traverse

# File lib/rubygems/specification.rb, line 2647
  def traverse trail = [], visited = {}, &block
    trail.push(self)
    begin
      dependencies.each do |dep|
        next unless dep.runtime?
        dep.to_specs.each do |dep_spec|
          next if visited.has_key?(dep_spec)
          visited[dep_spec] = true
          trail.push(dep_spec)
          begin
            result = block[self, dep, dep_spec, trail]
          ensure
            trail.pop
          end
          unless result == :next
            spec_name = dep_spec.name
            dep_spec.traverse(trail, visited, &block) unless
              trail.any? { |s| s.name == spec_name }
          end
        end
      end
    ensure
      trail.pop
    end
  end