feat(explorer): add filesystem watchers (#1304)

* feat(explorer): add experimental watchers

This commit introduces watchers to update the tree.
This behavior is introduced behind an "filesystem_watchers" option
which should prevent instabilities.
It will become the default at some point.

Co-authored-by: Alexander Courtis <alex@courtis.org>

lua/nvim-tree/explorer/init.lua

@@ -1,6 +1,7 @@
 local uv = vim.loop
 
 local git = require "nvim-tree.git"
+local watch = require "nvim-tree.explorer.watch"
 
 local M = {}
 
@@ -15,6 +16,8 @@ function Explorer.new(cwd)
   local explorer = setmetatable({
     absolute_path = cwd,
     nodes = {},
+    watcher = watch.create_watcher(cwd),
+    open = true,
   }, Explorer)
   explorer:_load(explorer)
   return explorer
@@ -30,11 +33,30 @@ function Explorer:expand(node)
   self:_load(node)
 end
 
+function Explorer.clear_watchers_for(root_node)
+  local function iterate(node)
+    if node.watcher then
+      node.watcher:stop()
+      for _, child in pairs(node.nodes) do
+        if child.watcher then
+          iterate(child)
+        end
+      end
+    end
+  end
+  iterate(root_node)
+end
+
+function Explorer:_clear_watchers()
+  Explorer.clear_watchers_for(self)
+end
+
 function M.setup(opts)
   require("nvim-tree.explorer.explore").setup(opts)
   require("nvim-tree.explorer.filters").setup(opts)
   require("nvim-tree.explorer.sorters").setup(opts)
   require("nvim-tree.explorer.reload").setup(opts)
+  require("nvim-tree.explorer.watch").setup(opts)
 end
 
 M.Explorer = Explorer

lua/nvim-tree/explorer/node-builders.lua

@@ -1,5 +1,6 @@
 local uv = vim.loop
 local utils = require "nvim-tree.utils"
+local watch = require "nvim-tree.explorer.watch"
 
 local M = {
   is_windows = vim.fn.has "win32" == 1,
@@ -18,6 +19,7 @@ function M.folder(parent, absolute_path, name)
     nodes = {},
     open = false,
     parent = parent,
+    watcher = watch.create_watcher(absolute_path),
   }
 end
 
@@ -49,12 +51,13 @@ end
 function M.link(parent, absolute_path, name)
   --- I dont know if this is needed, because in my understanding, there isnt hard links in windows, but just to be sure i changed it.
   local link_to = uv.fs_realpath(absolute_path)
-  local open, nodes, has_children
+  local open, nodes, has_children, watcher
   if (link_to ~= nil) and uv.fs_stat(link_to).type == "directory" then
     local handle = uv.fs_scandir(link_to)
     has_children = handle and uv.fs_scandir_next(handle) ~= nil
     open = false
     nodes = {}
+    watcher = watch.create_watcher(link_to)
   end
 
   return {
@@ -67,6 +70,7 @@ function M.link(parent, absolute_path, name)
     nodes = nodes,
     open = open,
     parent = parent,
+    watcher = watcher,
   }
 end
 

lua/nvim-tree/explorer/reload.lua

@@ -37,8 +37,8 @@ function M.reload(node, status)
   local node_ignored = node.git_status == "!!"
   local nodes_by_path = utils.key_by(node.nodes, "absolute_path")
   while true do
-    local name, t = uv.fs_scandir_next(handle)
-    if not name then
+    local ok, name, t = pcall(uv.fs_scandir_next, handle)
+    if not ok or not name then
       break
     end
 
@@ -48,12 +48,17 @@ function M.reload(node, status)
       child_names[abs] = true
       if not nodes_by_path[abs] then
         if t == "directory" and uv.fs_access(abs, "R") then
-          table.insert(node.nodes, builders.folder(node, abs, name))
+          local folder = builders.folder(node, abs, name)
+          nodes_by_path[abs] = folder
+          table.insert(node.nodes, folder)
         elseif t == "file" then
-          table.insert(node.nodes, builders.file(node, abs, name))
+          local file = builders.file(node, abs, name)
+          nodes_by_path[abs] = file
+          table.insert(node.nodes, file)
         elseif t == "link" then
           local link = builders.link(node, abs, name)
           if link.link_to ~= nil then
+            nodes_by_path[abs] = link
             table.insert(node.nodes, link)
           end
         end

lua/nvim-tree/explorer/watch.lua

@@ -0,0 +1,59 @@
+local log = require "nvim-tree.log"
+local utils = require "nvim-tree.utils"
+local git = require "nvim-tree.git"
+local Watcher = require("nvim-tree.watcher").Watcher
+
+local M = {}
+
+local function reload_and_get_git_project(path)
+  local project_root = git.get_project_root(path)
+  git.reload_project(project_root)
+  return project_root, git.get_project(project_root) or {}
+end
+
+local function update_parent_statuses(node, project, root)
+  while project and node and node.absolute_path ~= root do
+    require("nvim-tree.explorer.common").update_git_status(node, false, project)
+    node = node.parent
+  end
+end
+
+local function is_git(path)
+  return path:match "%.git$" ~= nil or path:match(utils.path_add_trailing ".git") ~= nil
+end
+
+function M.create_watcher(absolute_path)
+  if not M.enabled then
+    return nil
+  end
+  if is_git(absolute_path) then
+    return nil
+  end
+
+  log.line("watcher", "node start '%s'", absolute_path)
+  Watcher.new {
+    absolute_path = absolute_path,
+    interval = M.interval,
+    on_event = function(path)
+      local n = utils.get_node_from_path(absolute_path)
+      if not n then
+        return
+      end
+      log.line("watcher", "node event '%s'", path)
+
+      local node = utils.get_parent_of_group(n)
+      local project_root, project = reload_and_get_git_project(path)
+      require("nvim-tree.explorer.reload").reload(node, project)
+      update_parent_statuses(node, project, project_root)
+
+      require("nvim-tree.renderer").draw()
+    end,
+  }
+end
+
+function M.setup(opts)
+  M.enabled = opts.filesystem_watchers.enable
+  M.interval = opts.filesystem_watchers.interval
+end
+
+return M