Combining .net and powershell regex capture groups syntax

Question

I'm having trouble combining powershell native regex capture group syntax $n with the .net one $args.groups[n].value. The HTML code is as follows:

ab

ab

ab [ap]

Ⅰ.adv

 1) (weg, entfernt) off;

  zur Post geht es an der Kreuzung links ~ the post office is off to the left at the crossroads;

  ~ sein to be out in the sticks;

  weit ~ sein [o liegen] to be far away;

  das Lokal ist mir zu weit ab the pub is too far away;

  das liegt zu weit ~ vom Weg that's too far off the beaten track

 2) (abgetrennt) off;

  ~ sein fam to be broken [off];

  mein Knopf ist ab I've lost a button;

  erst muss die alte Farbe ~ first you have to remove the old paint

 3) (in Befehlen) off;

  ~ ins Bett! off to bed!;

  ~, ihr beiden, Hände waschen! off you two go, and wash your hands!;

  ~ nach Hause! off home with you!;

  ~ in/auf dein Zimmer! go to your room!;

  ~ nach oben/unten! up/down we/you etc. go!;

  ~ sofort as of now;

  ~ und zu [o NORDD an] now and then

 4) (abgehend) from;

  der Zug fährt ~ Köln the train departs from Cologne;

  Frankfurt ~ 19 Uhr, New York an 8 Uhr departing Frankfurt [at] 19.00, arriving New York [at] 8.00 

Ⅱ.präp +dat

 1) (räumlich) from

 2) (zeitlich) from;

  ~ wann ...? from when ...?

 3) (von ... aufwärts) from;

  Kinder ~ 14 Jahren children from the age of 14 up

 4) ökon ex;

  Preis ~ Fabrik/Werk price ex factory/works

 5) SCHWEIZ (nach der Uhrzeit) past;

  Viertel ~ 8 quarter past eight

 6) SCHWEIZ (von) on;

  ~ Kassette on cassette

I want to insert roman numbers into the tags. This my code which is not working:

$content = [System.IO.File]::ReadAllText("C:	est.txt", [System.Text.Encoding]::UTF8)
$result  = [regex]::Replace( $content, '(?smi)(?:(?!
).)+

	(?:(?!
).)+(?:(?!|	).)+(?=|	)',
{$args.value -replace '()', "$1$args.groups[1].value$2"})

How can I mix these two different syntax into one piece of code to get my desire result?

Mathias R. Jessen · Accepted Answer

There's only one syntax - -replace internally calls Regex.Replace(), and Regex.Replace() also supports $N references.

Your problem is two-fold - first, when you use double-quotes, like so: "$1", PowerShell will attempt to expand/resolve $1 as a variable before the substitution pattern is passed to -replace.

Second problem is that PowerShell only expands variable values in double-quoted strings, not whole expressions. For that, you need to enclose the expression in a subexpression $().

So, either escape the $ with a backtick (`) and enclose the expression in $(), or use a single-quoted string:

$args.value -replace '()', "`$1$($args.groups[1].value)`$2"

... or prepare the string separately before calling -replace, perhaps with the -f string format operator:

$sub = '$1{0}$2' -f $args.Groups[1].Value
$args.Value -replace '()', "`$1$($args.groups[1].value)`$2"

If you switch to a newer version of PowerShell (6.1 or newer), you don't need to call Regex.Replace directly to take advantage of a dynamic match evaluator:

$content -replace $pattern,{
  return $_.Value -replace '()', "`$1$($match.Groups[1].Value)`$2"
}

Combining .net and powershell regex capture groups syntax

Answers (1)

Related Questions