So after some thinking about this, I’ve decided that I don’t think the \A syntax is broken in Notepad++, and I don’t think that lookbehind assertions (either positive or negative) are broken in Notepad++ either. One just has to fully understand how Notepad++ searching works. And @guy038, in your post just above, where you talk about a “first problem” and a “second problem” and beyond…I have NO problem with how Notepad++ works in these cases, given my new thinking!
Every Notepad++ search has a “starting-point” when the user initiates a search, or that Notepad++ itself initiates after a successful match in the case where one of the “find all” searches (or a Find in Files) is conducted. Each starting-point has exactly NOTHING before it. YOU may SEE data before your caret when you initiate a Find Next, but Notepad++ doesn’t. And that, IMO, isn’t necessarily a broken search feature, it is just “the way it works”. To Notepad++, each starting-point appears the same as a start-of-file does–no data (aka NOTHING) comes before it.
At the beginning of your regex, an \A assertion or ANY valid negative lookbehind assertion will match the NOTHING right at a starting-point (i.e., that part of the regex will always succeed). Note that a negative lookbehind assertion doesn’t match the real data to the left of your caret, it matches the NOTHING. Example: Have 12345678 (only) in your buffer and your caret between the 4 and the 5. Do a regex search for (?<!4)5 and see that it matches the 5. The (?<!4) in this case allows the match because NOTHING is not 4. Some would call this regex behavior “broken”…because YOU the user can see the darned 4 right there!
While a search is “in-progress” on a buffer, however, no one would call negative lookbehind assertions broken. Example: Use the same buffer as before but have your caret between the 1 and the 2. Do a regex search for (?<!4)5 and see that there is no match. In this case there is a 4 before the 5 (the search is “underway” at this point and Notepad++ is looking at the buffer…and this time the 4 is a part of that buffer) so the assertion fails the overall match.
Side note: With “Wrap around” ticked during a search, if no match is found between the current caret point and the end-of-file, a second (internal) search is done by Notepad++, with a starting-point at the start-of-file. This is an additional opportunity for a match to happen at a “starting point”. For more info on the “2nd search”, see here…quite far into that thread… Although that thead discusses replacement, find a part of replacement, so it works the same way.
So that brings us back to the regex under discussion: (?<!\r|\n)^.
It will work like an “unbroken” \A in most cases. A possible problem with it comes when doing “multiple” searches with it (or when the user-starting-point isn’t the start-of-file). In those cases, if the previous action with it leaves the next starting-point at the start of any line, the next search will match right there – not only at start-of-file – which may not be what the user desires. (Again, it will match that case because the (?<!\r|\n) part will match the NOTHING and the ^ will hit).
The best way to use it as an \A-equivalent is to have the end of your regex not leave the next starting-point at any start-of-line.
So let’s go back to Terry’s original regex (or very close to it):
(?s)(?<!\r|\n)^((.+?)===========){5}(.+?)\K(===========)
When run on the OP’s sample data (duplicated a few times so that there are many more than 9 lines of =========== data) this will find exactly ONE match when a “find all” is done. That is because the end of the regex sets up the follow-on starting-point to NOT be able to match a start-of-line (needed by the ^ assertion).
Changing the regex slightly at the end:
(?s)(?<!\r|\n)^((.+?)===========){5}(.+?)\K(===========)\R
This one will result in multiple matches using a “find all” in the OP’s (extended) data, for reasons which should now be apparent. Thus it is worth pointing out in such a case that the (?<!\r|\n)^ regex is NOT what one normally thinks \A should be doing. So while it can be a \A substitute, it still has to be used with some amount of caution, and of course, understanding. :-)
Back to \A: You can be the judge of whether or not it is broken: The Boost documentation for \A says “Matches at the start of a buffer only” – does one consider the “buffer” to be the entirety of the Notepad++ editor tab data, or the starting-point(s) through a later point for a search? Your call. :-)
And now onto \G. In this thread , there are 3 conditions specified for where the \G assertion can match. I believe there is only ONE place it can match; hint: the “starting-point” of a search. :-)
