Regex: match, but not if in a comment

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I have a file of data fields, which may contain comments, like below:

id, data, data, data
101 a, b, c
102 d, e, f
103 g, h, i // has to do with 101 a, b, c
104 j, k, l
//105 m, n, o
// 106 p, q, r

As you can see in the first comment above, there are direct references to a matching pattern. Now, I want to capture 103 and it's three data fields, but I don't want to capture what's in the comments.

I've tried negative lookbehind to exclude 105 and 106, but I can't come up with a regex to capture both.

(?<!//)(\b\d+\b),\s(data),\s(data),\s(data)

This will capture all but exclude capture of 105, but to specify

(?<!//\s*) or (?<!//.*)

as my attempt to exclude a comment with any whitespace or any characters invalidates my entire regex.

I have a feeling I need a crafty use of an anchor, or I need to wrap what I want in a capture group and make a reference to it (like with $1) in my lookbehind.


If this is another case of "regular expressions don't support recursion" because it's a regular language (a la automata theory), please point that out.

Is it possible to exclude the comments in 103, and lines 105 and 106, using a regular expression? If so, how?

4 Answers

One another way I have just used in the text editor with the regex when you don't have the regex look ahead/behind features is just use a sequence of these:

^[^\r\n/]*(/[^/])?[^\r\n/]*(/[^/])?my_search_sequence

It will ignore sequence of / splitted by not / character by maximum of 2 of them. If you want more, then just add more:

^[^\r\n/]*(/[^/])?[^\r\n/]*(/[^/])?[^\r\n/]*(/[^/])my_search_sequence

and so on.

Probability that your search word would be behind the sequence like these does reduce with the length of the regex.

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