class SassListen::Adapter::Darwin

def self.usable?
  require 'rb-fsevent'
  darwin_version = RbConfig::CONFIG['target_os'][OS_REGEXP, :major_version] or return false
  return true if darwin_version.to_i >= 13 # darwin13 is OS X 10.9
  return true if Gem::Version.new(FSEvent::VERSION) <= Gem::Version.new('0.9.4')
  Kernel.warn INCOMPATIBLE_GEM_VERSION
  false
end