"""A parser for HTML and XHTML.""" | |
# This file is based on sgmllib.py, but the API is slightly different. | |
# XXX There should be a way to distinguish between PCDATA (parsed | |
# character data -- the normal case), RCDATA (replaceable character | |
# data -- only char and entity references and end tags are special) | |
# and CDATA (character data -- only end tags are special). | |
import markupbase | |
import re | |
# Regular expressions used for parsing | |
interesting_normal = re.compile('[&<]') | |
interesting_cdata = re.compile(r'<(/|\Z)') | |
incomplete = re.compile('&[a-zA-Z#]') | |
entityref = re.compile('&([a-zA-Z][-.a-zA-Z0-9]*)[^a-zA-Z0-9]') | |
charref = re.compile('&#(?:[0-9]+|[xX][0-9a-fA-F]+)[^0-9a-fA-F]') | |
starttagopen = re.compile('<[a-zA-Z]') | |
piclose = re.compile('>') | |
commentclose = re.compile(r'--\s*>') | |
tagfind = re.compile('[a-zA-Z][-.a-zA-Z0-9:_]*') | |
attrfind = re.compile( | |
r'\s*([a-zA-Z_][-.:a-zA-Z_0-9]*)(\s*=\s*' | |
r'(\'[^\']*\'|"[^"]*"|[^\s"\'=<>`]*))?') | |
locatestarttagend = re.compile(r""" | |
<[a-zA-Z][-.a-zA-Z0-9:_]* # tag name | |
(?:\s+ # whitespace before attribute name | |
(?:[a-zA-Z_][-.:a-zA-Z0-9_]* # attribute name | |
(?:\s*=\s* # value indicator | |
(?:'[^']*' # LITA-enclosed value | |
|\"[^\"]*\" # LIT-enclosed value | |
|[^'\">\s]+ # bare value | |
) | |
)? | |
) | |
)* | |
\s* # trailing whitespace | |
""", re.VERBOSE) | |
endendtag = re.compile('>') | |
endtagfind = re.compile('</\s*([a-zA-Z][-.a-zA-Z0-9:_]*)\s*>') | |
class HTMLParseError(Exception): | |
"""Exception raised for all parse errors.""" | |
def __init__(self, msg, position=(None, None)): | |
assert msg | |
self.msg = msg | |
self.lineno = position[0] | |
self.offset = position[1] | |
def __str__(self): | |
result = self.msg | |
if self.lineno is not None: | |
result = result + ", at line %d" % self.lineno | |
if self.offset is not None: | |
result = result + ", column %d" % (self.offset + 1) | |
return result | |
class HTMLParser(markupbase.ParserBase): | |
"""Find tags and other markup and call handler functions. | |
Usage: | |
p = HTMLParser() | |
p.feed(data) | |
... | |
p.close() | |
Start tags are handled by calling self.handle_starttag() or | |
self.handle_startendtag(); end tags by self.handle_endtag(). The | |
data between tags is passed from the parser to the derived class | |
by calling self.handle_data() with the data as argument (the data | |
may be split up in arbitrary chunks). Entity references are | |
passed by calling self.handle_entityref() with the entity | |
reference as the argument. Numeric character references are | |
passed to self.handle_charref() with the string containing the | |
reference as the argument. | |
""" | |
CDATA_CONTENT_ELEMENTS = ("script", "style") | |
def __init__(self): | |
"""Initialize and reset this instance.""" | |
self.reset() | |
def reset(self): | |
"""Reset this instance. Loses all unprocessed data.""" | |
self.rawdata = '' | |
self.lasttag = '???' | |
self.interesting = interesting_normal | |
markupbase.ParserBase.reset(self) | |
def feed(self, data): | |
r"""Feed data to the parser. | |
Call this as often as you want, with as little or as much text | |
as you want (may include '\n'). | |
""" | |
self.rawdata = self.rawdata + data | |
self.goahead(0) | |
def close(self): | |
"""Handle any buffered data.""" | |
self.goahead(1) | |
def error(self, message): | |
raise HTMLParseError(message, self.getpos()) | |
__starttag_text = None | |
def get_starttag_text(self): | |
"""Return full source of start tag: '<...>'.""" | |
return self.__starttag_text | |
def set_cdata_mode(self): | |
self.interesting = interesting_cdata | |
def clear_cdata_mode(self): | |
self.interesting = interesting_normal | |
