loading back-reference groups "shortcut"

Question

I'm looking for a shortcut for loading back-reference groups using the same separator. Such a beast may not exist but it would be useful to me if it does. An example:

Starting with this string

:111 222 333 444 555

applying this pattern

:%s/\(\d\+\) \(\d\+\) \(\d\+\) \(\d\+\) \(\d\+\)/\5 \4 \3 \2 \1/g

will give me this result

:555 444 333 222 111

What I'm looking for is something to replace the match,

:\(\d\+\) \(\d\+\) \(\d\+\) \(\d\+\) \(\d\+\)

by giving it a pattern and a separator, and have it load as many groups as match.

::%s/<"\(\d\+\) ">/\5 \4 \3 \2 \1/g

Is there a way to do this? Thanks!

Answer 1

Many ways to do it!

Awk

$ awk '{for(i=1;i<=NF/2;i++) { t = $(NF-i+1); $(NF-i+1) = $i; $i = t; } print}' inpout.txt > output.txt

Prettier version of awk program:

{
    for (i=1; i<=NF/2; i++) {
        t = $(NF-i+1);
        $(NF-i+1) = $i;
        $i = t;
    }
    print
}

From inside Vim using filter, :!:

:%!awk '{for(i=1;i<=NF/2;i++) { t = $(NF-i+1); $(NF-i+1) = $i; $i = t; } print}'

Perl

From: Swapping an unlimited number of columns:

:%!perl -lane 'print join " ", reverse @F'

Pure Vim:

Use split(), join(), and reverse() to parse & reverse each line.

:g/^/call setline('.', join(reverse(split(getline("."), ' ')), " "))

For more help see:

:h :g
:h :call
:h setline()
:h getline()
:h join()
:h reverse()
:h split()