Doesn't rg support RegEx flags such as Ungreedy matching?

[StacktraceException]

It seems that a lazy positive lookahead is impossible, also it seems that there is no such (I guess redundant) thing, because the Ungreedy flag (make all matches lazy by default) accomplishes the task.

You can see for yourself with this PCRE implementation: regex101.com

rg -Pe '^\d\d?\d?\.\d\d?M.*(?=\.)'

for this input:

2.5M	./kopia-kolejna/recup_dir.17/b10482719.jpg
4.2M	./kopia-kolejna/recup_dir.18/b14523847.jpg
6.7M	./kopia-kolejna/recup_dir.18/b11322221.tif

matches upto the last dot.

Adding a question mark to the syntax:

rg -Pe '^\d\d?\d?\.\d\d?M.*(?=\.?)'

makes it match all the input.

The same happens on that implementation website. BUT enabling the U flag makes rg -Pe '^\d\d?\d?\.\d\d?M.*(?=\.?)' work as wanted.

[BurntSushi]

Sorry I'm confused. What question are you asking here?

Non-greedy matching is unrelated and orthogonal to look around.

[StacktraceException]

Sorry but is this some Troll Post? The examples show everything including how they are related to look-around. What exactly are you confused about? sob., 3 paź 2020 o 18:17 Andrew Gallant <notifications@github.com> napisał(a):

…

Sorry I'm confused. What question are you asking here? Non-greedy matching is unrelated and orthogonal to look around. — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#1698 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AOSWAAA375JUR4ZYSYA4IUTSI5FCBANCNFSM4SCXGHMA> .

[BurntSushi]

If you accuse me of trolling you on my own issue tracker again, then you won't be welcome here. I'm trying to help. I simply do not understand what question you're asking or what problem you're trying to solve.

[BurntSushi]

Maybe all you're asking is how to use non-greedy matching. If so, I'll answer that, but your post is really confusing.

If you want to use non-greedy matching, then you have two options. The first is to add a question mark to the repetition operator that you want to be non-greedy. e.g., ??, +? and *? are the non-greedy versions of ?, + and *. You can also use the U flag to invert the greediness of all repetition operators.

As far as I know, this is standard across all regex engines that support greediness.

[BurntSushi]

PCRE2's Ungreedy flag (which is different than just adding a question mark to the syntax)

How is it different? Could you show an example, perhaps, using pcre2regex? (Or did you mean to reference pcre2grep before?)

[okdana]

please just tell how to use the PCRE2's Ungreedy flag in ripgrep

Are you talking about (?U)? As in, (?U)\w+ is equivalent to \w+??

[StacktraceException]

Sorry, I'm giving up on explaining anymore. Please just tell me how to use the PCRE2's Ungreedy flag in ripgrep.

[BurntSushi]

I legitimately don't know what you're talking about if the "ungreedy flag" isn't the same as .*?. The question mark makes the repetition ungreedy. That is its definition. As @okdana said, (?U:.*) is equivalent to .*?.

I mean, if I understood your question I would answer it. I'm not trying to be coy here.

[StacktraceException]

please just tell how to use the PCRE2's Ungreedy flag in ripgrep

Are you talking about (?U)? As in, (?U)\w+ is equivalent to \w+??

This is most probably what I had in mind. (it almost certainly is, I'd just need to test it out with what I have had tried to do when asking this question). Thank You.