Question

In Vim, I use the standard foldmarkers {{{,}}} with a naming convention for the folds (e.g. {{{ collection). Some named folds define a comment (e.g. {{{ documentation) and I would like these to be highlighted as such. All the folds end with the same }}} marker.

I am having some success with the following:

syn region cComment start="{{{ documentation" end="}}}"
    contains=@cCommentGroup,cCommentStartError,cSpaceError,@Spell fold

but the problem is that commented folds can also contain generic collection folds, as in the following example:

{{{ documentation
    {{{ collection
    // some text
    }}}
    {{{ collection
    // some text
    }}}
}}}}

In this case, the commenting stops when the first }}} is reached, so the second collection fold is not highlighted as a comment.

The contains option does not seem relevant, as this makes contained folds have their standard highlighting.

I would like any fold inside a comment fold to inherit the comment syntax, without affecting their default syntax outside a comment fold.

Is this possible in Vim, given that all folds have the same endmarkers?

Answer 1

" Hi. Two syntax regions aren't enough, you have to use a third. There
" are two important things to note. First, 'matchgroup' (see :help
" :syn-matchgroup) prevents contained items from matching in the start
" and end patterns of the containing item. Second 'transparent' (see
" :help :syn-transparent) allows the inheriting of an item's containing
" syntax colouring.
"
" Save this entire text in a file and then :source it to see the effect.
"
"   blah
"   {{{ collection
"       blah
"   }}}
"   blah
"   {{{ documentation
"       {{{ collection
"           blah
"       }}}
"       blah
"       {{{ collection
"           blah
"       }}}
"   }}}
"   blah
"   {{{ collection
"       // some text
"   }}}
"   blah

syn clear

hi documentation guifg=darkcyan ctermfg=darkcyan
hi collection guifg=darkmagenta ctermfg=darkmagenta

syn region genericdoc start="{{{" end="}}}" transparent
syn region collection start="{{{ collection" end="}}}"
syn region documentation matchgroup=documentation
\ start="{{{ documentation" end="}}}" contains=genericdoc