refactor: use inserted_bytes pattern from vim

This covers all "small" inserts and deletes in insert mode, as well
as a few more cases like small normal mode deletes

vim-patch:8.1.0678: text properties as not adjusted for inserted text

src/nvim/change.c

@@ -359,6 +359,24 @@ void changed_bytes(linenr_T lnum, colnr_T col)
   }
 }
 
+/// insert/delete bytes at column
+///
+/// Like changed_bytes() but also adjust extmark for "added" bytes.
+/// When "added" is negative text was deleted.
+static void inserted_bytes(linenr_T lnum, colnr_T col, int added)
+{
+  if (added > 0) {
+    extmark_col_adjust(curbuf, lnum, col+1, 0, added, kExtmarkUndo);
+  } else if (added < 0) {
+    // TODO(bfredl): next revision of extmarks should handle both these
+    // with the same entry point. Also with more sane params..
+    extmark_col_adjust_delete(curbuf, lnum, col+2,
+                              col+(-added)+1, kExtmarkUndo, 0);
+  }
+
+  changed_bytes(lnum, col);
+}
+
 /// Appended "count" lines below line "lnum" in the current buffer.
 /// Must be called AFTER the change and after mark_adjust().
 /// Takes care of marking the buffer to be redrawn and sets the changed flag.
@@ -630,7 +648,7 @@ void ins_char_bytes(char_u *buf, size_t charlen)
   ml_replace(lnum, newp, false);
 
   // mark the buffer as changed and prepare for displaying
-  changed_bytes(lnum, (colnr_T)col);
+  inserted_bytes(lnum, (colnr_T)col, (int)(newlen - oldlen));
 
   // If we're in Insert or Replace mode and 'showmatch' is set, then briefly
   // show the match for right parens and braces.
@@ -676,7 +694,7 @@ void ins_str(char_u *s)
   assert(bytes >= 0);
   memmove(newp + col + newlen, oldp + col, (size_t)bytes);
   ml_replace(lnum, newp, false);
-  changed_bytes(lnum, col);
+  inserted_bytes(lnum, col, newlen);
   curwin->w_cursor.col += newlen;
 }
 
@@ -797,7 +815,7 @@ int del_bytes(colnr_T count, bool fixpos_arg, bool use_delcombine)
   }
 
   // mark the buffer as changed and prepare for displaying
-  changed_bytes(lnum, curwin->w_cursor.col);
+  inserted_bytes(lnum, col, -count);
 
   return OK;
 }

src/nvim/edit.c

@@ -5599,11 +5599,7 @@ insertchar (
     do_digraph(-1);                     /* clear digraphs */
     do_digraph(buf[i-1]);               /* may be the start of a digraph */
     buf[i] = NUL;
-    colnr_T col_start = curwin->w_cursor.col;
     ins_str(buf);
-    extmark_col_adjust(curbuf, curwin->w_cursor.lnum,
-                       (colnr_T)(col_start + 1), 0,
-                       (long)STRLEN(buf), kExtmarkUndo);
     if (flags & INSCHAR_CTRLV) {
       redo_literal(*buf);
       i = 1;
@@ -5614,9 +5610,6 @@ insertchar (
   } else {
     int cc;
 
-    extmark_col_adjust(curbuf, curwin->w_cursor.lnum,
-                       (colnr_T)(curwin->w_cursor.col + 1), 0,
-                       1, kExtmarkUndo);
     if ((cc = utf_char2len(c)) > 1) {
       char_u buf[MB_MAXBYTES + 1];
 
@@ -8507,14 +8500,6 @@ static bool ins_tab(void)
 
   temp -= get_nolist_virtcol() % temp;
 
-  // Move extmarks
-  extmark_col_adjust(curbuf,
-                     curwin->w_cursor.lnum,
-                     curwin->w_cursor.col,
-                     0,
-                     temp,
-                     kExtmarkUndo);
-
   /*
    * Insert the first space with ins_char().	It will delete one char in
    * replace mode.  Insert the rest with ins_str(); it will not delete any

src/nvim/ops.c

@@ -1644,8 +1644,6 @@ int op_delete(oparg_T *oap)
       curwin->w_cursor.col = 0;
       (void)del_bytes((colnr_T)n, !virtual_op,
                       oap->op_type == OP_DELETE && !oap->is_VIsual);
-      extmark_col_adjust(curbuf, curwin->w_cursor.lnum,
-                         (colnr_T)0, 0L, (long)-n, kExtmarkUndo);
       curwin->w_cursor = curpos;  // restore curwin->w_cursor
       (void)do_join(2, false, false, false, false);
     }
@@ -1685,7 +1683,6 @@ setmarks:
     if (oap->is_VIsual == false) {
       endcol = MAX(endcol - 1, mincol);
     }
-    extmark_col_adjust_delete(curbuf, lnum, mincol, endcol, kExtmarkUndo, 0);
   }
   return OK;
 }
@@ -4279,14 +4276,14 @@ format_lines(
         if (next_leader_len > 0) {
           (void)del_bytes(next_leader_len, false, false);
           mark_col_adjust(curwin->w_cursor.lnum, (colnr_T)0, 0L,
-                          (long)-next_leader_len, 0, kExtmarkUndo);
+                          (long)-next_leader_len, 0, kExtmarkNOOP);
         } else if (second_indent > 0) {   // the "leader" for FO_Q_SECOND
           int indent = (int)getwhitecols_curline();
 
           if (indent > 0) {
-            (void)del_bytes(indent, FALSE, FALSE);
+            (void)del_bytes(indent, false, false);
             mark_col_adjust(curwin->w_cursor.lnum,
-                            (colnr_T)0, 0L, (long)-indent, 0, kExtmarkUndo);
+                            (colnr_T)0, 0L, (long)-indent, 0, kExtmarkNOOP);
           }
         }
         curwin->w_cursor.lnum--;
@@ -4951,23 +4948,6 @@ int do_addsub(int op_type, pos_T *pos, int length, linenr_T Prenum1)
     curbuf->b_op_end.col--;
   }
 
-  // if buf1 wasn't allocated, only a singe ASCII char was changed in-place.
-  if (did_change && buf1 != NULL) {
-    extmark_col_adjust_delete(curbuf,
-                              pos->lnum,
-                              startpos.col + 2,
-                              endpos.col + 1 + length,
-                              kExtmarkUndo,
-                              0);
-    long col_amount = (long)STRLEN(buf1);
-    extmark_col_adjust(curbuf,
-                       pos->lnum,
-                       startpos.col + 1,
-                       0,
-                       col_amount,
-                       kExtmarkUndo);
-  }
-
 theend:
   xfree(buf1);
   if (visual) {

test/functional/api/mark_extended_spec.lua

@@ -475,6 +475,13 @@ describe('Extmarks buffer api', function()
     check_undo_redo(ns, marks[2], 0, 3, 1, 2)
   end)
 
+  it('deleting right before a mark works #extmarks', function()
+    -- op_delete in ops.c
+    set_extmark(ns, marks[1], 0, 2)
+    feed('0lx')
+    check_undo_redo(ns, marks[1], 0, 2, 0, 1)
+  end)
+
   it('deleting on a mark works #extmarks', function()
     -- op_delete in ops.c
     set_extmark(ns, marks[1], 0, 2)