$rreplace capture group?

MusicBrainz Picard
,
1

Can the $rreplace function replace the searched string with a capture group from within the string? If so, how?

2

Yes, you can. E.g. use “\\1” for the first capture group. Note the double backslash, which is needed to escape the backslash in tagger script.

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3

ah, thanks. I get really confused about how many backslashes I need for what.

4

Yeah, escaping can be confusing. Especially with regexes or multiple languages embedded in each other. As a side note, writing this here in the forums is also not easy. I had to experiment with the number of backslashes until it displayed correctly (you need to write 3 in order for it to display the whole thing correctly with two).

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5

Oh yeah, i was wrestling with that in another thread. You can get around it with the “preformatted text” option.

6

To make it more difficult, when I was trying to figure out the forum escaping on another thread, I was trying to get it working in code blocks. For some reason, those seem to use a completely different progression, and other numbers don’t seem to be affected:

  1. \1 - \1 - \2 - \2
  2. \\1 - \1 - \\2 - \2
  3. \\\1 - \\1 - \\\2 - \\2
  4. \\\\1 - \\1 - \\\\2 - \\2

I eventually wound up separating the backslashes with a zero-width space (U+00A0), and putting up a warning that it should be typed – not copied – into the Picard script. I’m not actually sure there’s any way to format an even number of slashes followed by a one in code here, as even <tt> tags have that issue.

EDIT: Found a way to do so, at least for the inline code blocks: put two of the graves between the slashes and the number (\1\\\1\11\1 results in \\``1, but the string to get the first, non-code-block display there is rather horrific). Not sure how to get that working with the full-line code indenting, though.

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7

Could somebody tell me what the required syntax for using named capture groups is?

In $rreplace I’ve tried setting them using:

(?{name}\w)

and then replace with:

${name}
${name} (prepended by a slash that the forum removes)
\{name}

but they all fail?
What is the correct syntax for this?

8

The group is created with (?P<name>\w) and used in the replacement with \g<name>.

In a taggerscript this might look like this:

$rreplace(foobar,\(?P<name>foo\),x\\g<name>x)

This will result in “xfooxbar”.

9

Thank you outsidecontext, that’s working well.
(I couldn’t find it documented anywhere)

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