Auto indenting fails when using the "cc", "S", or "]p" commands on a blank line in Vim

Question

If I try cc or S when the cursor (| below) is in the following position:

public function blah()
{
    var i = 0;
|
    i++
    return i;
}

It stays in the first column instead of moving under the letter v in var. Pasting with ]p also pastes starting from column 1.

My setup (in MacVim) is: autoindent, smartindent, nocindent, and indentexpr=, if that helps.

According to the following SO questions, correct indentation should be possible:

• Vim: Smart indent when entering insert mode on blank line?
• Vim: Indent current (blank) line and insert
• Autoindent in vim always empty the line if there are only whitespace in it, can I change that?

In the last post, @trVoldemort had the same issue (see the comments to the second answer).

Answer 1

From the manual:

                            *cc*
["x]cc          Delete [count] lines [into register x] and start
                insert |linewise|.  If 'autoindent' is on, preserve
                the indent of the first line.

                            *S*
["x]S           Delete [count] lines [into register x] and start
                insert.  Synonym for "cc" |linewise|.

Since the line you are deleting has no indent, that indent is preserved. If you insert spaces in that line, so that $ puts your cursor here:

public function blah() {
    var i = 0;
    |
    i++
    return i;
}

then press 0 to go back to the first column, and finally press S, you'll get the desired result.

I realize this only explains the current behavior but does not directly solve your problem, but I am unsure of a clean way to solve your issue. I'd be inclined to suggested doing a mapping like this:

:nnoremap cc ddko
:nnoremap S ddko

These dd delete the current line, k move up to the previous line, o open input on the following line (using smartindent to supply the indentation).

Answer 2

Turn on cindent...

:set cindent

This works for indenting with "cc" and "S", as long as the language has similar indentation to C (or support for cindent).

With this, the smart-indent paste (]p) still doesn't work on an empty line, however. For that, remap ]p as follows:

:nnoremap ]p oX<Esc>]pk"_dd

This will create a new line at the correct indentation before doing the re-indent paste. Then it goes back and deletes that line, making sure not to overwrite the default buffer.

You can also remap the alternative versions of the smart-indent paste:

:nnoremap ]P OX<Esc>]pk"_dd
:vnoremap ]p "_xkoX<Esc>]pk"_dd
:vnoremap ]P "_xkoX<Esc>]pk"_dd

Answer 3

One can explicitly auto-indent lines before applying the cc, S, or ]p Normal-mode command, as shown in the following mappings.

:nnoremap <leader>cc i.<esc>==S
:nnoremap <leader>]p ]p`[v`]=

Generally speaking, the effect of the = and == commands is not exactly the same as the effect of the autoindent option has on the cc or ]p commands (especially in case of a custom equalprg), but resulting behavior seems to, nevertheless, match your description.

Answer 4

When I use :filetype indent on, pressing cc on that line indents it properly.