palindrome.rb

class String
  def palindrome?
    head = 0
    tail = length - 1

    while head <= tail
      # Normalize head
      head += 1 while self[head] && (self[head] =~ /\W/)

      # Normalize tail
      tail -= 1 while self[tail] && (self[tail] =~ /\W/)

      return false unless self[head].downcase == self[tail].downcase

      head += 1
      tail -= 1
    end

    true
  end
end