old_contents: import re, csv
  
  from scrapy.http import Response
  from scrapy.selector import XmlXPathSelector
  from scrapy import log
  from scrapy.utils.python import re_rsearch, str_to_unicode
  from scrapy.utils.response import body_or_str
  
  
  def xmliter(obj, nodename):
      """Return a iterator of XPathSelector's over all nodes of a XML document,
         given tha name of the node to iterate. Useful for parsing XML feeds.
  
      obj can be:
      - a Response object
      - a unicode string
      - a string encoded as utf-8
      """
      HEADER_START_RE = re.compile(r'^(.*?)<\s*%s(?:\s|>)' % nodename, re.S)
      HEADER_END_RE = re.compile(r'<\s*/%s\s*>' % nodename, re.S)
      text = body_or_str(obj)
  
      header_start = re.search(HEADER_START_RE, text)
      header_start = header_start.group(1).strip() if header_start else ''
      header_end = re_rsearch(HEADER_END_RE, text)
      header_end = text[header_end[1]:].strip() if header_end else ''
  
      r = re.compile(r"<%s[\s>].*?</%s>" % (nodename, nodename), re.DOTALL)
      for match in r.finditer(text):
          nodetext = header_start + match.group() + header_end
          yield XmlXPathSelector(text=nodetext).select('//' + nodename)[0]
  
  
  def csviter(obj, delimiter=None, headers=None, encoding=None):
      """ Returns an iterator of dictionaries from the given csv object
  
      obj can be:
      - a Response object
      - a unicode string
      - a string encoded as utf-8
  
      delimiter is the character used to separate field on the given obj.
  
      headers is an iterable that when provided offers the keys
      for the returned dictionaries, if not the first row is used.
      """
      encoding = obj.encoding if isinstance(obj, Response) else encoding or 'utf-8'
      def _getrow(csv_r):
          return [str_to_unicode(field, encoding) for field in csv_r.next()]
  
      lines = body_or_str(obj, unicode=False).splitlines(True)
      if delimiter:
          csv_r = csv.reader(lines, delimiter=delimiter)
      else:
          csv_r = csv.reader(lines)
  
      if not headers:
          headers = _getrow(csv_r)
  
      while True:
          row = _getrow(csv_r)
          if len(row) != len(headers):
              log.msg("ignoring row %d (length: %d, should be: %d)" % (csv_r.line_num, len(row), len(headers)), log.WARNING)
              continue
          else:
              yield dict(zip(headers, row))
  
  
new_contents: import re, csv
  from cStringIO import StringIO
  
  from scrapy.http import Response
  from scrapy.selector import XmlXPathSelector
  from scrapy import log
  from scrapy.utils.python import re_rsearch, str_to_unicode
  from scrapy.utils.response import body_or_str
  
  
  def xmliter(obj, nodename):
      """Return a iterator of XPathSelector's over all nodes of a XML document,
         given tha name of the node to iterate. Useful for parsing XML feeds.
  
      obj can be:
      - a Response object
      - a unicode string
      - a string encoded as utf-8
      """
      HEADER_START_RE = re.compile(r'^(.*?)<\s*%s(?:\s|>)' % nodename, re.S)
      HEADER_END_RE = re.compile(r'<\s*/%s\s*>' % nodename, re.S)
      text = body_or_str(obj)
  
      header_start = re.search(HEADER_START_RE, text)
      header_start = header_start.group(1).strip() if header_start else ''
      header_end = re_rsearch(HEADER_END_RE, text)
      header_end = text[header_end[1]:].strip() if header_end else ''
  
      r = re.compile(r"<%s[\s>].*?</%s>" % (nodename, nodename), re.DOTALL)
      for match in r.finditer(text):
          nodetext = header_start + match.group() + header_end
          yield XmlXPathSelector(text=nodetext).select('//' + nodename)[0]
  
  
  def csviter(obj, delimiter=None, headers=None, encoding=None):
      """ Returns an iterator of dictionaries from the given csv object
  
      obj can be:
      - a Response object
      - a unicode string
      - a string encoded as utf-8
  
      delimiter is the character used to separate field on the given obj.
  
      headers is an iterable that when provided offers the keys
      for the returned dictionaries, if not the first row is used.
      """
      encoding = obj.encoding if isinstance(obj, Response) else encoding or 'utf-8'
      def _getrow(csv_r):
          return [str_to_unicode(field, encoding) for field in csv_r.next()]
  
      lines = StringIO(body_or_str(obj, unicode=False))
      if delimiter:
          csv_r = csv.reader(lines, delimiter=delimiter)
      else:
          csv_r = csv.reader(lines)
  
      if not headers:
          headers = _getrow(csv_r)
  
      while True:
          row = _getrow(csv_r)
          if len(row) != len(headers):
              log.msg("ignoring row %d (length: %d, should be: %d)" % (csv_r.line_num, len(row), len(headers)), log.WARNING)
              continue
          else:
              yield dict(zip(headers, row))
  
  
subject: improve csviter memeory usage by use of a generator instead of splitlines