refacto: move code ton explorer and simplify some internal apis

lua/nvim-tree/explorer/init.lua

@@ -1,10 +1,47 @@
+local uv = vim.loop
+
+local git = require"nvim-tree.git"
+
 local M = {}
 
 M.explore = require"nvim-tree.explorer.explore".explore
 M.reload = require"nvim-tree.explorer.reload".reload
 
+local Explorer = {}
+Explorer.__index = Explorer
+
+function Explorer.new(cwd)
+  cwd = cwd or uv.cwd()
+  return setmetatable({
+    cwd = cwd,
+    nodes = {}
+  }, Explorer)
+end
+
+function Explorer:_load(cwd, node)
+  git.load_project_status(cwd, function(git_statuses)
+    M.explore(node, cwd, git_statuses)
+    if type(self.init_cb) == "function" then
+      self.init_cb(self)
+      self.init_cb = nil
+    end
+  end)
+end
+
+function Explorer:expand(node)
+  self.init_cb = require"nvim-tree.lib".redraw
+  self:_load(node.link_to or node.absolute_path, node)
+end
+
+function Explorer:init(f)
+  self.init_cb = f
+  self:_load(self.cwd, self)
+end
+
 function M.setup(opts)
   require"nvim-tree.explorer.utils".setup(opts)
 end
 
+M.Explorer = Explorer
+
 return M