refactor(defaults): use vim.region for visual star (*,#)

Problem:
The parent commit added a new vim.get_visual_selection() function to
improve visual star. But that is redundant with vim.region(). Any
current limitations of vim.region() should be fixed instead of adding
a new function.

Solution:
Delete vim.get_visual_selection().
Use vim.region() to get the visual selection.
TODO: fails with visual "block" selections.

runtime/doc/lua.txt

@@ -1408,26 +1408,7 @@ deprecate({name}, {alternative}, {version}, {plugin}, {backtrace})
       • {backtrace}    boolean|nil Prints backtrace. Defaults to true.
 
     Return: ~
-        Deprecated message, or nil if no message was shown.
-
-                                                  *vim.get_visual_selection()*
-get_visual_selection({list}, {append_empty})
-    Gets the content of the visual selection.
-
-    The result is either a string or, if {list} is `true`, a list of strings.
-    If not in any |visual-mode|, `nil` is returned.
-
-    Parameters: ~
-      • {list}          boolean|nil Return a list of strings instead of a
-                        string. See |getreg()|. Defaults to `false`.
-      • {append_empty}  boolean|nil Append an empty string to the result when
-                        in |linewise-visual| mode and {list} is `true`. This
-                        will preserve the trailing newline of the selection
-                        when the result is concatenated with `"\n"`. Defaults
-                        to `false`.
-
-    Return: ~
-        string|table
+        (string|nil) # Deprecated message, or nil if no message was shown.
 
 inspect({object}, {options})                                   *vim.inspect()*
     Gets a human-readable representation of the given object.

runtime/doc/vim_diff.txt

@@ -114,15 +114,14 @@ DEFAULT MAPPINGS
 							*default-mappings*
 Nvim creates the following default mappings at |startup|. You can disable any
 of these in your config by simply removing the mapping, e.g. ":unmap Y".
->vim
-	nnoremap Y y$
-	nnoremap <C-L> <Cmd>nohlsearch<Bar>diffupdate<Bar>normal! <C-L><CR>
-	inoremap <C-U> <C-G>u<C-U>
-	inoremap <C-W> <C-G>u<C-W>
-	nnoremap & :&&<CR>
-<
-Default mappings composed of Lua code are not listed above. Use ":map" to see
-the |map-listing|.
+
+- |Y-default|
+- |i_CTRL-U-default|
+- |i_CTRL-W-default|
+- |CTRL-L-default|
+- |&-default|
+- |v_#-default|
+- |v_star-default|
 
 DEFAULT AUTOCOMMANDS
 							*default-autocmds*

runtime/lua/vim/_editor.lua

@@ -535,55 +535,6 @@ function vim.region(bufnr, pos1, pos2, regtype, inclusive)
   return region
 end
 
