How to match file pattern, with extension, not containing a specific word?

Question

I'm trying to use autocmd BufNewFile to like so:

autocmd BufNewFile  \(.*_spec\)\@!.rb  0r ~/vim/skeleton.rb  
autocmd BufNewFile  *_spec.rb          0r ~/vim/skeleton_spec.rb

So, I want the first line to match all .rb files NOT ending with _spec.rb, and the second line to only match *_spec.rb files. I've tried various incarnations of the first line to no avail.

Thanks in advance.

Answer 1

You should use a look-behind assertion:

autocmd BufNewFile  *\(_spec\)\@<!.rb  0r ~/vim/skeleton.rb
autocmd BufNewFile  *_spec.rb          0r ~/vim/skeleton_spec.rb

The glob pattern *\(_spec\)\@<!.rb is converted to regular expression \(_spec\)\@<!\.rb$ which breaks down as follows:

             \.rb       match literal ".rb"
                 $      this must be the end of the filename
\(_spec\)\@<!           provided "_spec" does not appear right before the dot