python strip_tags实现

Sometimes it is necessary to remove all (or some subset of) xml style tags (eg. <p></p>) from a string. If you're familiar with PHP, then you probably already know about the <a href="http://php.net/manual/en/function.strip-tags.php">strip_tags()</a> function. Here is a simple equivalent to strip_tags() written in Python.

## Remove xml style tags from an input string.
#
#  @param string The input string.
#  @param allowed_tags A string to specify tags which should not be removed.
def strip_tags(string, allowed_tags=''):
  if allowed_tags != '':
    # Get a list of all allowed tag names.
    allowed_tags_list = re.sub(r'[\/<> ]+', '', allowed_tags).split(',')
    allowed_pattern = ''
    for s in allowed_tags_list:
      if s == '':
       continue;
      # Add all possible patterns for this tag to the regex.
      if allowed_pattern != '':
        allowed_pattern += '|'
      allowed_pattern += '<' + s + ' [^><]*>$|<' + s + '>|'
    # Get all tags included in the string.
    all_tags = re.findall(r'<]+>', string, re.I)
    for tag in all_tags:
      # If not allowed, replace it.
      if not re.match(allowed_pattern, tag, re.I):
        string = string.replace(tag, '')
  else:
    # If no allowed tags, remove all.
    string = re.sub(r'<[^>]*?>', '', string)
  return string

Sample output

>>> strip_tags('Hello World! 
')
'Hello World! '
>>> strip_tags('Hello World! 
', '')
'Hello World!'
>>> strip_tags('Hello World! 
', ',
')
'Hello World! 
'
>>>