class StackProf::Report

def +(other)
  raise ArgumentError, "cannot combine #{other.class}" unless self.class == other.class
  raise ArgumentError, "cannot combine #{modeline} with #{other.modeline}" unless modeline == other.modeline
  raise ArgumentError, "cannot combine v#{version} with v#{other.version}" unless version == other.version
  f1, f2 = normalized_frames, other.normalized_frames
  frames = (f1.keys + f2.keys).uniq.inject(Hash.new) do |hash, id|
    if f1[id].nil?
      hash[id] = f2[id]
    elsif f2[id]
      hash[id] = f1[id]
      hash[id][:total_samples] += f2[id][:total_samples]
      hash[id][:samples] += f2[id][:samples]
      if f2[id][:edges]
        edges = hash[id][:edges] ||= {}
        f2[id][:edges].each do |edge, weight|
          edges[edge] ||= 0
          edges[edge] += weight
        end
      end
      if f2[id][:lines]
        lines = hash[id][:lines] ||= {}
        f2[id][:lines].each do |line, weight|
          lines[line] = add_lines(lines[line], weight)
        end
      end
    else
      hash[id] = f1[id]
    end
    hash
  end
  d1, d2 = data, other.data
  data = {
    version: version,
    mode: d1[:mode],
    interval: d1[:interval],
    samples: d1[:samples] + d2[:samples],
    gc_samples: d1[:gc_samples] + d2[:gc_samples],
    missed_samples: d1[:missed_samples] + d2[:missed_samples],
    frames: frames
  }
  self.class.new(data)
end