vim: use show only leading spaces/tabs

Question

I want to use listchars (or some kind of plugin, if necessary), to make my indentation visible in vim. however, I only want the leading spaces/tabs to be visible, not all spaces and tabs.

There's a bit of a hack I discovered here for spaces. There's also an option in the comments here. The issue is that, since tabs have variable width, those options can't be used for tabs. At best, I can replace tabs with a constant width string like >---, but that means if I have a 2 character tab, the indentation ends up being off.

Is there a way to display only the leading tabs, and not the inline or trailing tabs?

Answer 1

From the VIM docs, VIM can distinguish between leading spaces and trailing spaces, but not leading tab or trailing tabs. So a tab is just a tab to VIM and is represented by tab:xy. If you define both space:c and trail:c, then the former will represent all spaces except trailing spaces, with the lateral representing trailing spaces.

                        *'listchars'* *'lcs'*
'listchars' 'lcs'   string  (default "eol:$")
            global
            {not in Vi}
    Strings to use in 'list' mode and for the |:list| command.  It is a
    comma separated list of string settings.
                            *lcs-eol*
      eol:c     Character to show at the end of each line.  When
            omitted, there is no extra character at the end of the
            line.
                            *lcs-tab*
      tab:xy    Two characters to be used to show a tab.  The first
            char is used once.  The second char is repeated to
            fill the space that the tab normally occupies.
            "tab:>-" will show a tab that takes four spaces as
            ">---".  When omitted, a tab is show as ^I.
                            *lcs-space*
      space:c   Character to show for a space.  When omitted, spaces
            are left blank.
                            *lcs-trail*
      trail:c   Character to show for trailing spaces.  When omitted,
            trailing spaces are blank.  Overrides the "space"
            setting for trailing spaces.
                            *lcs-extends*
      extends:c Character to show in the last column, when 'wrap' is
            off and the line continues beyond the right of the
            screen.
                            *lcs-precedes*
      precedes:c    Character to show in the first column, when 'wrap'
            is off and there is text preceding the character
            visible in the first column.
                            *lcs-conceal*
      conceal:c Character to show in place of concealed text, when
            'conceallevel' is set to 1.
                            *lcs-nbsp*
      nbsp:c    Character to show for a non-breakable space character
            (0xA0 (160 decimal) and U+202F).  Left blank when
            omitted.

    The characters ':' and ',' should not be used.  UTF-8 characters can
    be used when 'encoding' is "utf-8", otherwise only printable
    characters are allowed.  All characters must be single width.

    Examples: >
        :set lcs=tab:>-,trail:-
        :set lcs=tab:>-,eol:<,nbsp:%
        :set lcs=extends:>,precedes:<
<   The "NonText" highlighting will be used for "eol", "extends" and
    "precedes".  "SpecialKey" for "nbsp", "space", "tab" and "trail".
    |hl-NonText| |hl-SpecialKey|

A better approach might be to use match with syntax, something like::

highlight LeadingSpace ctermbg=red guibg=red
highlight TrailingSpace ctermbg=red guibg=red
highlight LeadingTab ctermbg=red guibg=green
highlight TrailingTab ctermbg=red guibg=green
call matchadd('LeadingSpace', '^\s\+', 80)
call matchadd('TrailingSpace', '\s\+$', 80)
call matchadd('LeadingTab', '^t\+', 99)    
call matchadd('TrailingTab', '\t\+$', 99)