import htmlentitydefs
import re

def delete_byte_codes(string):
    '''
    Remove byte codes (\\x00, \\x01, ..., \\x1f) from string and return result string.
    Need remove this codes for correct parsing XML (for example)
    '''

    byte_codes = [u'\x00', u'\x01', u'\x02', u'\x03', u'\x04', u'\x05', u'\x06', u'\x07', u'\x08', u'\x09',
                  u'\x0a', u'\x0b', u'\x0c', u'\x0d', u'\x0e', u'\x0f',
                  u'\x10', u'\x11', u'\x12', u'\x13', u'\x14', u'\x15', u'\x16', u'\x17', u'\x18', u'\x19',
                  u'\x1a', u'\x1b', u'\x1c', u'\x1d', u'\x1e', u'\x1f']
    res_str = string
    for char in byte_codes:
        res_str = res_str.replace(char, u'')

    return res_str
    

def unescape(text):
   """Removes HTML or XML character references 
      and entities from a text string.
   @param text The HTML (or XML) source text.
   @return The plain text, as a Unicode string, if necessary.
   from Fredrik Lundh
   2008-01-03: input only unicode characters string.
   http://effbot.org/zone/re-sub.htm#unescape-html
   """
   def fixup(m):
      text = m.group(0)
      if text[:2] == "&#":
         # character reference
         try:
            if text[:3] == "&#x":
               return unichr(int(text[3:-1], 16))
            else:
               return unichr(int(text[2:-1]))
         except ValueError:
            print "Value Error"
            pass
      else:
         # named entity
         # reescape the reserved characters.
         try:
            if text[1:-1] == "amp":
               text = "&"
            elif text[1:-1] == "gt":
               text = ">"
            elif text[1:-1] == "lt":
               text = "<"
            else:
               print text[1:-1]
               text = unichr(htmlentitydefs.name2codepoint[text[1:-1]])
         except KeyError:
            print "keyerror"
            pass
      return text # leave as is
   return re.sub("&#?\w+;", fixup, text)