There are some good regex tester sites out there. Here’s one and a search for others. It really helps in debugging regular expressions. Generally you add in test data and the regex, and the site will highlight the strings it matches.
Build and test regular expressions regex. Make a free account here to save your regexes. https://regex101.com/

I suppose, but I don’t believe it uses the same regular expression engine as Notepad++, so it is of limited usefulness if you are going to use Notepad++ to do your regular expression searches and replacements.

I’m wondering if this needs to be added to the Regex FAQ or another thread.

Why would it need to be added where it already exists?

Or were you not aware that we have two different regex FAQ entries?

The second was the one discussed in this original topic: a table of contents of “generic” regex at https://community.notepad-plus-plus.org/topic/22673/faq-desk-generic-regular-expression-regex-formulas

But the much earlier regex FAQ explains where to get regex help, including links to the Notepad++ regex documentation, plus links to a lot more “regex tester” sites than you mentioned: https://community.notepad-plus-plus.org/topic/15765/faq-desk-where-to-find-regular-expressions-regex-documentation

Also, here’s an example with example data. https://regex101.com/r/Hfly86/1

There are some good regex tester sites out there. Here’s one and a search for others. It really helps in debugging regular expressions. Generally you add in test data and the regex, and the site will highlight the strings it matches.

Build and test regular expressions regex. Make a free account here to save your regexes. https://regex101.com/
Search for more: https://search.brave.com/search?q=free+account+test+regular+expression&source=web

I hope this is helpful!

For now, it’s linking to the in-thread versions of these generic expressions… but I highly encourage the developers of the expression to spin off a new blog post for each generic regex.

Here’s an example:
The original “match entire line OR regex” above is (?-s)(?:(?=.*Bob|.*Ted))^.*(?:\R|\z)
For my data, that one took between one and two minutes to run.
If I change the regex to (?-s)^(?=.*?(?:Bob|Ted)).+, that one runs so quickly that it is hard to time, except to say maybe it takes a second or so.

Probably all of the regexes I presented in my table above could be better optimized. :-(

My conclusion is that pointing novices at regular expressions here and expecting them to solve their own related problems may not be super-successful.

That’s why I posted here, rather than separately. This thread is for “developing” the generic expressions, with lots of back and forth. The “final version” will be published to its own separate thread. (I probably shouldn’t’ve posted a link back to here from the inspiration thread, because this one wasn’t ready yet)

I think your table is a good practical example of how to use it.

So maybe some really concrete examples help. In that light, my contribution will be how to match entire lines meeting the logic criteria that Peter brought to the table.

Say you want to match some particular combination of Bob and Ted on a line – here’s information on doing that:

I took a little liberty with Peter’s original “notes” table column; changed it up a bit. Also, obviously I only did a “two term” example.

Maybe I’m off-base and this doesn’t provide additional insight on exactly how to use Peter’s info, but hopefully it does.

Updating with n-term rather than just two-term:

Nice use of a table in a posting here, as well. :-)
Seriously, valuable information here. Kudos.

Now, Peter, I think it would be worth, in the general case, to add a ^ anchor, right in front of all these formulas !

The logic itself is independent of what you anchor it in. My two usage examples in my first post about “Logic Gates for Regular Expressions” show that you can use these standalone generic anchored either per-line or per-file depending on what you wrap around them. With generic, you could even stick these after some other match on the line, saying “after some prefix, match aaa or bbb” or similar. Hence, I didn’t want to specify the anchors in my generic expressions.

I gave a similar answer to @vijay-s ( refer here ), but Peter BRILLIANTLY beat me at it and gives us a complete panel of the look-aheads to use in order to simulate the main logical combinations !

Now, Peter, I think it would be worth, in the general case, to add a ^ anchor, right in front of all these formulas !

Best Regards,

guy038

I’m disturbed that some of your aaa in the first code block appears in italics – how does this happen in a code block?

It appears NodeBB isn’t treating all code blocks the same. But while it was italicizing, it fortunately wasn’t taking any characters away, so those were the expressions I meant to convey.

Giving the explicit txt filetype for the block:

OR      (?=.*aaa|.*bbb)
AND     (?=.*aaa)(?=.*bbb)
XOR     (?=.*aaa)(?!.*bbb)|(?!.*aaa)(?=.*bbb)
NOR     (?!.*aaa)(?!.*bbb)
NOR     (?!.*(aaa|bbb))
NAND    (?!(?=.*aaa)(?=.*bbb))

Hmm, I’m disturbed that some of your aaa in the first code block appears in italics – how does this happen in a code block?

Usually we see it if someone tries to do regular expressions without a code block, then the * turn some parts of the text into italics.

This recent discussion gave me the impetus to flesh it out into a generic table.

Logic Gates for Regular Expressions

OR      (?=.*aaa|.*bbb)
AND     (?=.*aaa)(?=.*bbb)
XOR     (?=.*aaa)(?!.*bbb)|(?!.*aaa)(?=.*bbb)
NOR     (?!.*aaa)(?!.*bbb)
NOR     (?!.*(aaa|bbb))
NAND    (?!(?=.*aaa)(?=.*bbb))

Depending on . matches newline setting, these expressions either mean “this line” matches or “this file” matches

For example, if you wrap each of those inside (?-s)(×××)^.*$ (ie, use the expression above instead of ×××), it will select each of the lines marked T (TRUE), depending on which expression you use

text          | OR | AND | XOR | NOR | NOR | NAND
--------------|----+-----+-----+-----+-----+------
aaa other aaa | T  |     | T   |     |     | T
aaa other bbb | T  | T   |     |     |     |
aaa other ccc | T  |     | T   |     |     | T
bbb other aaa | T  | T   |     |     |     | 
bbb other bbb | T  |     | T   |     |     | T
bbb other ccc | T  |     | T   |     |     | T
ccc other aaa | T  |     | T   |     |     | T
ccc other bbb | T  |     | T   |     |     | T
ccc other ccc |    |     |     | T   | T   | T

Similarly, wrapped as (?s)\A^(×××). it will select/match the first character of every file that matches the logic expression

• FIND = (?i-s)\A(^(?!DNM).*$\R*)+\z

Per @guy038’s improvement in the other thread, the $ shouldn’t really be outside of the DNM, so let’s just rework the generic to

• FIND = (?i-s)\A(^(?!DNM).*\R?)+\z

can be spun off into its own blog post

or FAQ Desk entry, or post in a FAQ desk entry… however we end up wanting to structure the “publish the generic regex sequence” entries.

My thoughts on that:

• I don’t want yet another category in the forum. Either Blogs or FAQ Desk should be sufficient
• If it’s in Blogs, I would lobby for each generic sequence to get its own Topic
• If it’s in FAQ Desk,
  • I could accept a single Topic with multiple Replies, one reply per description. But that would quickly get overwhelming, I think.
  • But even better, I think is a single Topic with a link to each of the individual blogs; after someone posts a generic expression Blog, then Guy or another moderator could edit the FAQ Desk entry to point to the new Blog entry

Find a file that never contains a line that matches a specific expression

• FIND = (?i-s)\A(^(?!DNM).*$\R*)+\z
• DNM means “does not match”, and is any regular expression which should not be found as a complete line anywhere in the file

As far as I could tell (in that other thread), this would work to look for a whole line that matches DNM and then fail the search because of it.

For my small tests, this formula worked. But I am sure there are gotchas I’ve missed.

For example, I haven’t tried, but I bet that larger files will not work, because of how much memory gets gobbled by this expression. Is there a way to improve this so that it becomes large-file agnostic?