Better comments, nerdtree settings

init.vim

@@ -1,3 +1,4 @@
+" Basic editor behavior
 set relativenumber
 set number
 set autoindent
@@ -5,29 +6,30 @@ set clipboard+=unnamed  " Use system clipboard
 set termguicolors
 set cursorline
 set ts=4 sw=4
-"gets rid of --INSERT-- useful bc of lighline"
+" Lightline already shows the current mode, so hide the default mode text.
 set noshowmode
 set mouse=a
-"splits"
+" Open new splits in the more common IDE-like directions.
 set splitright
 set splitbelow
 
+" Plugins
 call plug#begin()
-"file explorer"
+" File explorer
 Plug 'preservim/nerdtree'
-"status line"
+" Status line
 Plug 'itchyny/lightline.vim'
-"color themes"
+" Colorschemes
 Plug 'gilgigilgil/anderson.vim'
 Plug 'sainnhe/sonokai'
-"automatic parentheses"
+" Automatic bracket and quote pairing
 Plug 'jiangmiao/auto-pairs'
-"syntax highlighting"
+" Syntax highlighting and structural selection
 Plug 'nvim-treesitter/nvim-treesitter', {'do': ':TSUpdate'}
-"shortcut to comment multiple lines"
+" Commenting helpers
 Plug 'numToStr/Comment.nvim'
 
-
+" Completion and snippet support
 Plug 'neovim/nvim-lspconfig'
 Plug 'hrsh7th/cmp-nvim-lsp'
 Plug 'hrsh7th/cmp-buffer'
@@ -35,7 +37,7 @@ Plug 'hrsh7th/cmp-path'
 Plug 'hrsh7th/cmp-cmdline'
 Plug 'hrsh7th/nvim-cmp'
 
-" For vsnip users.
+" Snippet backend used by nvim-cmp
 Plug 'hrsh7th/cmp-vsnip'
 Plug 'hrsh7th/vim-vsnip'
 
@@ -43,15 +45,56 @@ call plug#end()
 
 let $NVIM_TUI_ENABLE_TRUE_COLOR=1
 
-" Start NERDTree fullscreen if no file specified, otherwise open in split
+" NERDTree startup behavior
+" - No file argument: open the tree fullscreen.
+" - File argument or stdin: open the tree on the side and return focus to the file.
+" - If the tree is the last remaining window, quit Neovim.
 autocmd StdinReadPre * let s:std_in=1
+autocmd VimEnter * call s:RegisterNERDTreeVSplitOverride()
 autocmd VimEnter * if argc() == 0 && !exists("s:std_in") | execute 'NERDTree' | only | endif
 autocmd VimEnter * if argc() > 0 || exists("s:std_in") | NERDTree | wincmd p | endif
 autocmd BufEnter * if tabpagenr('$') == 1 && winnr('$') == 1 && exists('b:NERDTree') && b:NERDTree.isTabTree() | quit | endif
 
+" Close NERDTree after opening a file from it.
+let g:NERDTreeQuitOnOpen = 1
+
+" Open a file from NERDTree in a vertical split and close the tree.
+function! NERDTreeOpenVSplitAndClose(node) abort
+    call a:node.activate({'where': 'v', 'keepopen': 0})
+endfunction
+
+" Same behavior as above, but for bookmarked nodes.
+function! NERDTreeOpenVSplitBookmarkAndClose(bookmark) abort
+    call a:bookmark.activate(b:NERDTree, !a:bookmark.path.isDirectory ? {'where': 'v', 'keepopen': 0} : {})
+endfunction
+
+" Override NERDTree's default `s` action once the plugin has been loaded.
+function! s:RegisterNERDTreeVSplitOverride() abort
+    if !exists('*NERDTreeAddKeyMap')
+        return
+    endif
+
+    call NERDTreeAddKeyMap({
+        \ 'key': 's',
+        \ 'scope': 'FileNode',
+        \ 'callback': 'NERDTreeOpenVSplitAndClose',
+        \ 'quickhelpText': 'open vsplit and close tree',
+        \ 'override': 1
+        \ })
+    call NERDTreeAddKeyMap({
+        \ 'key': 's',
+        \ 'scope': 'Bookmark',
+        \ 'callback': 'NERDTreeOpenVSplitBookmarkAndClose',
+        \ 'quickhelpText': 'open vsplit and close tree',
+        \ 'override': 1
+        \ })
+endfunction
+
+" Core NERDTree shortcuts
 nnoremap <leader>n :NERDTreeFocus<CR>
 nnoremap <C-t> :NERDTreeToggle<CR>
 let g:NERDTreeGitStatusWithFlags = 1
+" Example icon and color overrides kept here for later use.
 "let g:WebDevIconsUnicodeDecorateFolderNodes = 1
 "let g:NERDTreeGitStatusNodeColorization = 1
 "let g:NERDTreeColorMapCustom = {
@@ -67,34 +110,44 @@ let g:NERDTreeGitStatusWithFlags = 1
 
 let g:NERDTreeIgnore = ['^node_modules$']
 
