Can I remap <C-(key)> while replacing a character? If not, is there a workaround or hack?

Question

I have i-mapped <C-a>, <C-s> etc. to commonly used keys that I use often but find annoying to type normally, for example * and _. It works as expected in insert mode, but when executing a single-character replacement with r, I get some kind of escape sequence instead.

I've tried nnoremap r<C-(key)> character and nmap r<C-(key)> character, but seemingly-random things happen when i execute r<C-(key)>. Mapping to different characters (symbols) gives very different results. Prefixing the character with \ just makes nothing happen.

What is a way I can remap <C-(key)> while replacing a character?

Answer 1

This has to be done through the feature known as "language mapping". This feature allows entry of non-English/ASCII characters using a standard keyboard but more generally allows one to control the mapping of characters entered into a buffer which is what r emits.

You need to do two things:

1. Use lmap for the mapping rather than imap. E.g. :lnoremap <c-a> *
2. Enable language mapping. This can be done with :set iminsert=1 or by typing Ctrl^ (control-caret) while in insert mode.

Besides :h :lmap see :h 45.5, :h i_Ctrl-^ and :h 'iminsert'

Note that lmap also applies to characters entered while in Insert mode so lmap should be all you need for your general use case of replacing "annoying" characters with easier-to-type variants.