463 lines
17 KiB
Python
463 lines
17 KiB
Python
"""A parser for HTML and XHTML."""
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# This file is based on sgmllib.py, but the API is slightly different.
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# XXX There should be a way to distinguish between PCDATA (parsed
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# character data -- the normal case), RCDATA (replaceable character
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# data -- only char and entity references and end tags are special)
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# and CDATA (character data -- only end tags are special).
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import re
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import _markupbase
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from html import unescape
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__all__ = ['HTMLParser']
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# Regular expressions used for parsing
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interesting_normal = re.compile('[&<]')
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incomplete = re.compile('&[a-zA-Z#]')
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entityref = re.compile('&([a-zA-Z][-.a-zA-Z0-9]*)[^a-zA-Z0-9]')
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charref = re.compile('&#(?:[0-9]+|[xX][0-9a-fA-F]+)[^0-9a-fA-F]')
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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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# Note:
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# 1) if you change tagfind/attrfind remember to update locatestarttagend too;
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# 2) if you change tagfind/attrfind and/or locatestarttagend the parser will
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# explode, so don't do it.
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# see http://www.w3.org/TR/html5/tokenization.html#tag-open-state
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# and http://www.w3.org/TR/html5/tokenization.html#tag-name-state
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tagfind_tolerant = re.compile(r'([a-zA-Z][^\t\n\r\f />\x00]*)(?:\s|/(?!>))*')
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attrfind_tolerant = re.compile(
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r'((?<=[\'"\s/])[^\s/>][^\s/=>]*)(\s*=+\s*'
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r'(\'[^\']*\'|"[^"]*"|(?![\'"])[^>\s]*))?(?:\s|/(?!>))*')
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locatestarttagend_tolerant = re.compile(r"""
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<[a-zA-Z][^\t\n\r\f />\x00]* # tag name
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(?:[\s/]* # optional whitespace before attribute name
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(?:(?<=['"\s/])[^\s/>][^\s/=>]* # 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 space
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)?(?:\s|/(?!>))*
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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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# the HTML 5 spec, section 8.1.2.2, doesn't allow spaces between
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# </ and the tag name, so maybe this should be fixed
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endtagfind = re.compile(r'</\s*([a-zA-Z][-.a-zA-Z0-9:_]*)\s*>')
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class HTMLParser(_markupbase.ParserBase):
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"""Find tags and other markup and call handler functions.
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Usage:
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p = HTMLParser()
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p.feed(data)
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...
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p.close()
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Start tags are handled by calling self.handle_starttag() or
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self.handle_startendtag(); end tags by self.handle_endtag(). The
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data between tags is passed from the parser to the derived class
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by calling self.handle_data() with the data as argument (the data
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may be split up in arbitrary chunks). If convert_charrefs is
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True the character references are converted automatically to the
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corresponding Unicode character (and self.handle_data() is no
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longer split in chunks), otherwise they are passed by calling
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self.handle_entityref() or self.handle_charref() with the string
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containing respectively the named or numeric reference as the
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argument.
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"""
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CDATA_CONTENT_ELEMENTS = ("script", "style")
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def __init__(self, *, convert_charrefs=True):
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"""Initialize and reset this instance.
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If convert_charrefs is True (the default), all character references
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are automatically converted to the corresponding Unicode characters.
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"""
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self.convert_charrefs = convert_charrefs
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self.reset()
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def reset(self):
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"""Reset this instance. Loses all unprocessed data."""
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self.rawdata = ''
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self.lasttag = '???'
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self.interesting = interesting_normal
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self.cdata_elem = None
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_markupbase.ParserBase.reset(self)
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def feed(self, data):
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r"""Feed data to the parser.
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Call this as often as you want, with as little or as much text
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as you want (may include '\n').
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"""
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self.rawdata = self.rawdata + data
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self.goahead(0)
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def close(self):
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"""Handle any buffered data."""
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self.goahead(1)
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__starttag_text = None
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def get_starttag_text(self):
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"""Return full source of start tag: '<...>'."""
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return self.__starttag_text
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def set_cdata_mode(self, elem):
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self.cdata_elem = elem.lower()
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self.interesting = re.compile(r'</\s*%s\s*>' % self.cdata_elem, re.I)
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def clear_cdata_mode(self):
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self.interesting = interesting_normal
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self.cdata_elem = None
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# Internal -- handle data as far as reasonable. May leave state
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# and data to be processed by a subsequent call. If 'end' is
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# true, force handling all data as if followed by EOF marker.
