refactor: move defaults into separate module (#25929)

Move default mappings and autocommands into a separate module and add
comments and docstrings to document each of the defaults.

1 files changed, 166 insertions, 0 deletions

diff --git a/runtime/lua/vim/_defaults.lua b/runtime/lua/vim/_defaults.lua
new file mode 100644
index 0000000000..c1b50e6950
--- /dev/null
+++ b/runtime/lua/vim/_defaults.lua
@@ -0,0 +1,166 @@
+--- Default mappings
+do
+  --- Default maps for * and # in visual mode.
+  ---
+  --- See |v_star-default| and |v_#-default|
+  do
+    local function region_chunks(region)
+      local chunks = {}
+      local maxcol = vim.v.maxcol
+      for line, cols in vim.spairs(region) do
+        local endcol = cols[2] == maxcol and -1 or cols[2]
+        local chunk = vim.api.nvim_buf_get_text(0, line, cols[1], line, endcol, {})[1]
+        table.insert(chunks, chunk)
+      end
+      return chunks
+    end
+
+    local function _visual_search(cmd)
+      assert(cmd == '/' or cmd == '?')
+      local region = vim.region(
+        0,
+        '.',
+        'v',
+        vim.api.nvim_get_mode().mode:sub(1, 1),
+        vim.o.selection == 'inclusive'
+      )
+      local chunks = region_chunks(region)
+      local esc_chunks = vim
+        .iter(chunks)
+        :map(function(v)
+          return vim.fn.escape(v, cmd == '/' and [[/\]] or [[?\]])
+        end)
+        :totable()
+      local esc_pat = table.concat(esc_chunks, [[\n]])
+      local search_cmd = ([[%s\V%s%s]]):format(cmd, esc_pat, '\n')
+      return '\27' .. search_cmd
+    end
+
+    vim.keymap.set('x', '*', function()
+      return _visual_search('/')
+    end, { desc = ':help v_star-default', expr = true, silent = true })
+    vim.keymap.set('x', '#', function()
+      return _visual_search('?')
+    end, { desc = ':help v_#-default', expr = true, silent = true })
+  end
+
+  --- Map Y to y$. This mimics the behavior of D and C. See |Y-default|
+  vim.keymap.set('n', 'Y', 'y$', { desc = ':help Y-default' })
+
+  --- Use normal! <C-L> to prevent inserting raw <C-L> when using i_<C-O>. #17473
+  ---
+  --- See |CTRL-L-default|
+  vim.keymap.set('n', '<C-L>', '<Cmd>nohlsearch<Bar>diffupdate<Bar>normal! <C-L><CR>', {
+    desc = ':help CTRL-L-default',
+  })
+
+  --- Set undo points when deleting text in insert mode.
+  ---
+  --- See |i_CTRL-U-default| and |i_CTRL-W-default|
+  vim.keymap.set('i', '<C-U>', '<C-G>u<C-U>', { desc = ':help i_CTRL-U-default' })
+  vim.keymap.set('i', '<C-W>', '<C-G>u<C-W>', { desc = ':help i_CTRL-W-default' })
+
+  --- Use the same flags as the previous substitution with &.
+  ---
+  --- Use : instead of <Cmd> so that ranges are supported. #19365
+  ---
+  --- See |&-default|
+  vim.keymap.set('n', '&', ':&&<CR>', { desc = ':help &-default' })
+
+  --- Map |gx| to call |vim.ui.open| on the identifier under the cursor
+  do
+    -- TODO: use vim.region() when it lands... #13896 #16843
+    local function get_visual_selection()
+      local save_a = vim.fn.getreginfo('a')
+      vim.cmd([[norm! "ay]])
+      local selection = vim.fn.getreg('a', 1)
+      vim.fn.setreg('a', save_a)
+      return selection
+    end
+
+    local function do_open(uri)
+      local _, err = vim.ui.open(uri)
