Regex capturing block of condition

Question

I have the following string

huile contains rgbgrbrb9gr && huile contains fcecec

I use this regex in order to capture a block of condition:

(.+) (contains) (.+)

It works with one block "huile contains rgbgrrb9gr" but if i add another condition with && or || operator, the two operators are captured. What i'm expecting to capture if the two blocks excluding && and || operator.

Can someone have any idea how to achieve this?

First output: huile contains rgbgrbrb9gr Second output: huile contains fcecec — Yanis600, Dec 24 '21 at 11:00
**Side note**: regex is only suitable for matching lexical tokens. If you have a context-free grammar that you need to parse, you need to look for tools such as yacc or bison. — DannyNiu, Dec 24 '21 at 11:10
Additionally you might want to indicate which dialect of regex you're using. JavaScript RegExp? Perl-compatible? POSIX? — DannyNiu, Dec 24 '21 at 11:52
@Yanis600 Do you want to prevent matching `&&` and `||` or do you not want to match a `&` char and a `|` char? Can you add to your question an example what should match and what should not match? Do you want 3 capture groups in the result, or only matches? — The fourth bird, Dec 24 '21 at 12:33
I have the following filter string as an example: 'oil & blah'blah' contains 'oil&blah'blah' && 'oil & blah'blah' contains 'oil blah's' What i want to catch is the following patterns 'string' contains 'substring' the ' && ' or ' || ' must be excluded, and the pattern mentionned above has three matches The & and | must only be captured in string i want to search and the string where to search — Yanis600, Dec 24 '21 at 12:42
@Yanis600 Perhaps like this? https://regex101.com/r/taFZUP/1 — The fourth bird, Dec 24 '21 at 13:17
Wonderful, thank you so much :) I assume that regex are really hard to built. — Yanis600, Dec 24 '21 at 13:32

DannyNiu · Accepted Answer · 2021-12-24T11:38:12.313

Regex normally matches the longest input it finds.

You need to exclude & and | from your input, like this:

([^&|]+) (contains) ([^&|]+)

If you instead desire to exclude double-character && and ||, I suggest spliting your string based on those delimiters first, then matching using regex, as complex parsing is really beyond the realm of regex (they're grammars actually).

But, a regex solution is nontheless possible

The rough idea is that, you want to match a string with

an optional prefix consisting of no & or |
a single & or | followed by a non-empting string
repeating 2 for non-zero number of times.

the subpattern would be something like this:

(([^&|]+)?([&|][^&|]+)+)

additionally, you'll want something like the egrep's x flag, to match the entire string, otherwise it'll be possible that an empty string turns up.

The full regex would look something like this (capture groups're re-numbered)

(([^&|]+)?([&|][^&|]+)+) (contains) (([^&|]+)?([&|][^&|]+)+)

it works but if i need to search for & or | operator, i got a wrong capture. What i need to capture is for example: 'oil & other' contains 'oil &' — Yanis600, Dec 24 '21 at 11:13

Jean Will · Answer 2 · 2021-12-24T14:15:21.947

1

After reading the post comments, the desired result was more clear.

This one could work too:

(?<=^|(?:&&|\|\|) )(.+?) (contains) (.+?)(?= (?:&&|\|\|)|$)

https://regex101.com/r/YDFpN9/2

edited Dec 24 '21 at 14:15

answered Dec 24 '21 at 11:10

Jean Will

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score 1 · Answer 3 · answered Dec 24 '21 at 16:07

If you want 3 capture groups, you could match what you don't want first, and then capture in groups what you want to keep making use of a tempered greedy token approach to not cross matching && or || or the word contains.

\|{2,}|&{2,}|((?:(?!&&|\|\||\bcontains\b).)*) (contains) ((?:(?!&&|\|\||\bcontains\b).)*)

The pattern matches:

\|{2,}|&{2,} Match either 2 or more pipe chars or ampersands (what you don't want to keep)
| Or
( Capture group 1
- (?:(?!&&|\|\||\bcontains\b).)* Match any char except a newline if what is directly to the right is not && || or contains
) Close group 1
(contains) Match the word contains in group 2 between spaces
( Capture group 3
- (?:(?!&&|\|\||\bcontains\b).)* Same approach as above
) Close group 3

Regex demo

Regex capturing block of condition

3 Answers3