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382 lines
13 KiB
382 lines
13 KiB
"""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 markupbase |
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import re |
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# Regular expressions used for parsing |
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interesting_normal = re.compile('[&<]') |
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interesting_cdata = re.compile(r'<(/|\Z)') |
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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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tagfind = re.compile('[a-zA-Z][-.a-zA-Z0-9:_]*') |
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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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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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(?:[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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)? |
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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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class HTMLParseError(Exception): |
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"""Exception raised for all parse errors.""" |
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def __init__(self, msg, position=(None, None)): |
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assert msg |
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self.msg = msg |
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self.lineno = position[0] |
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self.offset = position[1] |
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def __str__(self): |
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result = self.msg |
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if self.lineno is not None: |
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result = result + ", at line %d" % self.lineno |
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if self.offset is not None: |
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result = result + ", column %d" % (self.offset + 1) |
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return result |
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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). Entity references are |
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passed by calling self.handle_entityref() with the entity |
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reference as the argument. Numeric character references are |
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passed to self.handle_charref() with the string containing the |
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reference as the argument. |
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""" |
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CDATA_CONTENT_ELEMENTS = ("script", "style") |
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def __init__(self): |
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"""Initialize and reset this instance.""" |
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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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markupbase.ParserBase.reset(self) |
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def feed(self, data): |
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"""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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def error(self, message): |
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raise HTMLParseError(message, self.getpos()) |
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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): |
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self.interesting = interesting_cdata |
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def clear_cdata_mode(self): |
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self.interesting = interesting_normal |
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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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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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j = n |
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if i < j: 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_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 end: |
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self.error("EOF in middle of construct") |
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break |
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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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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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self.error("EOF in middle of entity or char ref") |
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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: |
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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 comment, return end or -1 if not terminated |
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def parse_comment(self, i, report=1): |
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rawdata = self.rawdata |
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assert rawdata[i:i+4] == '<!--', 'unexpected call to parse_comment()' |
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match = commentclose.search(rawdata, i+4) |
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if not match: |
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return -1 |
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if report: |
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j = match.start() |
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self.handle_comment(rawdata[i+4: j]) |
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j = match.end() |
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return j |
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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.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 = 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 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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attrvalue = self.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.error("junk characters in start tag: %s" |
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% `rawdata[k:endpos][:20]`) |
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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() |
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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.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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self.updatepos(i, j + 1) |
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self.error("malformed empty start tag") |
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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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self.updatepos(i, j) |
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self.error("malformed start tag") |
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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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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: %s" % `rawdata[i: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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return j |
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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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self.error("unknown declaration: " + `data`) |
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# Internal -- helper to remove special character quoting |
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def unescape(self, s): |
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if '&' not in s: |
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return s |
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s = s.replace("<", "<") |
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s = s.replace(">", ">") |
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s = s.replace("'", "'") |
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s = s.replace(""", '"') |
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s = s.replace("&", "&") # Must be last |
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return s
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