class Bundler::PubGrub::Term

def relation(other)
  if positive? && other.positive?
    constraint.relation(other.constraint)
  elsif negative? && other.positive?
    if constraint.allows_all?(other.constraint)
      :disjoint
    else
      :overlap
    end
  elsif positive? && other.negative?
    if !other.constraint.allows_any?(constraint)
      :subset
    elsif other.constraint.allows_all?(constraint)
      :disjoint
    else
      :overlap
    end
  elsif negative? && other.negative?
    if constraint.allows_all?(other.constraint)
      :subset
    else
      :overlap
    end
  else
    raise
  end
end