This would be extremely helpful indeed, thank you!
As for the lookbehind, I hastily presumed it not being allowed since I got an error message instead of FLP starting the search, for my basic (and obviously wrong) try (?<=}.+?)searchstring(?=.+?}) (see below), sorry!
After reading your answer, I finally remembered that lookbehinds come, according to the specific regex flavor, with all sorts of general or flavor-specific limitations, so I looked that up again.
Basics: for
(lookbehind)searchtext(lookahead)
- positive (i.e. "look..." text must be there):
(?<=lookstring)searchtext(?=lookstring)
- negative (i.e. "look..." text must NOT be there):
the "=" is to be replaced by a "!" (for logical "NOT")
In the lookahead lookstring:
Any (!) regex allowed here except a lookbehind, even capturing groups (for the latter some exceptions in Tcl regex).
But in the lookbehind lookstring:
LOTS of problems/exclusions, according to the regex flavor, in Tcl not allowed at all it seems, in Perl/Python/etc.
- only fixed-length strings, and other limitations,
- alternation (i.e. the "OR" "|") only if the alternatives are of the same length (e.g. th(is|at) for this OR that),
- NO quantifiers (i.e. my (?<=}.+?) was obviously wrong, as would have been (?<=}.starsymbol) etc. (I write starsymbol, since the regex star symbol would close the italics here)),
- etc., etc., so I had been overly optimistic in thinking about an alternative for my (working) code (above in bold = 2 strings with NO "}" in-between).
It would not have made sense anyway since in the alternative I had in mind (= 2 strings in-between 2 "}") would have brought hit blocks as extensive as my code above: ("}" and then anything except a "}" as a lookbehind, but not possible this way)(searchstring1)(anything except a "}")(searchstring2)(anything except a "}" and then a "}").
On the other hand, there are use cases where the "full" page / chapter / subchapter / section / etc., having 1/2/3... search terms in combination, would be wanted, and there, a simple
(}.+searchstring1.+?searchstring2.+?})|(}.+searchstring2.+?searchstring1.+?}) (more complicated but doable for 3, 4...) would work fine (with starsymbol instead of the "+" in case if you want to provide for "possibly nothing" instead), so how to get the "}" or a similar separator character?
Since the FLP regex (as far as I have understood the help file / other answers here) will not work onto the original file but on a "text-only" version of that, least the command characters, sometimes the original page / chapter / section separator characters will not be available anymore for the FLP regex search; in such cases it should often be possible to do a simple search-and-replace, in the original application, for the specific separator codes over there, and replacing them with those codes plus another, otherwise not used special character which can then be searched for in FLP regex (e.g. my "}", a "¬" or any other such character which doesn't occur elsewhere in the text).
(And if that is not successful: I got the "}" from opening a copy (!) of one of my original files within a hex editor (there are free ones available), in which I was able to identify the "}" (which is not visible in the original application), which then is recognized by the FLP regex (i.e. not stripped off in-between). This may sound quite exotic, but it's successful in the end, and I know of no text or other such application which would provide a search for a combination of several search terms within the same subdivision as page, chapter...)
