02-parentheticals.rb

sentence = 'Sometimes (when I nest them (my parentheticals) too much (like this (and this))) they get confusing.'

def closing_paren_index( string, opening_paren_index )
  depth = 1
  partial = string.slice opening_paren_index + 1..-1

  partial.each_char.with_index do |char, index|
    if char == '('
      depth += 1
    elsif char == ')'
      then depth -= 1
    end

    if depth == 0
      return index + opening_paren_index + 1
    end
  end

  'No matching parenthesis found.'
end

# puts closing_paren_index( sentence, 3 )
puts closing_paren_index( sentence, 10 )
# puts closing_paren_index( sentence, 28 )
# puts closing_paren_index( sentence, 57 )
# puts closing_paren_index( sentence, 68 )