# Internal -- handle data as far as reasonable. May leave state | |
# and data to be processed by a subsequent call. If 'end' is | |
# true, force handling all data as if followed by EOF marker. | |
def goahead(self, end): | |
rawdata = self.rawdata | |
i = 0 | |
n = len(rawdata) | |
while i < n: | |
match = self.interesting.search(rawdata, i) # < or & | |
if match: | |
j = match.start() | |
else: | |
j = n | |
if i < j: self.handle_data(rawdata[i:j]) | |
i = self.updatepos(i, j) | |
if i == n: break | |
startswith = rawdata.startswith | |
if startswith('<', i): | |
if starttagopen.match(rawdata, i): # < + letter | |
k = self.parse_starttag(i) | |
elif startswith("</", i): | |
k = self.parse_endtag(i) | |
elif startswith("<!--", i): | |
k = self.parse_comment(i) | |
elif startswith("<?", i): | |
k = self.parse_pi(i) | |
elif startswith("<!", i): | |
k = self.parse_declaration(i) | |
elif (i + 1) < n: | |
self.handle_data("<") | |
k = i + 1 | |
else: | |
break | |
if k < 0: | |
if end: | |
self.error("EOF in middle of construct") | |
break | |
i = self.updatepos(i, k) | |
elif startswith("&#", i): | |
match = charref.match(rawdata, i) | |
if match: | |
name = match.group()[2:-1] | |
self.handle_charref(name) | |
k = match.end() | |
if not startswith(';', k-1): | |
k = k - 1 | |
i = self.updatepos(i, k) | |
continue | |
else: | |
if ";" in rawdata[i:]: #bail by consuming &# | |
self.handle_data(rawdata[0:2]) | |
i = self.updatepos(i, 2) | |
break | |
elif startswith('&', i): | |
match = entityref.match(rawdata, i) | |
if match: | |
name = match.group(1) | |
self.handle_entityref(name) | |
k = match.end() | |
if not startswith(';', k-1): | |
k = k - 1 | |
i = self.updatepos(i, k) | |
continue | |
match = incomplete.match(rawdata, i) | |
if match: | |
# match.group() will contain at least 2 chars | |
if end and match.group() == rawdata[i:]: | |
self.error("EOF in middle of entity or char ref") | |
# incomplete | |
break | |
elif (i + 1) < n: | |
# not the end of the buffer, and can't be confused | |
# with some other construct | |
self.handle_data("&") | |
i = self.updatepos(i, i + 1) | |
else: | |
break | |
else: | |
assert 0, "interesting.search() lied" | |
# end while | |
if end and i < n: | |
self.handle_data(rawdata[i:n]) | |
i = self.updatepos(i, n) | |
self.rawdata = rawdata[i:] | |
# Internal -- parse processing instr, return end or -1 if not terminated | |
def parse_pi(self, i): | |
rawdata = self.rawdata | |
assert rawdata[i:i+2] == '<?', 'unexpected call to parse_pi()' | |
match = piclose.search(rawdata, i+2) # > | |
if not match: | |
return -1 | |
j = match.start() | |
self.handle_pi(rawdata[i+2: j]) | |
j = match.end() | |
return j | |
# Internal -- handle starttag, return end or -1 if not terminated | |
def parse_starttag(self, i): | |
self.__starttag_text = None | |
endpos = self.check_for_whole_start_tag(i) | |
if endpos < 0: | |
return endpos | |
rawdata = self.rawdata | |
self.__starttag_text = rawdata[i:endpos] | |
# Now parse the data between i+1 and j into a tag and attrs | |
attrs = [] | |
match = tagfind.match(rawdata, i+1) | |
assert match, 'unexpected call to parse_starttag()' | |
k = match.end() | |
self.lasttag = tag = rawdata[i+1:k].lower() | |
while k < endpos: | |
m = attrfind.match(rawdata, k) | |
if not m: | |
break | |
attrname, rest, attrvalue = m.group(1, 2, 3) | |
if not rest: | |
attrvalue = None | |
elif attrvalue[:1] == '\'' == attrvalue[-1:] or \ | |
attrvalue[:1] == '"' == attrvalue[-1:]: | |
attrvalue = attrvalue[1:-1] | |
attrvalue = self.unescape(attrvalue) | |
attrs.append((attrname.lower(), attrvalue)) | |
k = m.end() | |
end = rawdata[k:endpos].strip() | |
if end not in (">", "/>"): | |
lineno, offset = self.getpos() | |
if "\n" in self.__starttag_text: | |
