[filename] support detect new file status (#785)

* [filename] support detect new file status

* update readme about new file status

* add definition for new file

README.md

@@ -593,6 +593,7 @@ sections = {
     {
       'filename',
       file_status = true,      -- Displays file status (readonly status, modified status)
+      newfile_status = false   -- Display new file status (new file means no write after created)
       path = 0,                -- 0: Just the filename
                                -- 1: Relative path
                                -- 2: Absolute path
@@ -604,6 +605,7 @@ sections = {
         modified = '[+]',      -- Text to show when the file is modified.
         readonly = '[-]',      -- Text to show when the file is non-modifiable or readonly.
         unnamed = '[No Name]', -- Text to show for unnamed buffers.
+        newfile = '[New]',     -- Text to show for new created file before first writting
       }
     }
   }

lua/lualine/components/filename.lua

@@ -7,8 +7,14 @@ local modules = require('lualine_require').lazy_require {
 }
 
 local default_options = {
-  symbols = { modified = '[+]', readonly = '[-]', unnamed = '[No Name]' },
+  symbols = {
+    modified = '[+]',
+    readonly = '[-]',
+    unnamed = '[No Name]',
+    newfile = '[New]',
+  },
   file_status = true,
+  newfile_status = false,
   path = 0,
   shorting_target = 40,
 }
@@ -21,6 +27,11 @@ local function count(base, pattern)
   return select(2, string.gsub(base, pattern, ''))
 end
 
+local function is_new_file()
+  local filename = vim.fn.expand('%')
+  return vim.bo.buftype == '' and vim.fn.filereadable(filename) == 0
+end
+
 ---shortens path by turning apple/orange -> a/orange
 ---@param path string
 ---@param sep string path separator
@@ -77,6 +88,10 @@ M.update_status = function(self)
       data = data .. self.options.symbols.readonly
     end
   end
+
+  if self.options.newfile_status and is_new_file() then
+    data = data .. self.options.symbols.newfile
+  end
   return data
 end