# File lib/hpricot/traverse.rb, line 199
    def search(expr, &blk)
      last = nil
      nodes = [self]
      done = []
      expr = expr.to_s
      hist = []
      until expr.empty?
          expr = clean_path(expr)
          expr.gsub!(%r!^//!, '')

          case expr
          when %r!^/?\.\.!
              last = expr = $'
              nodes.map! { |node| node.parent }
          when %r!^[>/]!
              last = expr = $'
              nodes = Elements[*nodes.map { |node| node.children if node.respond_to? :children }.flatten.compact]
          when %r!^\+!
              last = expr = $'
              nodes.map! do |node|
                  siblings = node.parent.children
                  siblings[siblings.index(node)+1]
              end
              nodes.compact!
          when %r!^~!
              last = expr = $'
              nodes.map! do |node|
                  siblings = node.parent.children
                  siblings[(siblings.index(node)+1)..-1]
              end
              nodes.flatten!
          when %r!^[|,]!
              last = expr = " #$'"
              nodes.shift if nodes.first == self
              done += nodes
              nodes = [self]
          else
              m = expr.match(%r!^([#.]?)([a-z0-9\\*_-]*)!i).to_a
              if m[1] == '#'
                  oid = get_element_by_id(m[2])
                  nodes = oid ? [oid] : []
                  expr = $'
              else
                  m[2] = "*" if $' =~ /^\(\)/ || m[2] == "" || m[1] == "."
                  ret = []
                  nodes.each do |node|
                      case m[2]
                      when '*'
                          node.traverse_element { |n| ret << n }
                      else
                          if node.respond_to? :get_elements_by_tag_name
                            ret += [*node.get_elements_by_tag_name(m[2])] - [*(node unless last)]
                          end
                      end
                  end
                  nodes = ret
              end
              last = nil
          end

          hist << expr
          break if hist[-1] == hist[-2]
          nodes, expr = Elements.filter(nodes, expr)
      end
      nodes = done + nodes.flatten.uniq
      if blk
          nodes.each(&blk)
          self
      else
          Elements[*nodes]
      end
    end