From 9e99546a2dc05803ded7a664cb319244d91a010b Mon Sep 17 00:00:00 2001
From: Josh Rahm <rahm@google.com>
Date: Fri, 4 Apr 2025 17:36:05 +0000
Subject: Change how the substitute works.

The strategy is now, what was the word before the text was changed, and
what is it after, and have that be the search/replace.
---
 plugin/substitute.vim | 50 ++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 48 insertions(+), 2 deletions(-)

diff --git a/plugin/substitute.vim b/plugin/substitute.vim
index 47de404..f06afb9 100644
--- a/plugin/substitute.vim
+++ b/plugin/substitute.vim
@@ -20,6 +20,52 @@ vnoremap <silent> gs :call <SID>v_do_subst_enter()<cr>
 noremap  <silent> gS :set operatorfunc=<SID>do_subst_no_enter<cr>g@
 vnoremap <silent> gS :call <SID>v_do_subst_no_enter()<cr>
 
+" Hotkey for replacing the most recently searched matches.
+noremap <C-s> <esc>:<C-u>%s//
+
+let s:entered_with_change = v:false
+let s:entered_with_append = v:false
+
+let s:old_word=''
+let s:new_word=''
+
+let s:override_word = ''
+function! OverrideChange()
+  let s:entered_with_change = v:true
+  let s:override_word = expand('<cword>')
+  return ''
+endfunction
+
+function! s:save_register_on_change()
+endfunction
+
+function! s:save_old_word() abort
+  if s:entered_with_change
+    let s:old_word = s:override_word
+  else
+    let s:old_word = expand("<cword>")
+  endif
+endfunction
+
+function! s:save_new_word() abort
+  if s:entered_with_change
+    let s:entered_with_change = v:false
+    let s:new_word = expand("<cword>")
+  else
+    let s:new_word = expand("<cword>")
+  endif
+endfunction
+
+augroup FieldMarshalSubstitute
+  au!
+  autocmd InsertEnter * call s:save_old_word()
+  autocmd InsertLeave * call s:save_new_word()
+augroup END
+
+noremap <expr> c OverrideChange() . 'c'
+noremap <expr> s OverrideChange() . 's'
+noremap <expr> a OverrideChange() . 'a'
+
 function! s:do_subst_enter(...) abort
   call s:do_subst_priv("'[", "']", v:true)
 endfunction
@@ -50,8 +96,8 @@ function! s:do_subst_priv(m0, m1, do_enter) abort
         \ lnum0,
         \ lnum1,
         \ a:do_enter ? "\\<" : "",
-        \ escape(@", '/\'),
+        \ escape(s:old_word, '/\'),
         \ a:do_enter ? "\\>" : "",
-        \ escape(@., '/\'),
+        \ escape(s:new_word, '/\'),
         \ a:do_enter ? "\n" : ""))
 endfunction
-- 
cgit