print a tree in ruby

print_jung_graph_spec.rb

require 'spec_helper'

describe "GraphExperiments" do
  JungGraph = Java::EduUciIcsJungGraph

  before(:each) do
    n = LazyList[1..Infinity]
    @tree = JungGraph::DelegateTree.new
    @tree.setRoot("root")
    @tree.addChild(n.next, "root", "a")
    @tree.addChild(n.next, "root", "b")
    @tree.addChild(n.next, "root", "c")
    @tree.addChild(n.next, "a", "a1")
  end

  it "should have a printer" do
    tp = TreePrinter.new
    tp.is_branch    = proc{|node| @tree.getChildCount(node) > 0 ? true : false }
    tp.get_children = proc{|node| @tree.getChildren(node).to_a }
    puts tp.format(@tree.getRoot)
  end

end

results.txt

root
|-- b
|-- c
`-- a
    `-- a1

tree_printer.rb

module Util
  class TreePrinter
    attr_accessor :is_branch
    attr_accessor :get_children
    attr_accessor :format_node
    attr_accessor :skip_root_node

    def initialize
      @arms = Hash.new("|   ")
      @arms[""]  = ""
      @arms["`"] = "    "
      @out = ""
      @is_branch    = proc{|node| FileTest.directory?(node) && FileTest.readable?(node) }
      @get_children = proc{|node| node.children(false).sort}
      @format_node  = proc{|node| node.to_s}
      @skip_root_node = false
    end
    
    def visit(path, leader, tie, arm, node)
      if(@root == node) && skip_root_node
        # skip
      else
        node_str = @format_node.call(node)
        @out << "#{leader}#{arm}#{tie}#{node_str}\n"
      end
      visitChildren(node, leader + @arms[arm])
      @out
    end
    
    def visitChildren(path, leader)
      kids = []
      if(@root == path) && skip_root_node
        kids = path
      else
        return unless @is_branch.call(path)
        kids = @get_children.call(path)
      end
      return if kids.empty?
      arms = Array.new(kids.length - 1, "|") << "`"
      pairs = kids.zip(arms)
      pairs.each { |e|  visit(path, leader, "-- ", e[1], e[0]) } 
    end

    def format(root)
      @root = root
      visit root, "", "", "", root 
    end
  end
end