How to change indentation in "case" with curly braces?

Question

The default is this:

switch(x)
{
    case a:
        {
            y();
        }
}

But I need this:

switch(x)
{
    case a:
    {
        y();
    }
}

---

With :set cindent and :set cino={-s this is the result (indentation of switch's scope is wrong this time):

int main()
{
    switch(X)
{
    case a:
    {
            //...
    }
case b:
{
        //...
}

}
}

Answer 1

You can align statements following the case label with the =N member of 'cinoptions'. The following will fix your specific example:

:set cinoptions+==0

Unfortunately, it breaks indentation if you don't use a block:

switch(x)
{
    case a:
    {
        y();
    }
    case b:
    y();
}

You've indicated in the comments that this solution works for you, though, so I'm adding it as an answer.

See this very-nearly-identical question (actually, just a more general case) for various solutions to that issue.

Answer 2

Indentation of C/C++ code is typically done by enabling the 'cindent' option (built-in to Vim), which is in turn controlled by options set in 'cinoptions'.

There are two interesting settings in 'cinoptions' that somewhat do what you want.

The first is :set cinoptions==0, which instructs Vim to not indent the block under a case statement. So you do get this effect:

case a:
{
    y();
    break;
}

On the downside, when you don't use a block starting with {, then what you get is:

case a:
y();
break;

Which looks wrong...

Then there's :set cinoptions=l1, which doesn't do exactly what you described here, but on the other hand it works well for when the { is opened on the same line as the case statement.

So you get:

case a: {
    y();
    break;
}

And if you omit the braces, then you get:

case a:
    y();
    break;

But unfortunately it doesn't help in the case where the { is opened on a line of its own, below the case statement.

These two options affect case statements exclusively, so they don't affect any other { blocks connected to any other statements (I see you found :set cino={-s but that affects the {s elsewhere.)

It's theoretically possible to get exactly what you need by writing an indentation function and setting 'indentexpr' (instead of using the built-in 'cindent'), but this would require you to write Vimscript to essentially reimplement all the built-in features of 'cindent' as well, which would surely be a herculean task... Probably best is to settle for one of the options above, or perhaps manually fix the indentation (with Ctrl+D and similar keystrokes) when you use blocks inside case statements, particularly if you don't do it too often.

Answer 3

I put together a little function that defaults to using cindent() for the indent, unless we are indenting a { line that directly follows a case statement (I've been twiddling a lot with indentexpr lately):

function s:indent(lnum, offset) abort
  return a:lnum <= 0
        \ ? indent('.')
        \ : indent(a:lnum) + a:offset
endfunction
function! c#myindentexpr(lnum) abort
  if a:lnum <= 1
    return cindent(a:lnum)
  endif
  if getline(a:lnum) =~# '^\s{' && getline(a:lnum-1) =~# '^\scase'
    return s:indent(a:lnum-1, 0)
  else
    return cindent(a:lnum)
  endif
endfunction

Drop it in ~/.vim/autoload/c.vim, and put the following line in ~/.vim/after/ftplugin/c.vim:

setlocal indentexpr=c#myindentexpr(v:lnum)

You probably want to set b:undo_ftplugin as well.

---

I tested this on a couple of simple cases and it seems to be working.