search last substitution

Question

After doing

:%s/foo/bar/g

I can type

:<C-r>/

to place foo into the command line.

How can I place bar into the command line?

I ultimately want to do a series of:

:%s/foo/bar/g
:%s/bar/baz/g
:%s/baz/qux/g

etc., inspecting the resulting source file's outputs in-between (and don't want to rely on replace-undo, <C-r>/ because I might edit the file manually in-between too)

Answer 1

You can search for the last used substitute string with /~/. This should work as long as the substitute string does not contain any specials like \0...\9, \U, \L, etc.

Answer 2

<C-r>/ inserts a special register "/ (the last search string) at the actual position in the command line. Type :register and you'll see all registers with their content. There is no register for the subtitute-text.

Register are AFAIK the only way to keep such informations.

You could write a vim function, that extracts the replacement part of the substition command stored in register ": with a regular expression. You could bind that function to a key. But that only works as long as you do not enter another command, which would overwrite the ": register.

Another idea: You have to type foo, bar and baz at least once, you could instead search for them in the text, highlight them with v and yank them into a separate register:

\foo<CR>vll"ay
\bar<CR>vll"by
\baz<CR>vll"cy

Now you can use the registers as long as you want (as you don't overwrite them).

:%s/<C-r>a/<C-r>b/g
:%s/<C-r>b/<C-r>c/g
:%s/<C-r>c/qux/g