feat: Help UI for keybindings (#470)

lua/nvim-tree.lua

@@ -68,6 +68,7 @@ local keypress_funcs = {
   parent_node = lib.parent_node,
   toggle_ignored = lib.toggle_ignored,
   toggle_dotfiles = lib.toggle_dotfiles,
+  toggle_help = lib.toggle_help,
   refresh = lib.refresh_tree,
   first_sibling = function(node) lib.sibling(node, -math.huge) end,
   last_sibling = function(node) lib.sibling(node, math.huge) end,
@@ -84,6 +85,7 @@ local keypress_funcs = {
 }
 
 function M.on_keypress(mode)
+  if view.is_help_ui() and mode ~= 'toggle_help' then return end
   local node = lib.get_node_at_cursor()
   if not node then return end
 

lua/nvim-tree/lib.lua

@@ -95,14 +95,20 @@ end
 function M.get_node_at_cursor()
   local cursor = api.nvim_win_get_cursor(view.get_winnr())
   local line = cursor[1]
-  if line == 1 and M.Tree.cwd ~= "/" then
-    return { name = ".." }
-  end
+  if view.is_help_ui() then
+    local help_lines, _ = renderer.draw_help()
+    local help_text = get_node_at_line(line+1)(help_lines)
+    return {name = help_text}
+  else
+    if line == 1 and M.Tree.cwd ~= "/" then
+      return { name = ".." }
+    end
 
-  if M.Tree.cwd == "/" then
-    line = line + 1
+    if M.Tree.cwd == "/" then
+      line = line + 1
+    end
+    return get_node_at_line(line)(M.Tree.entries)
   end
-  return get_node_at_line(line)(M.Tree.entries)
 end
 
 -- If node is grouped, return the last node in the group. Otherwise, return the given node.
@@ -223,7 +229,7 @@ end
 function M.pick_window()
   local tabpage = api.nvim_get_current_tabpage()
   local win_ids = api.nvim_tabpage_list_wins(tabpage)
-  local tree_winid = view.View.tabpages[tabpage]
+  local tree_winid = view.get_winnr(tabpage)
   local exclude = config.window_picker_exclude()
 
   local selectable = vim.tbl_filter(function (id)
@@ -423,7 +429,7 @@ end
 
 function M.set_target_win()
   local id = api.nvim_get_current_win()
-  local tree_id = view.View.tabpages[api.nvim_get_current_tabpage()]
+  local tree_id = view.get_winnr()
   if tree_id and id == tree_id then
     M.Tree.target_winid = 0
     return
@@ -517,6 +523,11 @@ function M.toggle_dotfiles()
   return M.refresh_tree()
 end
 
+function M.toggle_help()
+  view.toggle_help()
+  return M.refresh_tree()
+end
+
 function M.dir_up(node)
   if not node or node.name == ".." then
     return M.change_dir('..')

lua/nvim-tree/renderer.lua

@@ -366,6 +366,40 @@ end
 
 local M = {}
 
+function M.draw_help()
+    local help_lines = {'HELP'}
+    local help_hl = {{'NvimTreeRootFolder', 0, 0, string.len('HELP')}}
+    local bindings = view.View.bindings
+    local processed = {}
+    for i, v in pairs(bindings) do
+      if v:sub(1,35) == view.nvim_tree_callback('test'):sub(1,35) then
+        v = v:match("'[^']+'[^']*$")
+        v = v:match("'[^']+'")
+        table.insert(processed,{i,v,true})
+      else
+        v = '"' .. v .. '"'
+        table.insert(processed,{i,v,false})
+      end
+    end
+    table.sort(processed,function(a,b)
+      return (a[3]==b[3] and (a[2]<b[2] or (a[2]==b[2] and #a[1]<#b[1]))) or (a[3] and not b[3])
+    end)
+    local i, v, builtin
+    for num, val in pairs(processed) do
+      i = val[1]
+      v = val[2]
+      builtin = val[3]
+      local bind_string = string.format("%6s : %s",i,v)
+      table.insert(help_lines,bind_string)
+      local hl_len = math.max(6,#i)+2
+      table.insert(help_hl,{'NvimTreeFolderName', num, 0, hl_len})
+      if not builtin then
+        table.insert(help_hl,{'NvimTreeFileRenamed', num, hl_len, -1})
+      end
+    end
+    return help_lines, help_hl
+end
+
 function M.draw(tree, reload)
   if not api.nvim_buf_is_loaded(view.View.bufnr) then return end
   local cursor
@@ -381,6 +415,9 @@ function M.draw(tree, reload)
     update_draw_data(tree, show_arrows and 2 or 0, {})
   end
 
+  if view.is_help_ui() then
+    lines, hl = M.draw_help()
+  end
   api.nvim_buf_set_option(view.View.bufnr, 'modifiable', true)
   api.nvim_buf_set_lines(view.View.bufnr, 0, -1, false, lines)
   M.render_hl(view.View.bufnr)

lua/nvim-tree/view.lua

@@ -75,6 +75,7 @@ M.View = {
     ["]c"]             = M.nvim_tree_callback("next_git_item"),
     ["-"]              = M.nvim_tree_callback("dir_up"),
     ["q"]              = M.nvim_tree_callback("close"),
+    ["?"]              = M.nvim_tree_callback("toggle_help")
   }
 }
 
@@ -171,7 +172,7 @@ end
 function M.win_open(opts)
   if opts and opts.any_tabpage then
     for _, v in pairs(M.View.tabpages) do
-      if  a.nvim_win_is_valid(v) then
+      if a.nvim_win_is_valid(v.winnr) then
         return true
       end
     end
@@ -226,7 +227,8 @@ function M.open()
   a.nvim_command("wincmd "..move_to)
   a.nvim_command("vertical resize "..M.View.width)
   local winnr = a.nvim_get_current_win()
-  M.View.tabpages[a.nvim_get_current_tabpage()] = winnr
+  local tabpage = a.nvim_get_current_tabpage()
+  M.View.tabpages[tabpage] = vim.tbl_extend("force", M.View.tabpages[tabpage] or {help = false}, {winnr = winnr})
   for k, v in pairs(M.View.winopts) do
     vim.wo[winnr][k] = v
   end
@@ -249,8 +251,31 @@ function M.close()
   a.nvim_win_hide(M.get_winnr())
 end
 
-function M.get_winnr()
-  return M.View.tabpages[a.nvim_get_current_tabpage()]
+--- Returns the window number for nvim-tree within the tabpage specified
+---@param tabpage number: (optional) the number of the chosen tabpage. Defaults to current tabpage.
+---@return number
+function M.get_winnr(tabpage)
+  tabpage = tabpage or a.nvim_get_current_tabpage()
+  local tabinfo = M.View.tabpages[tabpage]
+  if tabinfo ~= nil then
+    return tabinfo.winnr
+  end
+end
+
+--- Checks if nvim-tree is displaying the help ui within the tabpage specified
+---@param tabpage number: (optional) the number of the chosen tabpage. Defaults to current tabpage.
+---@return number
+function M.is_help_ui(tabpage)
+  tabpage = tabpage or a.nvim_get_current_tabpage()
+  local tabinfo = M.View.tabpages[tabpage]
+  if tabinfo ~= nil then
+    return tabinfo.help
+  end
+end
+
+function M.toggle_help(tabpage)
+  tabpage = tabpage or a.nvim_get_current_tabpage()
+  M.View.tabpages[tabpage].help = not M.View.tabpages[tabpage].help
 end
 
 return M