.jl HOT 6 CLOSED

Thanks for your interest in PEG.jl, and sorry for my delay in replying (I was on vacation, and then working through the backlog from that vacation).

I had thought about doing something like this, but I was kind of on the fence because I wanted to keep it simple. But I think seeing that someone else wants this feature too has pushed me off the fence.

I think it might be good to have one extra modifier that changes the behavior of p and w, rather than two modifiers that copy p and w with the change. Modifier letters are a scarce resource, and in addition to overriding Julia's imsx, I'd like to avoid redefining those that are in active use in other languages like Perl. That leaves bfhjkqtvyz. How about h for horizontal?

I think most whitespace characters are horizontal, so I should just list the ones that aren't, in a negative lookahead before the \s. That would turn the implementation of p from \s* to (?:(?![\r\n\v\f\u85])\s)*. That is to say, the vertical whitespace characters are: carriage return, line feed, vertical tab, form feed, and next line. Did I miss any?

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Thanks for your reply! There is actually a special horizontal whitespace \h regex form, so we can probably use that directly, right?

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So would this then be?

1. r","p to match comma, followed by any whitespace
2. r","ph to match comma, followed by any horizontal whitespace
3. r"BEGIN"w to match "BEGIN", followed by any whitespace
4. r"BEGIN"wh to match "BEGIN", followed by any horizontal whitespace

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Oh, \h is good to know! Apparently it was added in Perl 5.10, after I learned Perl 5.6 :)

And yes, your four examples are correct.

OK, I just committed this change; eventually this will be version 0.2.0, once the CI tests finish and I submit the version tag/metadata.

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Hm, mac tests are taking forever to even start running. Submitted it anyway; hopefully it'll get there eventually.

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They seem to have passed eventually. Thanks @wdebeaum, this is super helpful!

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