Replace a string without changing case?

Question

Due to a quirk in the domain-specific language I am working with, I frequently face the task of (selectively, not globally) replacing term or TERM with word or WORD, respectively.

This means, I search case-insensitively for term, and want to replace that with word while keeping the uppercase / lowercase of the original term intact.

Since checking the whole of term for consistent upper-/lowercase would be difficult and is not really necessary, I would settle for uppercase / lowercase of word / WORD being decided on the first letter of term.

How could I achieve this?

Answer 1

Michaels Geddes' plugin keepcase (GitHub) has all you need:

:%SubstituteCase/\cterm/word/g

Other syntax elements from :substitute are also supported.

Answer 2

This can be handled by the :Subvert from the abolish plugin:

One time I had an application with a domain model called "facility" that needed to be renamed to "building". So, a simple search and replace, right?

:%s/facility/building/g

Oh, but the case variants!

:%s/Facility/Building/g
:%s/FACILITY/BUILDING/g

Wait, the plural is more than "s" so we need to get that too!

:%s/facilities/buildings/g
:%s/Facilities/Buildings/g
:%s/FACILITIES/BUILDINGS/g

Abolish.vim has your back. One command to do all six, and you can repeat it with & too!

:%Subvert/facilit{y,ies}/building{,s}/g