parsing XML chunk by chunk

gistfile1.rb

# <xml version="1.0" encoding="UTF-8">
# <DataFeeds>
#   <Item>
#     ....
#   </Item>
#   <Item>
#     ...
#   </Item>
# </DataFeeds>

    File.open("really_big_file.xml") do |file|
      item_i = 0
      while line = file.gets
        next if line =~ /xml version="1.0" encoding="UTF-8"/
        next if line =~ /<DataFeeds>/
      
        # START TAG
        if line =~ /<Item>/
          item_i += 1
          chunk = ""
        end
        
        chunk << line
      
        # END TAG
        if line =~ /<\/Item>/
            doc = Nokogiri::HTML(chunk)
            # ....
        end
      end # while end            
    end # file end