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72 lines
2.3 KiB
Python
72 lines
2.3 KiB
Python
""" html parser to clean up incoming text from unknown sources """
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from html.parser import HTMLParser
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class InputHtmlParser(HTMLParser): # pylint: disable=abstract-method
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"""Removes any html that isn't allowed_tagsed from a block"""
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def __init__(self):
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HTMLParser.__init__(self)
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self.allowed_tags = [
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"p",
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"blockquote",
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"br",
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"b",
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"i",
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"strong",
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"em",
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"pre",
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"a",
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"span",
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"ul",
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"ol",
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"li",
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]
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self.allowed_attrs = ["href", "rel", "src", "alt"]
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self.tag_stack = []
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self.output = []
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# if the html appears invalid, we just won't allow any at all
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self.allow_html = True
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def handle_starttag(self, tag, attrs):
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"""check if the tag is valid"""
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if self.allow_html and tag in self.allowed_tags:
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allowed_attrs = " ".join(
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f'{a}="{v}"' for a, v in attrs if a in self.allowed_attrs
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)
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reconstructed = f"<{tag}"
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if allowed_attrs:
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reconstructed += " " + allowed_attrs
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reconstructed += ">"
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self.output.append(("tag", reconstructed))
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self.tag_stack.append(tag)
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else:
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self.output.append(("data", ""))
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def handle_endtag(self, tag):
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"""keep the close tag"""
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if not self.allow_html or tag not in self.allowed_tags:
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self.output.append(("data", ""))
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return
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if not self.tag_stack or self.tag_stack[-1] != tag:
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# the end tag doesn't match the most recent start tag
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self.allow_html = False
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self.output.append(("data", ""))
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return
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self.tag_stack = self.tag_stack[:-1]
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self.output.append(("tag", f"</{tag}>"))
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def handle_data(self, data):
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"""extract the answer, if we're in an answer tag"""
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self.output.append(("data", data))
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def get_output(self):
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"""convert the output from a list of tuples to a string"""
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if self.tag_stack:
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self.allow_html = False
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if not self.allow_html:
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return "".join(v for (k, v) in self.output if k == "data")
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return "".join(v for (k, v) in self.output)
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