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.

5 files changed, 184 insertions, 158 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
diff --git a/runtime/lua/vim/_editor.lua b/runtime/lua/vim/_editor.lua
index 0bdf0c90a5..98a1ce79ed 100644
--- a/runtime/lua/vim/_editor.lua
+++ b/runtime/lua/vim/_editor.lua
@@ -1031,156 +1031,6 @@ function vim.deprecate(name, alternative, version, plugin, backtrace)
   return displayed and msg or nil
 end
 
---- Creates builtin mappings (incl. menus).
---- Called once on startup.
-function vim._init_default_mappings()
-  -- mappings
-
-  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
-
-  local function map(mode, lhs, rhs)
-    vim.keymap.set(mode, lhs, rhs, { desc = 'Nvim builtin' })
-  end
-
-  map('n', 'Y', 'y$')
-  -- Use normal! <C-L> to prevent inserting raw <C-L> when using i_<C-O>. #17473
-  map('n', '<C-L>', '<Cmd>nohlsearch<Bar>diffupdate<Bar>normal! <C-L><CR>')
-  map('i', '<C-U>', '<C-G>u<C-U>')
-  map('i', '<C-W>', '<C-G>u<C-W>')
-  vim.keymap.set('x', '*', function()
-    return _visual_search('/')
-  end, { desc = ':help v_star-default', expr = true, silent = true })
-  vim.keymap.set('x', '#', function()
-    return _visual_search('?')
-  end, { desc = ':help v_#-default', expr = true, silent = true })
-  -- Use : instead of <Cmd> so that ranges are supported. #19365
-  map('n', '&', ':&&<CR>')
-
-  -- gx
-
-  -- TODO: use vim.region() when it lands... #13896 #16843
-  local function get_visual_selection()
-    local save_a = vim.fn.getreginfo('a')
-    vim.cmd([[norm! "ay]])
-    local selection = vim.fn.getreg('a', 1)
-    vim.fn.setreg('a', save_a)
-    return selection
-  end
-
-  local function do_open(uri)
-    local _, err = vim.ui.open(uri)
-    if err then
-      vim.notify(err, vim.log.levels.ERROR)
-    end
-  end
-
-  local gx_desc =
-    'Opens filepath or URI under cursor with the system handler (file explorer, web browser, …)'
-  vim.keymap.set({ 'n' }, 'gx', function()
-    do_open(vim.fn.expand('<cfile>'))
-  end, { desc = gx_desc })
-  vim.keymap.set({ 'x' }, 'gx', function()
-    do_open(get_visual_selection())
-  end, { desc = gx_desc })
-
-  -- menus
-
-  -- TODO VimScript, no l10n
-  vim.cmd([[
-    aunmenu *
-    vnoremenu PopUp.Cut                     "+x
-    vnoremenu PopUp.Copy                    "+y
-    anoremenu PopUp.Paste                   "+gP
-    vnoremenu PopUp.Paste                   "+P
-    vnoremenu PopUp.Delete                  "_x
-    nnoremenu PopUp.Select\ All             ggVG
-    vnoremenu PopUp.Select\ All             gg0oG$
-    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
-
-function vim._init_default_autocmds()
-  local nvim_terminal_augroup = vim.api.nvim_create_augroup('nvim_terminal', {})
-  vim.api.nvim_create_autocmd({ 'BufReadCmd' }, {
-    pattern = 'term://*',
-    group = nvim_terminal_augroup,
-    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 = '[:>]',
-    group = vim.api.nvim_create_augroup('nvim_cmdwin', {}),
-    command = 'syntax sync minlines=1 maxlines=1',
-  })
-
-  vim.api.nvim_create_autocmd({ 'SwapExists' }, {
-    pattern = '*',
-    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
-
-function vim._init_defaults()
-  vim._init_default_mappings()
-  vim._init_default_autocmds()
-end
-
 require('vim._options')
 
