Using gawk or sed to inplace change line after or before every other match - perl

Question

I am trying to change the comment format for many files. Currently I have
//-----------------------------------------------------------
// NAME : Class
// DESCRIPTION : Vague information
//-----------------------------------------------------------
The number of - may be different with each file, or even with each case. I would like something like this to keep readability with the rest of the code while still allowing compatibility with a documenting program:
//-----------------------------------------------------------
/*!
// NAME : Class
// DESCRIPTION : Vague information
*/
//-----------------------------------------------------------
But this is also acceptable, and for sure easier:
/*!
// NAME : Class
// DESCRIPTION : Vague information
*/
For a start, I have tried something like
$ gawk -i inplace '/^\/\/--.*/&&v++%2 {sub(/^\/\/--.*, "\/\*!")}' filename.cpp
and then
$ gawk -i inplace '/^\/\/--.*/{sub(/^\/\/--.*, "\*\/")}' filename.cpp
which obviously has some syntax errors; the goal was to change every odd instance of //---* with /*!, and then replacing //---* with */, and for just one file, instead of many .cpp and .h/.hpp files.

Answer 1

Given:
$ cat file
//-----------------------------------------------------------
// NAME : Class
// DESCRIPTION : Vague information
//-----------------------------------------------------------
With THIS regex, you can use perl:
$ perl -0777 -pE 's/^(\/\/-+\R)(\/\/[\s\S]*?)(^\/\/-+\R?)/\1\/\*!\n\2\*\/\n\3/gm' file
//-----------------------------------------------------------
/*!
// NAME : Class
// DESCRIPTION : Vague information
*/
//-----------------------------------------------------------
Perl also has an inplace option.

Answer 2

Using sed
$ sed -E 'N;s~-\n~&/*!\n~;s~\n/+-~\n*/&~' input_file
//-----------------------------------------------------------
/*!
// NAME : Class
// DESCRIPTION : Vague information
*/
//-----------------------------------------------------------

Answer 3

perl -0777 -wnE'
say s{ //-+\n\K (//.*?) (//-+\n) }{/*!\n$1*/\n$2}sgrx
' file_with_comment_blocks.txt
Broken into lines only for readability. Modifiers (at the end of regex) are:
s with it the . matches a newline as well
g repeat throughout the whole string ("global")
r so to return the new string (or the unchanged original). Used here for printing
x ignore spaces, so use them for readability (also allows newlines and #-comments)
This only prints so it can be redirected to a file for a result while it is safe for testing.
Or, change so to rewrite the file in-place
perl -0777 -i.bak -wnE'
s{ //-+\n\K (//.*?) (//-+\n) }{/*!\n$1*/\n$2}sgx
' file_with_comment_blocks.txt
If backup isn't wanted then use -i (no .bak). See Command-line switches in perlrun

Answer 4

I would harness GNU AWK for this task following way, let file.txt content be
//-----------------------------------------------------------
// NAME : Class
// DESCRIPTION : Vague information
//-----------------------------------------------------------
then
awk 'index($0,"//---")==1{++v;if(v%2){print;print "/*!"}else{print "*/";print};next}{print}' file.txt
gives output
//-----------------------------------------------------------
/*!
// NAME : Class
// DESCRIPTION : Vague information
*/
//-----------------------------------------------------------
Explanation: for lines starting with //--- (I use index String function to avoid need to escape /) I do increase v by 1 and then print current line followed by /*! in case v is odd else print */ followed by current line, then I instruct GNU AWK to go to next line to avoid duplicate printing, all others lines are just printed. After you are sure result is compliant with requirement you might add -i inplace after awk.
(tested in GNU Awk 5.0.1)

Answer 5

Using any awk:
$ awk '/^\/\/-+$/{ $0=( ++c%2 ? "/*!" : "*/" ) } 1' file
/*!
// NAME : Class
// DESCRIPTION : Vague information
*/
or if you prefer:
$ awk '/^\/\/-+$/{ $0=( ++c%2 ? $0 ORS "/*!" : "*/" ORS $0 ) } 1' file
//-----------------------------------------------------------
/*!
// NAME : Class
// DESCRIPTION : Vague information
*/
//-----------------------------------------------------------
To change the input file, if you have GNU awk change awk to awk -i inplace or with any awk add >tmp && mv tmp file at the end.

Answer 6

This might work for you (GNU sed):
sed '/^\/\/-\+$/{:a;N;/\n\/\/-\+$/!ba;s/\n.*\n/\n\/*!&*\/\n/}' file
Gather up lines that start and end //----------....
Prepend \n/*! and append */\n between the first and last newline of the collection.
Or if prefered:
sed '/^\/\/-\+$/{:a;N;/\n\/\/-\+$/!ba;s/^[^\n]*/\/*!/;s/\(.*\n\).*/\1*\//}' file
A "belt a braces" version of the first solution, that only applies to lines that begin and end as OP example with all lines commented inbetween:
sed '/^\/\/-\+$/{:a;N;/\n\/\/[^\n]*$/!{:b;P;D}
/\n\/\/-\+$/!ba;s/\n.*\n/\n\/*!&*\/\n/;Tb}' file