Regular expression with an exception

Question

Is there any way to add a regex exception to a regular expression?

Example:

(regular expression/regular expression to ignore)

I have the following regular expression:

\W

But would like for it to ignore strings inside quotation marks (Regex i will use for this is: "(.*?)"). But i don't know how to add an exception to the \W regex.

I want something like this:

\W(ignore->"(.*?)")

Any ideas? Any help will be appreciated.

Yes, in PCRE, it is a piece of cake: `"[^"]*"(*SKIP)(*F)|\W`. What is your regex flavor? — Wiktor Stribiżew, Feb 12 '21 at 19:14
Ok, so what is your code? What is your intention: extract, replace, remove, split? Show some real life test case. — Wiktor Stribiżew, Feb 12 '21 at 19:15
I was trying to separate an input code (Java class in the form of a .txt) into an array of "tokens". I used the \W to separate the code into multiple lines. But with this i ran to the issue of having strings being split as well. Using an exception in the \W for strings inside quotes would fix this. :) — Carlos Daniel, Feb 12 '21 at 19:18
Please just find the dedicated language parser. A single splitting regex won't help you parse an arbitrary Java file correctly. — Wiktor Stribiżew, Feb 12 '21 at 19:20
This [thread](https://stackoverflow.com/questions/6511556/javascript-parser-for-java) should help, I hope. — Wiktor Stribiżew, Mar 05 '21 at 14:44

score 0 · Accepted Answer · edited Feb 12 '21 at 19:31

0

Edit: Your question asks about \W (non-word characters), but perhaps you meant to split on those. It seems you meant to match those, so I changed the upper-case \W to lower case \w in my answer.

You might be looking for something like this: (?:"[^"]*?"|\w)+

The idea is to treat quoted substrings differently. Here is how it works:

One or more of the contents: (?: "[^"]*?"|\w )+ where the contents are...
Either a quoted string [^"]*?" or word character \w
The quoted string is [^"]*?" is a " followed by as few as possible non-quote characters [^"]*?, followed by the closing ".

edited Feb 12 '21 at 19:31

Dharman

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answered Feb 12 '21 at 19:25

agent-j

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This `(?:"[^"]*?"|\w)+` is not going to help in the end, since a mere `String str = "with \"quotes\" inside";` line will break it. – Wiktor Stribiżew Feb 12 '21 at 20:27
Yes, this example only works for simple strings. If your source file includes things like `$"{("h")}"` or `@">""<"` it would likely need a language parser instead of regex. – agent-j Feb 15 '21 at 18:54

score 0 · Answer 2 · answered Feb 12 '21 at 23:37

I don't know how to do this using a single regex, but you can do it in 2 steps. (i) Replace the exception with an empty string; (ii) Search in the new string.

let text = `Hey "aaa bbbb &&&&&&" !@# "hahaha 123 %%%" !!!`;

let newText = text.replace(/"(.*?)"/g,"");

console.log(newText);

let matches = newText.match(/\W/g);

console.log(matches);

Regular expression with an exception

2 Answers2