From: Adam Shelly <adam.shelly@...>
Date: 2008-02-12T09:24:12+09:00
Subject: Re: nested hash from array of paths

On 2/11/08, Adam Groves <adam.groves@gmail.com> wrote:
> array = ["home", "about", "about/history", "about/company",
> "about/history/part1", "about/history/part2"]
>
> I want to build a tree from this array in the form of a nested hash:
>
>
> {"home" => nil, "about => {"history => ["part1" => nil, "part2" =>
> nil]", "company" => nil}}
>
> Any ideas as to how best to solve this?
>

I could only figure out how to do it using 2 passes:

tree ={}
array.sort.each{|w|
  h=tree
  w.split('/').each{|part| h=h[part]||=Hash.new}
}

def cleanup h
  return true if h.empty?
  h.find_all{|k,v|h[k]=nil if v.is_a?(Hash)&&cleanup(v)}
  false
end

cleanup tree
p tree
=> {"about"=>{"company"=>nil, "history"=>{"part1"=>nil,
"part2"=>nil}}, "home"=>nil}


-Adam