Refactored retaining of unnamed register to be done in VimState.

plugin/UltiSnips.vim

@@ -256,7 +256,7 @@ function! UltiSnips_LeavingBuffer()
 endf
 
 function! UltiSnips_LeavingInsertMode()
-    exec g:_uspy "UltiSnips_Manager.restore_unnamed_register()"
+    exec g:_uspy "UltiSnips_Manager.leaving_insert_mode()"
 endfunction
 
 " }}}

pythonx/UltiSnips/__init__.py

@@ -168,10 +168,6 @@ class SnippetManager(object):
         while len(self._csnippets):
             self._current_snippet_is_done()
 
-        # needed to retain the unnamed register at all times
-        self._unnamed_reg_cached = False
-        self._last_placeholder = None
-
         self._reinit()
 
     @err_to_scratch_buffer
@@ -439,25 +435,14 @@ class SnippetManager(object):
                 self._current_snippet_is_done()
                 jumped = self._jump(backwards)
         if jumped:
-            self._cache_unnamed_register()
             self._vstate.remember_position()
+            self._vstate.remember_unnamed_register(self._ctab.current_text)
             self._ignore_movements = True
         return jumped
 
-    def _cache_unnamed_register(self):
-        """Save the unnamed register."""
-        self._unnamed_reg_cached = True
-        unnamed_reg = _vim.eval('@"')
-        if self._last_placeholder != unnamed_reg:
-            self._unnamed_reg_cache = unnamed_reg
-        self._last_placeholder = self._ctab.current_text
-
-    def restore_unnamed_register(self):
-        """Restores the unnamed register from the cache."""
-        if self._unnamed_reg_cached:
-            escaped_cache = self._unnamed_reg_cache.replace("'", "''")
-            _vim.command("let @\"='%s'" % escaped_cache)
-            self._unnamed_reg_cached = False
+    def leaving_insert_mode(self):
+        """Called whenever we leave the insert mode."""
+        self._vstate.restore_unnamed_register()
 
     def _handle_failure(self, trigger):
         """Mainly make sure that we play well with SuperTab."""

pythonx/UltiSnips/vim_state.py

@@ -31,6 +31,29 @@ class VimState(object):
         self._poss = deque(maxlen=5)
         self._lvb = None
 
+        self._text_to_expect = None
+        self._unnamed_reg_cache = None
+        self._unnamed_reg_cached = False
+
+    def remember_unnamed_register(self, text_to_expect):
+        """Save the unnamed register. 'text_to_expect' is text that we expect
+        to be currently contained in the register - this could be text from the
+        tabstop that was selected and might have been overwritten. We will not
+        cash that then."""
+        self._unnamed_reg_cached = True
+        unnamed_reg = _vim.eval('@"')
+        if unnamed_reg != self._text_to_expect:
+            self._unnamed_reg_cache = unnamed_reg
+        self._text_to_expect = text_to_expect
+
+    def restore_unnamed_register(self):
+        """Restores the unnamed register and forgets what we cached."""
+        if not self._unnamed_reg_cached:
+            return
+        escaped_cache = self._unnamed_reg_cache.replace("'", "''")
+        _vim.command("let @\"='%s'" % escaped_cache)
+        self._unnamed_reg_cached = False
+
     def remember_position(self):
         """Remember the current position as a previous pose."""
         self._poss.append(VimPosition())