How to fold C++-style comments in Vim?

Question

Syntax folding in Vim makes it easy to create folds for regions, the start and end of which can be defined with regular expressions:

syn region myRegion start="#region" end="#endregion" transparent keepend extend fold

However, I am not sure how I can use syntax folding to define folds for C++-style comments, which are sets of lines beginning with "//".

Answer 1

I was trying to do something like:

syn region myCComment start="^\s*\/\/" end="$" contains=myCComment fold

But that won't work as it will not properly close the fold. I'm afraid the only way to do this is by writing a vim script function that's smart enough to match multiple // lines in a row. I might do this when I have some spare time.

Answer 2

Why do you need to fold comments starting with "//" ? Those are one-line comments and they should be minimalistic and short so they don't need to be folded. You should fold only comment blocks starting with "/*" and ending with "*/" and that should be easy to implement.

According to your post this should be valid:

syn region CommentBlock start="/*" end="*/" transparent keepend extend fold

Answer 3

I think I found a solution:

:syn match comment "\v(^\s*//.*\n)+" fold

This is a multiline match that folds consecutive lines beginning with whitespace and double slashes. The "\v" in the beginning labels the pattern "very magic" for brevity. Seems to work.