How to use regex to indent code in notepad++

Question

for example I have the following code

Module MPI
    Use MPI
    !
! MPI info
    If (true) Then
        Print *, \'\'
! empty line 1
! empty line 2
    End If
          


        

Answer 1

Since the engine is already passed on a comment line to indent it, I think it is impossible to use the same entire edited line for the next match to get the number of spaces. So I think you have to repeat the same replacement more times. Try with:

^(\s*)([^!\s].*?\r\n(\1\!.*?\r\n)*)\s*\!

always replacing it with $1$2$1!.

Like I said in the comment, if you have at most N consecutive comment lines, you will click on the "replace all" button N times

Answer 2

Using the search text ^( +)(.*\R)(!) and the replace text \1\2\1\3 then clicking on "Replace all" twice does what is wanted on the sample text. I cannot see a way of doing this in one pass.

The expression looks for a line with leading spaces followed by a line starting with a !. The capture groups are the leading spaces in \1, the rest of that line including the newline in \2 and the leading ! in \3. The replacement just assembles the captures in the right order. Note that you could omit the capture group around the ! and just have an explicit `! in the replacement, but I like to use captures in such contexts as they often allow for shorter replacements (although not in this case) and easier enhancements.