moviewyrm/fedireads/sanitize_html.py

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''' html parser to clean up incoming text from unknown sources '''
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from html.parser import HTMLParser
class InputHtmlParser(HTMLParser):
''' Removes any html that isn't whitelisted from a block '''
def __init__(self):
HTMLParser.__init__(self)
self.whitelist = ['p', 'b', 'i', 'pre', 'a', 'span']
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self.tag_stack = []
self.output = []
# if the html appears invalid, we just won't allow any at all
self.allow_html = True
def handle_starttag(self, tag, attrs):
''' check if the tag is valid '''
if self.allow_html and tag in self.whitelist:
self.output.append(('tag', self.get_starttag_text()))
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self.tag_stack.append(tag)
else:
self.output.append(('data', ''))
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def handle_endtag(self, tag):
''' keep the close tag '''
if not self.allow_html or tag not in self.whitelist:
self.output.append(('data', ''))
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return
if not self.tag_stack or self.tag_stack[-1] != tag:
# the end tag doesn't match the most recent start tag
self.allow_html = False
self.output.append(('data', ''))
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return
self.tag_stack = self.tag_stack[:-1]
self.output.append(('tag', '</%s>' % tag))
def handle_data(self, data):
''' extract the answer, if we're in an answer tag '''
self.output.append(('data', data))
def get_output(self):
''' convert the output from a list of tuples to a string '''
if self.tag_stack:
self.allow_html = False
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if not self.allow_html:
return ''.join(v for (k, v) in self.output if k == 'data')
return ''.join(v for (k, v) in self.output)