lineno = lineno + self.__starttag_text.count("\n") | |
offset = len(self.__starttag_text) \ | |
- self.__starttag_text.rfind("\n") | |
else: | |
offset = offset + len(self.__starttag_text) | |
self.error("junk characters in start tag: %r" | |
% (rawdata[k:endpos][:20],)) | |
if end.endswith('/>'): | |
# XHTML-style empty tag: <span attr="value" /> | |
self.handle_startendtag(tag, attrs) | |
else: | |
self.handle_starttag(tag, attrs) | |
if tag in self.CDATA_CONTENT_ELEMENTS: | |
self.set_cdata_mode() | |
return endpos | |
# Internal -- check to see if we have a complete starttag; return end | |
# or -1 if incomplete. | |
def check_for_whole_start_tag(self, i): | |
rawdata = self.rawdata | |
m = locatestarttagend.match(rawdata, i) | |
if m: | |
j = m.end() | |
next = rawdata[j:j+1] | |
if next == ">": | |
return j + 1 | |
if next == "/": | |
if rawdata.startswith("/>", j): | |
return j + 2 | |
if rawdata.startswith("/", j): | |
# buffer boundary | |
return -1 | |
# else bogus input | |
self.updatepos(i, j + 1) | |
self.error("malformed empty start tag") | |
if next == "": | |
# end of input | |
return -1 | |
if next in ("abcdefghijklmnopqrstuvwxyz=/" | |
"ABCDEFGHIJKLMNOPQRSTUVWXYZ"): | |
# end of input in or before attribute value, or we have the | |
# '/' from a '/>' ending | |
return -1 | |
self.updatepos(i, j) | |
self.error("malformed start tag") | |
raise AssertionError("we should not get here!") | |
# Internal -- parse endtag, return end or -1 if incomplete | |
def parse_endtag(self, i): | |
rawdata = self.rawdata | |
assert rawdata[i:i+2] == "</", "unexpected call to parse_endtag" | |
match = endendtag.search(rawdata, i+1) # > | |
if not match: | |
return -1 | |
j = match.end() | |
match = endtagfind.match(rawdata, i) # </ + tag + > | |
if not match: | |
self.error("bad end tag: %r" % (rawdata[i:j],)) | |
tag = match.group(1) | |
self.handle_endtag(tag.lower()) | |
self.clear_cdata_mode() | |
return j | |
# Overridable -- finish processing of start+end tag: <tag.../> | |
def handle_startendtag(self, tag, attrs): | |
self.handle_starttag(tag, attrs) | |
self.handle_endtag(tag) | |
# Overridable -- handle start tag | |
def handle_starttag(self, tag, attrs): | |
pass | |
# Overridable -- handle end tag | |
def handle_endtag(self, tag): | |
pass | |
# Overridable -- handle character reference | |
def handle_charref(self, name): | |
pass | |
# Overridable -- handle entity reference | |
def handle_entityref(self, name): | |
pass | |
# Overridable -- handle data | |
def handle_data(self, data): | |
pass | |
# Overridable -- handle comment | |
def handle_comment(self, data): | |
pass | |
# Overridable -- handle declaration | |
def handle_decl(self, decl): | |
pass | |
# Overridable -- handle processing instruction | |
def handle_pi(self, data): | |
pass | |
def unknown_decl(self, data): | |
self.error("unknown declaration: %r" % (data,)) | |
# Internal -- helper to remove special character quoting | |
entitydefs = None | |
def unescape(self, s): | |
if '&' not in s: | |
return s | |
def replaceEntities(s): | |
s = s.groups()[0] | |
try: | |
if s[0] == "#": | |
s = s[1:] | |
if s[0] in ['x','X']: | |
c = int(s[1:], 16) | |
else: | |
c = int(s) | |
return unichr(c) | |
except ValueError: | |
return '&#'+s+';' | |
else: | |
# Cannot use name2codepoint directly, because HTMLParser supports apos, | |
# which is not part of HTML 4 | |
import htmlentitydefs | |
if HTMLParser.entitydefs is None: | |
entitydefs = HTMLParser.entitydefs = {'apos':u"'"} | |
for k, v in htmlentitydefs.name2codepoint.iteritems(): | |
entitydefs[k] = unichr(v) | |
try: | |
return self.entitydefs[s] | |
except KeyError: | |
return '&'+s+';' | |
return re.sub(r"&(#?[xX]?(?:[0-9a-fA-F]+|\w{1,8}));", replaceEntities, s) |