Substitution using groups from regex works only on one group out of three

Question

I want to replace if (condition) //comment \n\s*{ (\n - newline, \s* 0 or more whitespaces), or rather restructure it, so brace is on same line as if and comment is moved to next one and is indented by one tab more.

It's a Vim practice task, so please don't give me whole solution, instead help me understand what I'm missing.

My regex works and catches what I want (starting with comment on purpose):

:%s#\(//\)\(.\)*\n\(\s\)*{#{\r\t\3\1 \2#g

My replace pattern however doesn't catch groups, using \1 \2 \3 doesn't work. To be more precise, only \1 works.

I get a brace, a new line, one more indent as wanted, then groups (except for \1 (meaning //) are NOT there:

if (condition) {
    //

No comment text, no tabs/whitespaces aside from one I specifically put there. What am I missing?

Answer 1

Given this text

if (condition) //comment
    {

the following substitute

:%s#\(//\)\(.\)*\n\(\s\)*{#{\r\t\3\1 \2#g

gives:

if (condition) {
     // t

I don't fully understand, but \(.\)* would repeat the atom of capturing any single character zero or more times, resulting in capturing the last character of first line t

As the intention was to capture all the text following //, * should have been inside the capturing group. Same goes for \(\s\)*. The g flag is not needed as well

:%s#\(//\)\(.*\)\n\(\s*\){#{\r\t\3\1 \2#

which gives

if (condition) {
        // comment

Using the very magic modifier, the regex would be (see :h \v for help)

:%s#\v(//)(.*)\n(\s*)\{#{\r\t\3\1 \2#