+      if err then
+        vim.notify(err, vim.log.levels.ERROR)
+      end
+    end
+
+    local gx_desc =
+      'Opens filepath or URI under cursor with the system handler (file explorer, web browser, …)'
+    vim.keymap.set({ 'n' }, 'gx', function()
+      do_open(vim.fn.expand('<cfile>'))
+    end, { desc = gx_desc })
+    vim.keymap.set({ 'x' }, 'gx', function()
+      do_open(get_visual_selection())
+    end, { desc = gx_desc })
+  end
+end
+
+--- Default menus
+do
+  --- Right click popup menu
+  -- TODO VimScript, no l10n
+  vim.cmd([[
+    aunmenu *
+    vnoremenu PopUp.Cut                     "+x
+    vnoremenu PopUp.Copy                    "+y
+    anoremenu PopUp.Paste                   "+gP
+    vnoremenu PopUp.Paste                   "+P
+    vnoremenu PopUp.Delete                  "_x
+    nnoremenu PopUp.Select\ All             ggVG
+    vnoremenu PopUp.Select\ All             gg0oG$
+    inoremenu PopUp.Select\ All             <C-Home><C-O>VG
+    anoremenu PopUp.-1-                     <Nop>
+    anoremenu PopUp.How-to\ disable\ mouse  <Cmd>help disable-mouse<CR>
+  ]])
+end
+
+--- Default autocommands. See |default-autocmds|
+do
+  local nvim_terminal_augroup = vim.api.nvim_create_augroup('nvim_terminal', {})
+  vim.api.nvim_create_autocmd('BufReadCmd', {
+    pattern = 'term://*',
+    group = nvim_terminal_augroup,
+    desc = 'Treat term:// buffers as terminal buffers',
+    nested = true,
+    command = "if !exists('b:term_title')|call termopen(matchstr(expand(\"<amatch>\"), '\\c\\mterm://\\%(.\\{-}//\\%(\\d\\+:\\)\\?\\)\\?\\zs.*'), {'cwd': expand(get(matchlist(expand(\"<amatch>\"), '\\c\\mterm://\\(.\\{-}\\)//'), 1, ''))})",
+  })
+
+  vim.api.nvim_create_autocmd({ 'TermClose' }, {
+    group = nvim_terminal_augroup,
+    desc = 'Automatically close terminal buffers when started with no arguments and exiting without an error',
+    callback = function(args)
+      if vim.v.event.status == 0 then
+        local info = vim.api.nvim_get_chan_info(vim.bo[args.buf].channel)
+        local argv = info.argv or {}
+        if #argv == 1 and argv[1] == vim.o.shell then
+          vim.cmd({ cmd = 'bdelete', args = { args.buf }, bang = true })
+        end
+      end
+    end,
+  })
+
+  vim.api.nvim_create_autocmd('CmdwinEnter', {
+    pattern = '[:>]',
+    desc = 'Limit syntax sync to maxlines=1 in the command window',
+    group = vim.api.nvim_create_augroup('nvim_cmdwin', {}),
+    command = 'syntax sync minlines=1 maxlines=1',
+  })
+
+  vim.api.nvim_create_autocmd('SwapExists', {
+    pattern = '*',
+    desc = 'Skip the swapfile prompt when the swapfile is owned by a running Nvim process',
+    group = vim.api.nvim_create_augroup('nvim_swapfile', {}),
+    callback = function()
+      local info = vim.fn.swapinfo(vim.v.swapname)
+      local user = vim.uv.os_get_passwd().username
+      local iswin = 1 == vim.fn.has('win32')
+      if info.error or info.pid <= 0 or (not iswin and info.user ~= user) then
+        vim.v.swapchoice = '' -- Show the prompt.
+        return
+      end
+      vim.v.swapchoice = 'e' -- Choose "(E)dit".
+      vim.notify(('W325: Ignoring swapfile from Nvim process %d'):format(info.pid))
+    end,
+  })
+end