Question

This seems like it should be fairly simple, but for some reason I can’t think of the right way to do this:

I have a string h that looks something like one(two(three four) five six) seven.

I’d like to split this up into an array of hashes so that the output is something like

{'one' => 
       {'two' => 
              {'three' => nil, 'four' => nil},
        'five'=>nil, 'six'=>nil
       }, 'seven'=>nil}

We can assume that there are equal numbers of parenthesis.

Is there any easy way to do this? In a language that encourages use of for looks, this would be relatively simple; I don’t think I’ve been using Ruby long enough to get a feel for the Ruby way of doing this sort of problem.

Thanks!

Answer 1

Here is a recursive solution:

def f(str)
  parts = ['']
  nesting_level = 0
  str.split('').each do |c|
    if c != ' ' or nesting_level > 0
      parts.last << c
    end
    if [' ', ')'].include?(c) and nesting_level == 0
      parts << ''
    end
    case c
    when '('
      nesting_level += 1
    when ')'
      nesting_level -= 1
    end
  end
  hash = {}
  parts.each do |seg|
    unless seg.include?('(')
      hash[seg] = nil
    else
      key = seg[/^[^\(\) ]+/]
      value = seg[(key.length + 1)..(seg.length - 2)].to_s
      hash[key] = f value
    end
  end
  hash
end

f 'one(two(three four) five six) seven' #=> {"one"=>{"two"=>{"three"=>nil, "four"=>nil}, "five"=>nil, "six"=>nil}, "seven"=>nil}