Text properties and Extended marks

--- textprops.vim
+++ extmarks.vim
@@ -1,14 +1,7 @@
 scriptencoding utf-8

-let s:dir_type_name = 'myfiler_dir'
-let s:file_type_name = 'myfiler_file'
-
-if empty(prop_type_get(s:dir_type_name))
-    call prop_type_add(s:dir_type_name, {'highlight': 'String'})
-endif
-if empty(prop_type_get(s:file_type_name))
-    call prop_type_add(s:file_type_name, {})
-endif
+" プラグイン用にnamespaceを定義してextmarkやhighlightを扱う
+let s:namespace = nvim_create_namespace('myfiler')

 function! s:filer(path) abort
     let s:bufnr = bufnr('%')
@@ -18,27 +11,34 @@
     call setline(1, ['..'] + map(copy(s:files), {_, v -> fnamemodify(v, ':t')}))
     setlocal nomodified buftype=nofile bufhidden=wipe

+    call nvim_buf_clear_namespace(s:bufnr, s:namespace, 0, -1) " 前のpathの分を一括でclearしておく
     let s:props = {} " idをkeyにしたdictにpropertyをもたせて管理する

-    let line = 1
+    let line = 0
     let paths = [fnamemodify(path, ':h:s?^\.$?\/?')] + map(copy(s:files), {_, v -> fnamemodify(v, ':p:gs?\?\/?')})
     for path in paths
-        let id = line " 特に支障がないので行数をid代わりにする
+        let id = nvim_buf_set_extmark(s:bufnr, s:namespace, 0, line, 0, {})
         let is_dir = isdirectory(path)
-        call prop_add(line, 1, {'length': len(getline(line)), 'type': is_dir ? s:dir_type_name : s:file_type_name, 'id': id})
+        if is_dir
+            call nvim_buf_add_highlight(s:bufnr, s:namespace, 'String', line, 0, -1)
+        endif
         let prop = {'path': path, 'is_dir': is_dir}
         let s:props[id] = prop
+
+        call nvim_buf_set_virtual_text(s:bufnr, s:namespace, line, [[string(prop), 'Comment']], {}) " デバッグに便利
         let line += 1
     endfor
 endfunction

 function! s:open() abort
-    let props = prop_list(line('.'))
-    if empty(props)
+    let index = line('.') - 1
+    " 現在行のextmarkをすべて取得する (:h api-indexing の通り-1は最終行(または列)を示す)
+    let marks = nvim_buf_get_extmarks(bufnr('%'), s:namespace, [index , 0], [index, -1], {})
+    if empty(marks)
         return
     endif

-    let prop = s:props[props[0].id]
+    let prop = s:props[marks[0][0]] " marks = [[id, line, col], ..]
     if prop.is_dir
         return s:filer(prop.path)
     endif