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#1486713: Add a tolerant mode to HTMLParser.
The motivation for adding this option is that the the functionality it provides used to be provided by sgmllib in Python2, and was used by, for example, BeautifulSoup. Without this option, the Python3 version of BeautifulSoup and the many programs that use it are crippled. The original patch was by 'kxroberto'. I modified it heavily but kept his heuristics and test. I also added additional heuristics to fix #975556, #1046092, and part of #6191. This patch should be completely backward compatible: the behavior with the default strict=True is unchanged.
This commit is contained in:
R. David Murray
parent
79cdb661f5
commit
b579dba119
4 changed files with 139 additions and 24 deletions
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@ -24,10 +24,14 @@ starttagopen = re.compile('<[a-zA-Z]')
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piclose = re.compile('>')
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commentclose = re.compile(r'--\s*>')
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tagfind = re.compile('[a-zA-Z][-.a-zA-Z0-9:_]*')
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# Note, the strict one of this pair isn't really strict, but we can't
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# make it correctly strict without breaking backward compatibility.
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attrfind = re.compile(
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r'\s*([a-zA-Z_][-.:a-zA-Z_0-9]*)(\s*=\s*'
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r'(\'[^\']*\'|"[^"]*"|[-a-zA-Z0-9./,:;+*%?!&$\(\)_#=~@]*))?')
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attrfind_tolerant = re.compile(
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r'\s*([a-zA-Z_][-.:a-zA-Z_0-9]*)(\s*=\s*'
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r'(\'[^\']*\'|"[^"]*"|[^>\s]*))?')
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locatestarttagend = re.compile(r"""
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<[a-zA-Z][-.a-zA-Z0-9:_]* # tag name
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(?:\s+ # whitespace before attribute name
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@ -42,6 +46,21 @@ locatestarttagend = re.compile(r"""
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)*
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\s* # trailing whitespace
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""", re.VERBOSE)
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locatestarttagend_tolerant = re.compile(r"""
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<[a-zA-Z][-.a-zA-Z0-9:_]* # tag name
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(?:\s* # optional whitespace before attribute name
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(?:[a-zA-Z_][-.:a-zA-Z0-9_]* # attribute name
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(?:\s*=\s* # value indicator
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(?:'[^']*' # LITA-enclosed value
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|\"[^\"]*\" # LIT-enclosed value
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|[^'\">\s]+ # bare value
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)
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(?:\s*,)* # possibly followed by a comma
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)?
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)
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)*
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\s* # trailing whitespace
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""", re.VERBOSE)
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endendtag = re.compile('>')
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endtagfind = re.compile('</\s*([a-zA-Z][-.a-zA-Z0-9:_]*)\s*>')
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@ -86,9 +105,15 @@ class HTMLParser(_markupbase.ParserBase):
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CDATA_CONTENT_ELEMENTS = ("script", "style")
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def __init__(self, strict=True):
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"""Initialize and reset this instance.
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def __init__(self):
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"""Initialize and reset this instance."""
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If strict is set to True (the default), errors are raised when invalid
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HTML is encountered. If set to False, an attempt is instead made to
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continue parsing, making "best guesses" about the intended meaning, in
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a fashion similar to what browsers typically do.
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"""
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self.strict = strict
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self.reset()
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def reset(self):
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@ -160,9 +185,18 @@ class HTMLParser(_markupbase.ParserBase):
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else:
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break
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if k < 0:
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if end:
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if not end:
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break
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if self.strict:
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self.error("EOF in middle of construct")
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break
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k = rawdata.find('>', i + 1)
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if k < 0:
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k = rawdata.find('<', i + 1)
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if k < 0:
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k = i + 1
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else:
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k += 1
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self.handle_data(rawdata[i:k])
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i = self.updatepos(i, k)
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elif startswith("&#", i):
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match = charref.match(rawdata, i)
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@ -193,7 +227,12 @@ class HTMLParser(_markupbase.ParserBase):
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if match:
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# match.group() will contain at least 2 chars
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if end and match.group() == rawdata[i:]:
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self.error("EOF in middle of entity or char ref")
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if self.strict:
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self.error("EOF in middle of entity or char ref")
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else:
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if k <= i:
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k = n
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i = self.updatepos(i, i + 1)
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# incomplete
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break
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elif (i + 1) < n:
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@ -240,7 +279,10 @@ class HTMLParser(_markupbase.ParserBase):
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self.lasttag = tag = rawdata[i+1:k].lower()
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while k < endpos:
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m = attrfind.match(rawdata, k)
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if self.strict:
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m = attrfind.match(rawdata, k)
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else:
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m = attrfind_tolerant.search(rawdata, k)
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if not m:
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break
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attrname, rest, attrvalue = m.group(1, 2, 3)
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@ -262,8 +304,11 @@ class HTMLParser(_markupbase.ParserBase):
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- self.__starttag_text.rfind("\n")
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else:
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offset = offset + len(self.__starttag_text)
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self.error("junk characters in start tag: %r"
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% (rawdata[k:endpos][:20],))
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if self.strict:
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self.error("junk characters in start tag: %r"
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% (rawdata[k:endpos][:20],))
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self.handle_data(rawdata[i:endpos])
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return endpos
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if end.endswith('/>'):
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# XHTML-style empty tag: <span attr="value" />
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self.handle_startendtag(tag, attrs)
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@ -277,7 +322,10 @@ class HTMLParser(_markupbase.ParserBase):
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# or -1 if incomplete.
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def check_for_whole_start_tag(self, i):
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rawdata = self.rawdata
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m = locatestarttagend.match(rawdata, i)
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if self.strict:
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m = locatestarttagend.match(rawdata, i)
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else:
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m = locatestarttagend_tolerant.match(rawdata, i)
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if m:
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j = m.end()
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next = rawdata[j:j+1]
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@ -290,8 +338,13 @@ class HTMLParser(_markupbase.ParserBase):
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# buffer boundary
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return -1
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# else bogus input
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self.updatepos(i, j + 1)
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self.error("malformed empty start tag")
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if self.strict:
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self.updatepos(i, j + 1)
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self.error("malformed empty start tag")
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if j > i:
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return j
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else:
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return i + 1
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if next == "":
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# end of input
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return -1
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@ -300,8 +353,13 @@ class HTMLParser(_markupbase.ParserBase):
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# end of input in or before attribute value, or we have the
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# '/' from a '/>' ending
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return -1
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self.updatepos(i, j)
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self.error("malformed start tag")
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if self.strict:
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self.updatepos(i, j)
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self.error("malformed start tag")
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if j > i:
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return j
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else:
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return i + 1
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raise AssertionError("we should not get here!")
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# Internal -- parse endtag, return end or -1 if incomplete
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@ -314,7 +372,15 @@ class HTMLParser(_markupbase.ParserBase):
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j = match.end()
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match = endtagfind.match(rawdata, i) # </ + tag + >
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if not match:
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self.error("bad end tag: %r" % (rawdata[i:j],))
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if self.strict:
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self.error("bad end tag: %r" % (rawdata[i:j],))
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k = rawdata.find('<', i + 1, j)
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if k > i:
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j = k
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if j <= i:
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j = i + 1
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self.handle_data(rawdata[i:j])
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return j
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tag = match.group(1)
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self.handle_endtag(tag.lower())
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self.clear_cdata_mode()
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@ -358,7 +424,8 @@ class HTMLParser(_markupbase.ParserBase):
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pass
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def unknown_decl(self, data):
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self.error("unknown declaration: %r" % (data,))
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if self.strict:
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self.error("unknown declaration: %r" % (data,))
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# Internal -- helper to remove special character quoting
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entitydefs = None
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