+" Lightline appearance
 let g:lightline = {
       \ 'colorscheme': 'wombat',
       \ }
 
+" Colorscheme configuration
 let g:sonokai_style = 'shusia'
 let g:sonokai_better_performance = 1
 colorscheme sonokai
 
 lua << EOF
-require'nvim-treesitter.configs'.setup {
+-- Treesitter config: prefer the older `configs` entrypoint, but fall back to
-  -- Install parsers for languages you use
+-- the newer top-level module for the version currently installed locally.
-  ensure_installed = { "c", "cpp", "python", "lua", "vim", "go", "html", "css", "javascript", "ocaml"},
+local ok, ts = pcall(require, 'nvim-treesitter.configs')
+if not ok then
+  ok, ts = pcall(require, 'nvim-treesitter')
+end
 
-  -- Install all maintained parsers
+if ok then
+  ts.setup {
+    -- Parsers to install automatically.
+    ensure_installed = { "c", "cpp", "python", "lua", "vim", "go", "html", "css", "javascript", "ocaml" },
+
+    -- Install all maintained parsers instead.
     -- ensure_installed = "all",
 
-  -- Syntax highlighting
+    -- Treesitter-powered syntax highlighting.
     highlight = {
       enable = true,
       additional_vim_regex_highlighting = false,
     },
 
-  -- Indentation based on treesitter (experimental)
+    -- Treesitter indentation where supported.
     indent = {
       enable = true
     },
 
-  -- Incremental selection based on the syntax tree
+    -- Grow and shrink selections by syntax node instead of by raw text.
     incremental_selection = {
       enable = true,
       keymaps = {
@@ -104,19 +157,24 @@ require'nvim-treesitter.configs'.setup {
         node_decremental = "grm",
       },
     }
-}
+  }
+else
+  -- Keep startup working even if Treesitter is installed incorrectly.
+  vim.notify('nvim-treesitter is installed but could not be loaded', vim.log.levels.WARN)
+end
 
+-- Enable default comment mappings like gcc and gc.
 require('Comment').setup()
 EOF
 
 
 lua <<EOF
-  -- Set up nvim-cmp.
+  -- Completion setup
   local cmp = require'cmp'
 
   cmp.setup({
     snippet = {
-      -- REQUIRED - you must specify a snippet engine
+      -- nvim-cmp needs a snippet expansion function, and this config uses vsnip.
       expand = function(args)
         vim.fn["vsnip#anonymous"](args.body) -- For `vsnip` users.
         -- require('luasnip').lsp_expand(args.body) -- For `luasnip` users.
@@ -140,7 +198,14 @@ lua <<EOF
       ['<C-f>'] = cmp.mapping.scroll_docs(4),
       ['<C-Space>'] = cmp.mapping.complete(),
       ['<C-e>'] = cmp.mapping.abort(),
-      ['<CR>'] = cmp.mapping.confirm({ select = true }), -- Accept currently selected item. Set `select` to `false` to only confirm explicitly selected items.
+      -- Use Tab to confirm the current completion item, otherwise keep normal Tab behavior.
+      ['<Tab>'] = cmp.mapping(function(fallback)
+        if cmp.visible() then
+          cmp.confirm({ select = true })
+        else
+          fallback()
+        end
+      end, { 'i', 's' }),
     }),
     sources = cmp.config.sources({
       { name = 'nvim_lsp' },
@@ -153,8 +218,7 @@ lua <<EOF
     })
   })
 
-  -- To use git you need to install the plugin petertriho/cmp-git and uncomment lines below
+  -- Example git completion setup left commented out for future use.
-  -- Set configuration for specific filetype.
   --[[ cmp.setup.filetype('gitcommit', {
     sources = cmp.config.sources({
       { name = 'git' },
@@ -164,7 +228,7 @@ lua <<EOF
  })
  require("cmp_git").setup() ]]--
 
-  -- Use buffer source for `/` and `?` (if you enabled `native_menu`, this won't work anymore).
+  -- Use buffer completion while searching with `/` or `?`.
   cmp.setup.cmdline({ '/', '?' }, {
     mapping = cmp.mapping.preset.cmdline(),
     sources = {
@@ -172,7 +236,7 @@ lua <<EOF
     }
   })
 
-  -- Use cmdline & path source for ':' (if you enabled `native_menu`, this won't work anymore).
+  -- Use path and command completion for `:`.
   cmp.setup.cmdline(':', {
     mapping = cmp.mapping.preset.cmdline(),
     sources = cmp.config.sources({
@@ -183,7 +247,7 @@ lua <<EOF
     matching = { disallow_symbol_nonprefix_matching = false }
   })
 
-  -- Set up lspconfig.
+  -- Placeholder LSP wiring kept here because cmp-nvim-lsp is installed.
   local capabilities = require('cmp_nvim_lsp').default_capabilities()
   -- Replace <YOUR_LSP_SERVER> with each lsp server you've enabled.
   vim.lsp.config('<YOUR_LSP_SERVER>', {