" Language: Vim script
" Description: Quickly replace the word that is under the cursor.
" Usage: Press the keys '<Leader>rr', type the new word, and 
"        then leave insert mode (<Esc>).
" License: MIT
" Author: James Cherti
" URL: https://www.jamescherti.com/vim-quickly-replace-word-under-cursor/

function! s:replace_word_under_cursor(...) abort
  let l:action = 'main'
  if len(a:000) > 0
    let l:action = a:000[0]
  endif
  
  "
  " Main action
  "
  if l:action ==# 'main'
    let b:replace_word_data = {}
    let b:replace_word_data['changenr'] = changenr()

    let l:regex_prefix = ''
    let l:regex_suffix = ''
    if mode() ==# 'n'
      normal! diw
      let l:regex_prefix = '\<'
      let l:regex_suffix = '\>'
    else
      echoerr 'Unsupported mode: ' . mode()
      return
    endif

    let b:replace_word_data['string'] = substitute(@@, '\v\n+$', '', 'g')
    let b:replace_word_data['escaped_string'] =
        \ '\V' . l:regex_prefix . 
        \ escape(b:replace_word_data['string'], '/\') . 
        \ l:regex_suffix
    startinsert

    augroup ReplaceString
      autocmd!
      autocmd InsertLeave * call s:replace_word_under_cursor('insert_leave')
    augroup END

    return
  endif

  
  "
  " Insert Leave
  "
  if l:action ==# 'insert_leave'
    autocmd! ReplaceString InsertLeave
    
    let l:new_string = expand('<cword>')
    if empty(l:new_string) 
      execute 'undo ' . b:replace_word_data['changenr']
      return
    endif
    
    let l:cursor_pos = getpos('.')
    execute 'keeppatterns silent! %substitute/' . 
        \ b:replace_word_data['escaped_string'] . '/' . 
        \ escape(l:new_string, '/\') . '/g'
    call setpos('.', l:cursor_pos)
    
    echo 'Replace: ' . b:replace_word_data['string'] . ' -> ' . l:new_string
    
    unlet b:replace_word_data
    return
  endif
endfunction

nnoremap <Leader>rr :call <SID>replace_word_under_cursor()<CR>Code language: Vim Script (vim)