Question

I m putting together a syntax for editing Java Manifest files (at github, if anyone s interested). I m trying to collapse multiple single-line-comments (which I m matching at the moment with syntax match manifestComment "#.*"). However, if I try to use a syntax region, then the entire file is marked and the entire thing collapses.

What I m trying to achieve is this:

# A comment
# Another comment
# A third comment
Manifest-Version: 1

and have it collapse down into:

+--  3 lines: # A comment ----
Manifest-Version: 1

The problem is that there s no distinct end character, and the fold syntax doesn t help; so I can t do syntax region commentBlock start="^#" end="^[^#]". Roughly, the syntax region should start from the first hash character, and then continue down the lines until it finds a line which doesn t begin with a hash.

Answer 1

:set foldmethod=expr
:set foldexpr=getline(v:lnum)[0]=="#"

For information, :h fold-expr.

Answer 2

How about syntax region commentBlock start="^#" end="^#@!"?

The @! is like (?!pattern) in Perl, i.e. it matches with zero-width if the preceding atom -- # in this case -- does not match at the current position.

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