Matching specific characters individually except in specific expression

Question

Let's say I have a string:
cat_dog_ !mouse= <name="Jake_Russell!"> gog+cat

I want to match specific symbols _!=+, but not in <name="Jake_Russell!"> that part of this regex <name=\".+\">. So result should be __!=+

I've tried lookAhead:
(?!<name=\".+\">)([_!=+])
but as a result, it matches symbols in <name="Jack_Russell!"> too.

Is another way of expressing the requirement *match a list of special characters, except when they are between quotes*? — Bohemian, Apr 02 '23 at 03:09
@Bohemian the requirement is to match a list of special characters. But everywhere except this specific pattern expression: . Not just between quotes. Symbol `=` in ` — Iga, Apr 02 '23 at 03:33
Unrelated: The dog breed is [Jack Russel](https://en.wikipedia.org/wiki/Jack_Russell_Terrier), not Jake Russel — Bohemian, Apr 02 '23 at 03:46
I don't think you can do it because you'd need a variable length look behind, which are not supported. Would not matching within quotes and not matching after ` — Bohemian, Apr 02 '23 at 04:04
@Bohemian, related to unrelated: as shown at your link, the dog breed is Jack Russell Terrier. Note two "l"'s in "Russell" ¯\\_(ツ)_/¯ (great dogs). — Cary Swoveland, Apr 02 '23 at 21:57

score 3 · Accepted Answer · answered Apr 02 '23 at 09:09

3

I think you could try capturing groups, capture part <name=\".+\"> into 1 ignored group, and another group for matched specific symbols.

Regex patten: (?<ignored_group><name=".+">)|(?<matched_group>[_!=+])

See demo here

answered Apr 02 '23 at 09:09

Trung Duong

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Thanks! A named group is a suitable option in my case – Iga Apr 02 '23 at 22:43

The fourth bird · Answer 2 · 2023-04-02T09:22:01.087

You can rule out what you don't want, and then capture when you want using an alternation and a capture group:

<name="[^"]*">|([_!=+])

Explanation

<name= Match literally
"[^"]*" Negated character class, match from "..."
> Match literally
| Or
([_!=+]) Capture group 1, match any of the listed characters

Regex demo

If there can be more than name= and no more occurrences of < and > you might also use:

<[^<>]*\bname="[^"]*"[^<>]*>|([_!=+])

Regex demo

score 0 · Answer 3 · answered Apr 02 '23 at 06:33

Because variable length look behinds are not supported, you can't exclude matches that appear after particular text.

However, you can exclude a match immediately after <name and exclude matches within quotes, which is the best you can do given the limitations of regex:

(?<!<name)[_!=+](?=(([^"]*"){2})*[^"]*$)

See live demo.

Matching specific characters individually except in specific expression

3 Answers3