feat: add TreePreOpen event (#3105)

* feat: Add `TreePreOpen` and `TreePreClose` events

* docs: Update docs for `TreePreOpen` and `TreePreClose` events

* chore: remove `TreePreClose` event and update dispatch of `TreePreOpen`

---------

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

doc/nvim-tree-lua.txt

@@ -2769,13 +2769,21 @@ e.g. handler for node renamed: >lua
 |nvim_tree_events_kind|
 
 - Event.Ready
-                When NvimTree has been initialized
+                When NvimTree has been initialized.
+                • Note: Handler takes no parameter.
+
+- Event.TreePreOpen
+                Invoked before the window and buffer for NvimTree are created
+                or opened. Before |Event.TreeOpen| event.
                 • Note: Handler takes no parameter.
 
 - Event.TreeOpen
+                Invoked after the NvimTree is opened.
                 • Note: Handler takes no parameter.
 
 - Event.TreeClose
+                Invoked after the NvimTree is closed, but before the window is
+                closed. Dispatched on |WinClosed| event for NvimTree window.
                 • Note: Handler takes no parameter.
 
 - Event.Resize - When NvimTree is resized.

lua/nvim-tree/events.lua

@@ -8,6 +8,7 @@ M.Event = {
   Ready = "Ready",
   WillRenameNode = "WillRenameNode",
   NodeRenamed = "NodeRenamed",
+  TreePreOpen = "TreePreOpen",
   TreeOpen = "TreeOpen",
   TreeClose = "TreeClose",
   WillCreateFile = "WillCreateFile",
@@ -91,6 +92,11 @@ function M._dispatch_folder_removed(folder_name)
   dispatch(M.Event.FolderRemoved, { folder_name = folder_name })
 end
 
+--@private
+function M._dispatch_on_tree_pre_open()
+  dispatch(M.Event.TreePreOpen, nil)
+end
+
 --@private
 function M._dispatch_on_tree_open()
   dispatch(M.Event.TreeOpen, nil)

lua/nvim-tree/view.lua

@@ -288,6 +288,7 @@ function M.open(options)
 
   local profile = log.profile_start("view open")
 
+  events._dispatch_on_tree_pre_open()
   create_buffer()
   open_window()
   M.resize()
@@ -413,6 +414,7 @@ end
 ---@param opts OpenInWinOpts|nil
 function M.open_in_win(opts)
   opts = opts or { hijack_current_buf = true, resize = true }
+  events._dispatch_on_tree_pre_open()
   if opts.winid and vim.api.nvim_win_is_valid(opts.winid) then
     vim.api.nvim_set_current_win(opts.winid)
   end