class Sass::Plugin::Listener

@private
files, as well as a somewhat cleaner event dispatch API.
A wrapper around the Listen gem. Adds support for listening to individual

def directory(path, events) 

def directory(path, events)
  (@directories[path] ||= []) << events
end

def file(path, events) 

def file(path, events)
  file_base = File.basename(path)
  directory(File.dirname(path), {
      :modified => file_event_fn(events[:modified], file_base),
      :added => file_event_fn(events[:added], file_base),
      :removed => file_event_fn(events[:removed], file_base)
    })
end

def file_event_fn(event, file_base) 

def file_event_fn(event, file_base)
  lambda do |dir, base|
    next unless event
    next unless base == file_base
    event.call
  end
end

def initialize 

def initialize
  @directories = {}
  yield self
  begin
    start!
  rescue Exception => e
    raise e unless e.is_a?(Interrupt)
  end
end

def run_events(paths, event, path) 

def run_events(paths, event, path)
  return if paths.nil? || event.nil?
  paths.each {|p| event[File.dirname(p), File.basename(p)]}
end

def start! 

def start!
  listener = Listen::MultiListener.new(*@directories.keys) do |modified, added, removed|
    modified = modified.group_by {|path| File.dirname(path)}
    added = added.group_by {|path| File.dirname(path)}
    removed = removed.group_by {|path| File.dirname(path)}
    @directories.each do |dir, events|
      events.each do |e|
        run_events(modified[dir], e[:modified], dir)
        run_events(added[dir], e[:added], dir)
        run_events(removed[dir], e[:removed], dir)
      end
    end
  end.start
end