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def goahead(self, end):
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rawdata = self.rawdata
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i = 0
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n = len(rawdata)
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while i < n:
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if self.convert_charrefs and not self.cdata_elem:
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j = rawdata.find('<', i)
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if j < 0:
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# if we can't find the next <, either we are at the end
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# or there's more text incoming. If the latter is True,
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# we can't pass the text to handle_data in case we have
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# a charref cut in half at end. Try to determine if
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# this is the case before proceeding by looking for an
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# & near the end and see if it's followed by a space or ;.
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amppos = rawdata.rfind('&', max(i, n-34))
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if (amppos >= 0 and
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not re.compile(r'[\s;]').search(rawdata, amppos)):
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break # wait till we get all the text
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j = n
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else:
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match = self.interesting.search(rawdata, i) # < or &
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if match:
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j = match.start()
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else:
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if self.cdata_elem:
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break
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j = n
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if i < j:
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if self.convert_charrefs and not self.cdata_elem:
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self.handle_data(unescape(rawdata[i:j]))
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else:
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self.handle_data(rawdata[i:j])
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i = self.updatepos(i, j)
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if i == n: break
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startswith = rawdata.startswith
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if startswith('<', i):
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if starttagopen.match(rawdata, i): # < + letter
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k = self.parse_starttag(i)
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elif startswith("</", i):
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k = self.parse_endtag(i)
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elif startswith("<!--", i):
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k = self.parse_comment(i)
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elif startswith("<?", i):
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k = self.parse_pi(i)
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elif startswith("<!", i):
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k = self.parse_html_declaration(i)
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elif (i + 1) < n:
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self.handle_data("<")
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k = i + 1
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else:
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break
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if k < 0:
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if not end:
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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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if self.convert_charrefs and not self.cdata_elem:
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self.handle_data(unescape(rawdata[i:k]))
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else:
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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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if match:
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name = match.group()[2:-1]
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self.handle_charref(name)
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k = match.end()
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if not startswith(';', k-1):
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k = k - 1
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i = self.updatepos(i, k)
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continue
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else:
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if ";" in rawdata[i:]: # bail by consuming &#
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self.handle_data(rawdata[i:i+2])
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i = self.updatepos(i, i+2)
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break
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elif startswith('&', i):
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match = entityref.match(rawdata, i)
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if match:
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name = match.group(1)
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self.handle_entityref(name)
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k = match.end()
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if not startswith(';', k-1):
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k = k - 1
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i = self.updatepos(i, k)
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continue
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match = incomplete.match(rawdata, i)
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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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k = match.end()
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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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# not the end of the buffer, and can't be confused
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# with some other construct
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self.handle_data("&")
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i = self.updatepos(i, i + 1)
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else:
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break
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else:
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assert 0, "interesting.search() lied"
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# end while
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if end and i < n and not self.cdata_elem:
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if self.convert_charrefs and not self.cdata_elem:
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self.handle_data(unescape(rawdata[i:n]))
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else:
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self.handle_data(rawdata[i:n])
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i = self.updatepos(i, n)
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self.rawdata = rawdata[i:]
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# Internal -- parse html declarations, return length or -1 if not terminated
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# See w3.org/TR/html5/tokenization.html#markup-declaration-open-state
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# See also parse_declaration in _markupbase
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def parse_html_declaration(self, i):
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rawdata = self.rawdata
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assert rawdata[i:i+2] == '<!', ('unexpected call to '
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'parse_html_declaration()')
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if rawdata[i:i+4] == '<!--':
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# this case is actually already handled in goahead()
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return self.parse_comment(i)
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elif rawdata[i:i+3] == '<![':
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return self.parse_marked_section(i)
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elif rawdata[i:i+9].lower() == '<!doctype':
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# find the closing >
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gtpos = rawdata.find('>', i+9)
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if gtpos == -1:
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return -1
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self.handle_decl(rawdata[i+2:gtpos])
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return gtpos+1
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else:
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return self.parse_bogus_comment(i)
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# Internal -- parse bogus comment, return length or -1 if not terminated
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# see http://www.w3.org/TR/html5/tokenization.html#bogus-comment-state
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def parse_bogus_comment(self, i, report=1):
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rawdata = self.rawdata
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assert rawdata[i:i+2] in ('<!', '</'), ('unexpected call to '
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'parse_comment()')
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pos = rawdata.find('>', i+2)
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if pos == -1:
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return -1
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if report:
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self.handle_comment(rawdata[i+2:pos])
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return pos + 1
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# Internal -- parse processing instr, return end or -1 if not terminated
