[QUIZ] Drawing Trees (#40)

ruby-talk
1

I found my "print binary tree" program, it is dated May 1993 using C language.
I simply modify it to solve this quiz.
The presentation format is not quite what we asked.

···

#----------------------------------------------------------------------------#
public

def to_s( )
  return "[empty heap]" if @heap.size <= 1
  result = ''
  root = 1
      
  if has_right?(root)
    print_node(result, ' ', true, right_index(root))
    result << " |\n"
  end
      
  result << "-o #{@heap[root]}\n"
      
  if has_left?(root)
    result << " |\n"
    print_node(result, ' ', false, left_index(root))
  end
      
  result
end
      
private
      
def left_index( index ) ; index * 2 ; end
def right_index( index ) ; index * 2 + 1 ; end
def has_left?( index ) ; left_index(index) < @heap.size ; end
def has_right?( index ) ; right_index(index) < @heap.size ; end

def print_node( result, line, right, index )
  if has_right?(index)
    print_node(result, line + (right ? ' ' : '| '), true, right_index(index))
    result << "#{line}#{right ? ' ' : '|'} |\n"
  end
      
  result << "#{line}+-o #{@heap[index]}\n"
    
  if has_left?(index)
    result << "#{line}#{right ? '|' : ' '} |\n"
    print_node(result, line + (right ? '| ' : ' '), false, left_index(index))
  end
end
#----------------------------------------------------------------------------#

Some output:
   +-o 22
   >
+-o 15
> >
> +-o 17
> >
> +-o 19
>
-o 12
>
> +-o 51
> >
> +-o 23
> > >
> > +-o 26
> >
+-o 20
   >
   > +-o 40
   > >
   +-o 29
     >
     +-o 35

   +-o heap
   > >
   > +-o this
   >
+-o data
> >
> > +-o the
> > >
> +-o of
> >
> +-o words
>
-o another
>
> +-o on
> >
> +-o kind
> > >
> > +-o random
> >
+-o are
   >
   > +-o test
   > >
   +-o some
     >
     +-o to