Implement restore unnamed register feature

autoload/neosnippet/handlers.vim

@@ -74,6 +74,16 @@ function! neosnippet#handlers#_all_clear_markers() "{{{
   endtry
 endfunction"}}}
 
+function! neosnippet#handlers#_restore_unnamed_register() "{{{
+  let neosnippet = neosnippet#variables#current_neosnippet()
+
+  if neosnippet.unnamed_register != ''
+        \ && @" !=# neosnippet.unnamed_register
+    let @" = neosnippet.unnamed_register
+    let neosnippet.unnamed_register = ''
+  endif
+endfunction"}}}
+
 function! s:is_auto_pairs() abort "{{{
   return get(g:, 'neopairs#enable', 0)
 endfunction"}}}

autoload/neosnippet/init.vim

@@ -57,6 +57,8 @@ function! s:initialize_others() "{{{
           \ call neosnippet#variables#set_snippets({})
     autocmd BufEnter *
           \ call neosnippet#mappings#_clear_select_mode_mappings()
+    autocmd TextChanged,TextChangedI *
+          \ call neosnippet#handlers#_restore_unnamed_register()
   augroup END"}}}
 
   if g:neosnippet#enable_auto_clear_markers

autoload/neosnippet/variables.vim

@@ -34,6 +34,7 @@ function! neosnippet#variables#current_neosnippet() "{{{
           \ 'target' : '',
           \ 'trigger' : 0,
           \ 'optional_tabstop' : 0,
+          \ 'unnamed_register' : '',
           \}
   endif
 

autoload/neosnippet/view.vim

@@ -408,6 +408,8 @@ function! s:expand_placeholder(start, end, holder_cnt, line, ...) "{{{
 
   if default_len > 0 && is_select
     " Select default value.
+    let neosnippet.unnamed_register = @"
+
     let len = default_len-1
     if &l:selection == 'exclusive'
       let len += 1