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def parse_pi(self, i):
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rawdata = self.rawdata
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assert rawdata[i:i+2] == '<?', 'unexpected call to parse_pi()'
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match = piclose.search(rawdata, i+2) # >
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if not match:
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return -1
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j = match.start()
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self.handle_pi(rawdata[i+2: j])
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j = match.end()
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return j
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# Internal -- handle starttag, return end or -1 if not terminated
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def parse_starttag(self, i):
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self.__starttag_text = None
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endpos = self.check_for_whole_start_tag(i)
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if endpos < 0:
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return endpos
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rawdata = self.rawdata
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self.__starttag_text = rawdata[i:endpos]
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# Now parse the data between i+1 and j into a tag and attrs
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attrs = []
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match = tagfind_tolerant.match(rawdata, i+1)
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assert match, 'unexpected call to parse_starttag()'
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k = match.end()
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self.lasttag = tag = match.group(1).lower()
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while k < endpos:
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m = attrfind_tolerant.match(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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if not rest:
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attrvalue = None
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elif attrvalue[:1] == '\'' == attrvalue[-1:] or \
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attrvalue[:1] == '"' == attrvalue[-1:]:
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attrvalue = attrvalue[1:-1]
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if attrvalue:
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attrvalue = unescape(attrvalue)
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attrs.append((attrname.lower(), attrvalue))
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k = m.end()
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end = rawdata[k:endpos].strip()
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if end not in (">", "/>"):
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lineno, offset = self.getpos()
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if "\n" in self.__starttag_text:
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lineno = lineno + self.__starttag_text.count("\n")
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offset = len(self.__starttag_text) \
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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.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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else:
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self.handle_starttag(tag, attrs)
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if tag in self.CDATA_CONTENT_ELEMENTS:
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self.set_cdata_mode(tag)
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return endpos
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# Internal -- check to see if we have a complete starttag; return end
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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_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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if next == ">":
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return j + 1
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if next == "/":
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if rawdata.startswith("/>", j):
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return j + 2
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if rawdata.startswith("/", j):
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# buffer boundary
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return -1
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# else bogus input
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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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if next in ("abcdefghijklmnopqrstuvwxyz=/"
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"ABCDEFGHIJKLMNOPQRSTUVWXYZ"):
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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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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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def parse_endtag(self, i):
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rawdata = self.rawdata
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assert rawdata[i:i+2] == "</", "unexpected call to parse_endtag"
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match = endendtag.search(rawdata, i+1) # >
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if not match:
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return -1
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gtpos = match.end()
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match = endtagfind.match(rawdata, i) # </ + tag + >
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if not match:
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if self.cdata_elem is not None:
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self.handle_data(rawdata[i:gtpos])
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return gtpos
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# find the name: w3.org/TR/html5/tokenization.html#tag-name-state
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namematch = tagfind_tolerant.match(rawdata, i+2)
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if not namematch:
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# w3.org/TR/html5/tokenization.html#end-tag-open-state
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if rawdata[i:i+3] == '</>':
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return i+3
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else:
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return self.parse_bogus_comment(i)
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tagname = namematch.group(1).lower()
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# consume and ignore other stuff between the name and the >
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# Note: this is not 100% correct, since we might have things like
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# </tag attr=">">, but looking for > after tha name should cover
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# most of the cases and is much simpler
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gtpos = rawdata.find('>', namematch.end())
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self.handle_endtag(tagname)
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return gtpos+1
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elem = match.group(1).lower() # script or style
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if self.cdata_elem is not None:
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if elem != self.cdata_elem:
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self.handle_data(rawdata[i:gtpos])
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return gtpos
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self.handle_endtag(elem)
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self.clear_cdata_mode()
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return gtpos
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# Overridable -- finish processing of start+end tag: <tag.../>
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def handle_startendtag(self, tag, attrs):
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self.handle_starttag(tag, attrs)
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self.handle_endtag(tag)
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# Overridable -- handle start tag
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def handle_starttag(self, tag, attrs):
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pass
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# Overridable -- handle end tag
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def handle_endtag(self, tag):
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pass
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# Overridable -- handle character reference
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def handle_charref(self, name):
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pass
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# Overridable -- handle entity reference
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def handle_entityref(self, name):
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pass
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# Overridable -- handle data
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def handle_data(self, data):
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pass
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# Overridable -- handle comment
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def handle_comment(self, data):
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pass
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# Overridable -- handle declaration
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def handle_decl(self, decl):
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pass
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# Overridable -- handle processing instruction
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def handle_pi(self, data):
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pass
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def unknown_decl(self, data):
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pass
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