 -- Remove at Nvim 1.0
diff --git a/src/nvim/CMakeLists.txt b/src/nvim/CMakeLists.txt
index e881214f40..cc5fb25b1e 100644
--- a/src/nvim/CMakeLists.txt
+++ b/src/nvim/CMakeLists.txt
@@ -290,6 +290,7 @@ set(LUA_LOADER_MODULE_SOURCE ${NVIM_RUNTIME_DIR}/lua/vim/loader.lua)
 set(LUA_INSPECT_MODULE_SOURCE ${NVIM_RUNTIME_DIR}/lua/vim/inspect.lua)
 set(LUA_FS_MODULE_SOURCE ${NVIM_RUNTIME_DIR}/lua/vim/fs.lua)
 set(LUA_F_MODULE_SOURCE ${NVIM_RUNTIME_DIR}/lua/vim/F.lua)
+set(LUA_DEFAULTS_MODULE_SOURCE ${NVIM_RUNTIME_DIR}/lua/vim/_defaults.lua)
 set(LUA_OPTIONS_MODULE_SOURCE ${NVIM_RUNTIME_DIR}/lua/vim/_options.lua)
 set(LUA_FILETYPE_MODULE_SOURCE ${NVIM_RUNTIME_DIR}/lua/vim/filetype.lua)
 set(LUA_INIT_PACKAGES_MODULE_SOURCE ${NVIM_RUNTIME_DIR}/lua/vim/_init_packages.lua)
@@ -535,6 +536,7 @@ add_custom_command(
       ${LUA_F_MODULE_SOURCE} "vim.F"
       ${LUA_KEYMAP_MODULE_SOURCE} "vim.keymap"
       ${LUA_LOADER_MODULE_SOURCE} "vim.loader"
+      ${LUA_DEFAULTS_MODULE_SOURCE} "vim._defaults"
       ${LUA_OPTIONS_MODULE_SOURCE} "vim._options"
       ${LUA_SHARED_MODULE_SOURCE} "vim.shared"
   DEPENDS
@@ -547,6 +549,7 @@ add_custom_command(
     ${LUA_F_MODULE_SOURCE}
     ${LUA_KEYMAP_MODULE_SOURCE}
     ${LUA_LOADER_MODULE_SOURCE}
+    ${LUA_DEFAULTS_MODULE_SOURCE}
     ${LUA_OPTIONS_MODULE_SOURCE}
     ${LUA_SHARED_MODULE_SOURCE}
   VERBATIM
diff --git a/src/nvim/lua/executor.c b/src/nvim/lua/executor.c
index b389f33d8d..36cb8a6756 100644
--- a/src/nvim/lua/executor.c
+++ b/src/nvim/lua/executor.c
@@ -2291,3 +2291,17 @@ plain:
   kv_printf(str, "<Lua %d>", ref);
   return str.items;
 }
+
+/// Execute the vim._defaults module to set up default mappings and autocommands
+void nlua_init_defaults(void)
+{
+  lua_State *const L = global_lstate;
+  assert(L);
+
+  lua_getglobal(L, "require");
+  lua_pushstring(L, "vim._defaults");
+  if (nlua_pcall(L, 1, 0)) {
+    os_errmsg(lua_tostring(L, -1));
+    os_errmsg("\n");
+  }
+}
diff --git a/src/nvim/main.c b/src/nvim/main.c
index 433b735c2e..42c98ead66 100644
--- a/src/nvim/main.c
+++ b/src/nvim/main.c
@@ -413,14 +413,7 @@ int main(int argc, char **argv)
 
   open_script_files(&params);
 
-  // Default mappings (incl. menus) & autocommands
-  Error err = ERROR_INIT;
-  Object o = NLUA_EXEC_STATIC("return vim._init_defaults()",
-                              (Array)ARRAY_DICT_INIT, &err);
-  assert(!ERROR_SET(&err));
-  api_clear_error(&err);
-  assert(o.type == kObjectTypeNil);
-  api_free_object(o);
+  nlua_init_defaults();
 
   TIME_MSG("init default mappings & autocommands");