" gs will create a substitution command to replace the last yanked string with
" the last inserted string over a motion.
"
" This is useful when renaming a variable for example, one can place the cursor
" over the varibale to rename and type:
"
" ciwnew_variable_name<esc>gsiB
"
" and this will replace that variable name with 'new_variable_name' inside the
" Body.

noremap  <silent> gs :set operatorfunc=<SID>do_subst_enter<cr>g@
vnoremap <silent> gs :call <SID>v_do_subst_enter()<cr>

" gS is like gs, except it:
"
"  * doesn't feed a newline at the end
"  * doesn't wrap the string to substitue in word boundaries.
noremap  <silent> gS :set operatorfunc=<SID>do_subst_no_enter<cr>g@
vnoremap <silent> gS :call <SID>v_do_subst_no_enter()<cr>

function! s:do_subst_enter(...) abort
  call s:do_subst_priv("'[", "']", v:true)
endfunction

function! s:do_subst_no_enter(...) abort
  call s:do_subst_priv("'[", "']", v:false)
endfunction

function! s:v_do_subst_enter(...) abort
  call s:do_subst_priv("'<", "'>", v:true)

endfunction

function! s:v_do_subst_no_enter(...) abort
  call s:do_subst_priv("'<", "'>", v:false)
endfunction

function! s:do_subst_priv(m0, m1, do_enter) abort
  let [_, lnum0, _, _] = getpos(a:m0)
  let [_, lnum1, _, _] = getpos(a:m1)

  " Need to call feedkeys() because @. may contain special characters like
  " backspace.
  call feedkeys(
        \ printf(
        \ ":%s %d,%d s/\\V%s%s%s/%s/g%s",
        \ a:do_enter ? "silent!" : "",
        \ lnum0,
        \ lnum1,
        \ a:do_enter ? "\\<" : "",
        \ escape(@", '/\'),
        \ a:do_enter ? "\\>" : "",
        \ escape(@., '/\'),
        \ a:do_enter ? "\n" : ""))
endfunction