class Bundler::Graph

def populate
  return if @populated
  # hash of name => GraphNode
  @nodes = {}
  @groups = {}
  # Populate @nodes
  @env.specs.each { |spec| @nodes[spec.name] = GraphNode.new(spec.name, spec.version) }
  # For gems in Gemfile, add details
  @env.current_dependencies.each do |dependency|
    next unless node = @nodes[dependency.name]
    node.is_user = true
    dependency.groups.each do |group|
      if @groups.has_key? group
        group = @groups[group]
      else
        group = @groups[group] = []
      end
      group << dependency
    end
  end
  # walk though a final time and add edges
  @env.specs.each do |spec|
    from = @nodes[spec.name]
    spec.runtime_dependencies.each do |dependency|
      from.dependencies << dependency
    end
  end
  @nodes.freeze
  @groups.freeze
  @populated = true
end