Replace character in capture group

M Andre Z Eckenrode

Ok, so it looks like I can use:

(?:()|(<\/span>)|<\/span><\/p>)

…but not:

(?:()|(<\/span>)\1|\2<\/p>)

…so I think I’ve learned that numbered backreferences used in alternation sequences are unique for each sequence. That wasn’t clear to me from the online docs for NPP and Boost Perl Regular Expression Syntax 1.70.0, but I guess makes sense now that I think about it. :-)

Alan Kilborn

@M-Andre-Z-Eckenrode said in Replace character in capture group:

…but not:

Not 100% sure because I haven’t followed the preceding in a super-detailed fashion, but maybe what you’re looking for is called a “subroutine call” and not a “backreference”?

The syntactical difference is:

\1 🡢 backreference
(?1) -> subroutine

See more in this excellent posting: https://community.notepad-plus-plus.org/post/56447

If I’m totally off-base, well, at least the “excellent posting” reference contains some otherwise good stuff. :-)

M Andre Z Eckenrode

@Alan-Kilborn said in Replace character in capture group:

maybe what you’re looking for is called a “subroutine call” and not a “backreference”?
See more in this excellent posting:

I don’t THINK I’m confusing the two — I’m actually trying to utilize both — though considering my track record with this particular excercise, it wouldn’t come as a complete shock to learn otherwise. But thanks in any case for the link to that truly informative post. I think I could, however, benefit from many working examples of usage in various situations.

As far as named capture groups go, I can’t get any of the syntaxes listed in the post and the online NPP doc to actually work in NPP. For example, given text ABCDEFGHIJKLMNOPQRSTUVWXYZ, and search expression ABC(?<Name>.+?)XYZ, I get the following:

Replacement Expression		Result
------------------------------------------
\g<Name>             	=	g<Name>
\g'Name'             	=	g'Name'
\g{Name}             	=	g{Name}

Equivalent results using \k. Do any of these actually work for anybody else?

Alan Kilborn

@M-Andre-Z-Eckenrode said in Replace character in capture group:

I can’t get any of the syntaxes

If I use this as the replace-with expression for your search-for expression and data:

find: ABC(?<Name>.+?)XYZ
repl: abc_$+{Name}_xyz
data to search: ABCDEFGHIJKLMNOPQRSTUVWXYZ

I obtain:

abc_DEFGHIJKLMNOPQRSTUVW_xyz

I tell you that because you were asking about “replacement expression”.

However, your examples show you were trying to use \g which I believe only works in the find expression. Example:

find: (?<Name>t...)ING\g<Name>

which would match:

data to search: testINGtest or testINGtrip

A similar but distinctly different example:

find: (?<Name>t...)ING(?&Name)

which would match:

data to search: testINGtest or tripINGtrip but not testINGtrip

PeterJones

@M-Andre-Z-Eckenrode ,

I can’t get any of the syntaxes listed … Replacement Expression

@Alan-Kilborn said in Replace character in capture group:

I believe only works in the find expression

You are correct.

And you weren’t the first person this week to not notice that the \g and \k syntaxes are in the search section, and not in the replacement section (which tried to be explicit that any syntax not mentioned in the replacement section was not valid in the replacement field, but has apparently failed).

Could you both look at the proposed capture groups and backreferences phrasing and substitution phrasing , and make sure that the updated sections makes the distinction more clear?

—
Note to future readers: those “phrasing” links are to a temporary branch, and in the future, they will not work. https://npp-user-manual.org/docs/searching/ is the official location of the search documentation, and https://github.com/notepad-plus-plus/npp-usermanual/blob/master/content/docs/searching.md is the master github source for the document.

M Andre Z Eckenrode

@Alan-Kilborn said in Replace character in capture group:

repl: abc_$+{Name}_xyz
your examples show you were trying to use \g which I believe only works in the find expression.

Aha! Looks that’s true in NPP — though \g<Name> actually DOES work in PCRE replacement expressions at Regex101.

Thanks for the education.

Alan Kilborn

@M-Andre-Z-Eckenrode

DO NOT rely on regex101 for the more esoteric aspects of regex. Doing so, and then intending to use the results in Notepad++ will cause frustration. Sure, okay, for simple cases, but the caliber of stuff you have been discussing in this thread is going to be different in N++ and regex101.

M Andre Z Eckenrode

@PeterJones said in Replace character in capture group:

Could you both look at the proposed capture groups and backreferences phrasing and substitution phrasing , and make sure that the updated sections makes the distinction more clear?

Looks good to me so far, though coming from a fairly green regex user like me, I’d take that with a grain of salt. :-)

On a tangent here, I’ve noticed, on occasion when doing find/replace operations, that the In selection checkbox was sometimes ghosted (not available to check or uncheck), which I keep meaning to compile a list of circumstances for presentation and inquiry in these forums sometime. I notice that in both official and proposed versions of the doc, there seems to be no mention of any limitations on when the In selection checkbox is available. There seem to be some known limitations (at least one of which is mentioned here). Maybe they should be added to the docs?

M Andre Z Eckenrode

@Alan-Kilborn said in Replace character in capture group:

the caliber of stuff you have been discussing in this thread is going to be different in N++ and regex101.

I think I’ve already made it fairly clear, in my previous posts to this thread, that that’s what I’m finding to be the case.

Alan Kilborn

@M-Andre-Z-Eckenrode said in Replace character in capture group:

I think I’ve already made it fairly clear, in my previous posts to this thread, that that’s what I’m finding to be the case.

Perhaps, but I get the feeling you might be holding on to regex101 a bit much. :-)

Plus, I’m kind of a late joiner to this thread; there’s a lot of content.

Alan Kilborn

@M-Andre-Z-Eckenrode said in Replace character in capture group:

In selection checkbox was sometimes ghosted

In selection checkbox enabled condition: A single selection of one or more characters, that is NOT a column block selection.

Note that the checkbox’s appearance status can only be relied upon when you actually switch input focus to the find (family) window – upon activation the code runs a check to make sure you have the proper type of selection, and updates the checkbox and its state at that time.

PeterJones

@M-Andre-Z-Eckenrode said in Replace character in capture group:

Looks good to me so far

Thanks. Submitted PR #127. Hopefully, it will make it in before the next release of the npp-user-manual.org website.

Alan Kilborn

@PeterJones said in Replace character in capture group:

Looks good to me so far

Looked fine to me as well.
Thanks for your fine attention to the manual.
I just need to read it more when I have trouble with things. :-)

guy038

Hello, @peterjones,

Sorry, I’ve just seen your post where you asked people to verify the N++ official documentation ! I’ll try to have a look, myself, very soon. It would be better to do it before the next release of the website !

But, as I said to Alan, at the moment, my TO DO list, concerning N++ or else, is getting much longer ;-))

Cheers,

guy038