---- Gets the content of the visual selection.
----
---- The result is either a string or, if {list} is `true`, a list of strings.
---- If not in any |visual-mode|, `nil` is returned.
----
---- @param list boolean|nil
----        Return a list of strings instead of a string.  See |getreg()|.
----        Defaults to `false`.
---- @param append_empty boolean|nil
----        Append an empty string to the result when in |linewise-visual| mode and {list} is `true`.
----        This will preserve the trailing newline of the selection when the result is concatenated with `"\n"`.
----        Defaults to `false`.
---- @return string|table
-function vim.get_visual_selection(list, append_empty)
-  list = list or false
-  append_empty = append_empty or false
-
-  local mode = vim.api.nvim_get_mode().mode
-  if mode ~= 'v' and mode ~= 'V' and mode:byte() ~= 22 then
-    return nil
-  end
-
-  local reg_name_unnamed = '"'
-  local reg_name_yank = '0'
-
-  local reg_info_unnamed = vim.fn.getreginfo(reg_name_unnamed)
-  local reg_info_yank = vim.fn.getreginfo(reg_name_yank)
-  local opt_clipboard = vim.o.clipboard
-  local opt_report = vim.o.report
-
-  vim.o.clipboard = ''
-  vim.o.report = vim.v.maxcol
-
-  vim.api.nvim_feedkeys('y', 'nx', false)
-
-  local yanked = vim.fn.getreg(reg_name_yank, 1, list)
-
-  vim.fn.setreg(reg_name_unnamed, reg_info_unnamed)
-  vim.fn.setreg(reg_name_yank, reg_info_yank)
-  vim.o.clipboard = opt_clipboard
-  vim.o.report = opt_report
-
-  if list and append_empty and mode == 'V' then
-    table.insert(yanked, '')
-  end
-
-  return yanked
-end
-
 --- Defers calling {fn} until {timeout} ms passes.
 ---
 --- Use to do a one-shot timer that calls {fn}
@@ -1034,7 +985,7 @@ end
 ---                              Defaults to "Nvim".
 ---@param backtrace   boolean|nil Prints backtrace. Defaults to true.
 ---
----@return Deprecated message, or nil if no message was shown.
+---@return string|nil # Deprecated message, or nil if no message was shown.
 function vim.deprecate(name, alternative, version, plugin, backtrace)
   local msg = ('%s is deprecated'):format(name)
   plugin = plugin or 'Nvim'
@@ -1049,9 +1000,7 @@ function vim.deprecate(name, alternative, version, plugin, backtrace)
   if displayed and backtrace ~= false then
     vim.notify(debug.traceback('', 2):sub(2), vim.log.levels.WARN)
   end
-  if displayed then
-    return msg
-  end
+  return displayed and msg or nil
 end
 
 --- Create builtin mappings (incl. menus).
@@ -1060,27 +1009,37 @@ function vim._init_default_mappings()
   -- mappings
 
   ---@private
-  local function _search_for_visual_selection(search_prefix)
-    if search_prefix ~= '/' and search_prefix ~= '?' then
-      return
+  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
-    -- Escape these characters
-    local replacements = {
-      [search_prefix] = [[\]] .. search_prefix,
-      [ [[\]] ] = [[\\]],
-      ['\t'] = [[\t]],
-      ['\n'] = [[\n]],
-    }
-    local pattern = '[' .. table.concat(vim.tbl_keys(replacements), '') .. ']'
-    local visual_selection = vim.get_visual_selection(false)
-    local escaped_visual_selection = string.gsub(visual_selection, pattern, replacements)
-    local search_cmd = search_prefix .. [[\V]] .. escaped_visual_selection .. '\n'
+    return chunks
+  end
+
+  ---@private
+  local function _visual_search(cmd)
+    assert(cmd == '/' or cmd == '?')
+    vim.api.nvim_feedkeys('\27', 'nx', true) -- Escape visual mode.
+    local region = vim.region(0, "'<", "'>", vim.fn.visualmode(), vim.o.selection == 'inclusive')
+    local chunks = region_chunks(region)
+    local esc_chunks = vim
+      .iter(chunks)
+      :map(function(v)
+        return vim.fn.escape(v, [[/\]])
+      end)
+      :totable()
+    local esc_pat = table.concat(esc_chunks, [[\n]])
+    local search_cmd = ([[%s\V%s%s]]):format(cmd, esc_pat, '\n')
     vim.api.nvim_feedkeys(search_cmd, 'nx', true)
   end
 
   ---@private
   local function map(mode, lhs, rhs)
-    vim.keymap.set(mode, lhs, rhs, { noremap = true, desc = 'Nvim builtin' })
+    vim.keymap.set(mode, lhs, rhs, { desc = 'Nvim builtin' })
   end
 
   map('n', 'Y', 'y$')
@@ -1088,12 +1047,12 @@ function vim._init_default_mappings()
   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>')
-  map('x', '*', function()
-    _search_for_visual_selection('/')
-  end)
-  map('x', '#', function()
-    _search_for_visual_selection('?')
-  end)
+  vim.keymap.set('x', '*', function()
+    _visual_search('/')
+  end, { desc = 'Nvim builtin', silent = true })
+  vim.keymap.set('x', '#', function()
+    _visual_search('?')
+  end, { desc = 'Nvim builtin', silent = true })
   -- Use : instead of <Cmd> so that ranges are supported. #19365
   map('n', '&', ':&&<CR>')