gistfile1.rb

# source objects
[
	{:id=>1, :path=>'a::poems::one::1'},
	{:id=>2, :path=>'a::poems::one::2'},
	{:id=>3, :path=>'a::poems::one::3'},
	{:id=>4, :path=>'a::poems::one::4'},
	{:id=>5, :path=>'a::poems::two::1'},
	{:id=>6, :path=>'a::poems::two::2'},
	{:id=>7, :path=>'a::poems::two::3'},
	{:id=>8, :path=>'a::poems::two::4'}
]

# composite output
[
  {:label=>'a', :children=>[
    {:label=>'poems', :children=>[
      {:label=>'one', :children=>[
        {:label=>'1', :id=>1},
        {:label=>'2', :id=>2},
        {:label=>'3', :id=>3},
        {:label=>'4', :id=>4}
      ]},
      {:label=>'two', :children=>[
        {:label=>'1', :id=>5},
        {:label=>'2', :id=>6},
        {:label=>'3', :id=>7},
        {:label=>'4', :id=>8}
      ]}
    ]}
  ]}
]