class ActionDispatch::Journey::Path::Pattern

def offsets
  return @offsets if @offsets
  @offsets = [0]
  spec.find_all(&:symbol?).each do |node|
    node = node.to_sym
    if @requirements.key?(node)
      re = /#{@requirements[node]}|/
      @offsets.push((re.match('').length - 1) + @offsets.last)
    else
      @offsets << @offsets.last
    end
  end
  @offsets
end