Cut text with substitute into specific register & paste it back

Question

As I see the substitution command e.g.:

:% s/a/b/

puts a into the register "/ but the text that is being replaced is not saved in a register. Now, I would like to replace a with b but keep the result of a in a specific register where I can any moment retrieve it and paste it back at the same position where it was. I mean something like this:

Replace the text:

:% s/^\(.*\)\t\(.*\)/\2/g

Retrieve it from register "z and paste it back where it was:

:% s/^/\=@z/g

I think it should be pretty simple but I couldn't find anything related.

Answer 1

By default, the matched text in a substitution, won't be captured into a register, however it will always be available as atom & in the replace part of your :s command.

Having said that, you can of course store the matched text inside a specific register using the special atom \=.

So for example this:

    function StoreAndReplace(submatch)
        call setreg('z', a:submatch)
        return a:submatch . '_'. getreg('z')
    endfunction

and then running :%s/\w\+/\=StoreAndReplace(submatch(0))/g

will store the matched text in register z and replace the matched text by itsself + the register contents. However this is just a funny way to say:

:%s/\w\+/&_&/g

So one usually just uses the later and not the former way of doing it (especially since the content of the register will be overwritten the next time a replacement is performed).

Answer 2

You might want &, which is the original matched pattern:

:% s/^\(.*\)\t\(.*\)/&\2/g

Also, when you do a search (or a substitution), your search regex is stored in the register /, you can paste it for example with:

"/p

Answer 3

Yank all the matching text first, then do your substitute:

1. Clear a register: qaq
2. Set a mark at the original point: gg/pattern then mo
3. Yank text: :g//yank A
4. Substitute: :%s//replacement/flags

Now paste: 'o"ap

The paste will paste all of the matching text at the location of the first match pre-substitution.

If you want to save each match and the line it came from, I’d write a function to create a buffer-local dictionary (line -> text assuming one match per line, or line -> { column -> text }—dict of dict—for multiple matches anticipated), loop over the matches, grab the text and line number for the dicts, then do the substitution. Then you could write a separate function to "restore" from this dictionary based on line (and column)

Answer 4

@Christian Brabandt:

Thanks! I meant something like this:

<text11>\t<text12>
<text21>\t<text22>
...
<textM1>\t<textM2>

remove all text together with the tab & save it into a register:

<text12>\t
<text22>\t
...
<textM2>\t

and then be able to retrieve it from the register any time and place it back exactly where it was. But the example is simple because the removed text starts on the left. What if I wanted to remove text from x to y characters for every line?