"""A parser for SGML, using the derived class as a static DTD.""" | |
# XXX This only supports those SGML features used by HTML. | |
# 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). RCDATA is | |
# not supported at all. | |
from warnings import warnpy3k | |
warnpy3k("the sgmllib module has been removed in Python 3.0", | |
stacklevel=2) | |
del warnpy3k | |
import markupbase | |
import re | |
__all__ = ["SGMLParser", "SGMLParseError"] | |
# Regular expressions used for parsing | |
interesting = re.compile('[&<]') | |
incomplete = re.compile('&([a-zA-Z][a-zA-Z0-9]*|#[0-9]*)?|' | |
'<([a-zA-Z][^<>]*|' | |
'/([a-zA-Z][^<>]*)?|' | |
'![^<>]*)?') | |
entityref = re.compile('&([a-zA-Z][-.a-zA-Z0-9]*)[^a-zA-Z0-9]') | |
charref = re.compile('&#([0-9]+)[^0-9]') | |
starttagopen = re.compile('<[>a-zA-Z]') | |
shorttagopen = re.compile('<[a-zA-Z][-.a-zA-Z0-9]*/') | |
shorttag = re.compile('<([a-zA-Z][-.a-zA-Z0-9]*)/([^/]*)/') | |
piclose = re.compile('>') | |
endbracket = re.compile('[<>]') | |
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'(\'[^\']*\'|"[^"]*"|[][\-a-zA-Z0-9./,:;+*%?!&$\(\)_#=~\'"@]*))?') | |
class SGMLParseError(RuntimeError): | |
"""Exception raised for all parse errors.""" | |
pass | |
# SGML parser base class -- find tags and call handler functions. | |
# Usage: p = SGMLParser(); p.feed(data); ...; p.close(). | |
# The dtd is defined by deriving a class which defines methods | |
# with special names to handle tags: start_foo and end_foo to handle | |
# <foo> and </foo>, respectively, or do_foo to handle <foo> by itself. | |
# (Tags are converted to lower case for this purpose.) The data | |
# between tags is passed to the parser by calling self.handle_data() | |
# with some 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 argument. | |
class SGMLParser(markupbase.ParserBase): | |
# Definition of entities -- derived classes may override | |
entity_or_charref = re.compile('&(?:' | |
'([a-zA-Z][-.a-zA-Z0-9]*)|#([0-9]+)' | |
')(;?)') | |
def __init__(self, verbose=0): | |
"""Initialize and reset this instance.""" | |
self.verbose = verbose | |
self.reset() | |
def reset(self): | |
"""Reset this instance. Loses all unprocessed data.""" | |
self.__starttag_text = None | |
self.rawdata = '' | |
self.stack = [] | |
self.lasttag = '???' | |
self.nomoretags = 0 | |
self.literal = 0 | |
markupbase.ParserBase.reset(self) | |
def setnomoretags(self): | |
"""Enter literal mode (CDATA) till EOF. | |
Intended for derived classes only. | |
""" | |
self.nomoretags = self.literal = 1 | |
def setliteral(self, *args): | |
"""Enter literal mode (CDATA). | |
Intended for derived classes only. | |
""" | |
self.literal = 1 | |
def feed(self, data): | |
"""Feed some data to the parser. | |
Call this as often as you want, with as little or as much text | |
as you want (may include '\n'). (This just saves the text, | |
all the processing is done by goahead().) | |
""" | |
self.rawdata = self.rawdata + data | |
self.goahead(0) | |
def close(self): | |
"""Handle the remaining data.""" | |
self.goahead(1) | |
def error(self, message): | |
raise SGMLParseError(message) | |
# 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: | |
if self.nomoretags: | |
self.handle_data(rawdata[i:n]) | |
i = n | |
break | |
match = interesting.search(rawdata, i) | |
if match: j = match.start() | |
else: j = n | |
if i < j: | |
self.handle_data(rawdata[i:j]) | |
i = j | |
if i == n: break | |
if rawdata[i] == '<': | |
if starttagopen.match(rawdata, i): | |
if self.literal: | |
self.handle_data(rawdata[i]) | |
i = i+1 | |
continue | |
k = self.parse_starttag(i) | |
if k < 0: break | |
i = k | |
continue | |
if rawdata.startswith("</", i): | |
k = self.parse_endtag(i) | |
if k < 0: break | |
i = k | |
self.literal = 0 | |
continue | |
if self.literal: | |
if n > (i + 1): | |
self.handle_data("<") | |
i = i+1 | |
else: | |
# incomplete | |
break | |
continue | |
if rawdata.startswith("<!--", i): | |
# Strictly speaking, a comment is --.*-- | |
# within a declaration tag <!...>. | |
# This should be removed, | |
# and comments handled only in parse_declaration. | |
k = self.parse_comment(i) | |
if k < 0: break | |
i = k | |
continue | |
if rawdata.startswith("<?", i): | |
k = self.parse_pi(i) | |
if k < 0: break | |
i = i+k | |
continue | |
if rawdata.startswith("<!", i): | |
# This is some sort of declaration; in "HTML as | |
# deployed," this should only be the document type | |
# declaration ("<!DOCTYPE html...>"). | |
k = self.parse_declaration(i) | |
if k < 0: break | |
i = k | |
continue | |
elif rawdata[i] == '&': | |
if self.literal: | |
self.handle_data(rawdata[i]) | |
i = i+1 | |
continue | |
match = charref.match(rawdata, i) | |
if match: | |
name = match.group(1) | |
self.handle_charref(name) | |
i = match.end(0) | |
if rawdata[i-1] != ';': i = i-1 | |
continue | |
match = entityref.match(rawdata, i) | |
if match: | |
name = match.group(1) | |
self.handle_entityref(name) | |
i = match.end(0) | |
if rawdata[i-1] != ';': i = i-1 | |
continue | |
else: | |
self.error('neither < nor & ??') | |
# We get here only if incomplete matches but | |
# nothing else | |
match = incomplete.match(rawdata, i) | |
if not match: | |
self.handle_data(rawdata[i]) | |
i = i+1 | |
continue | |
j = match.end(0) | |
if j == n: | |
break # Really incomplete | |
self.handle_data(rawdata[i:j]) | |
i = j | |
# end while | |
if end and i < n: | |
self.handle_data(rawdata[i:n]) | |
i = n | |
self.rawdata = rawdata[i:] | |
# XXX if end: check for empty stack | |
# Extensions for the DOCTYPE scanner: | |
_decl_otherchars = '=' | |
# Internal -- parse processing instr, return length or -1 if not terminated | |
def parse_pi(self, i): | |
rawdata = self.rawdata | |
if rawdata[i:i+2] != '<?': | |
self.error('unexpected call to parse_pi()') | |
match = piclose.search(rawdata, i+2) | |
if not match: | |
return -1 | |
j = match.start(0) | |
self.handle_pi(rawdata[i+2: j]) | |
j = match.end(0) | |
return j-i | |
def get_starttag_text(self): | |
return self.__starttag_text | |
# Internal -- handle starttag, return length or -1 if not terminated | |
def parse_starttag(self, i): | |
self.__starttag_text = None | |
start_pos = i | |
rawdata = self.rawdata | |
if shorttagopen.match(rawdata, i): | |
# SGML shorthand: <tag/data/ == <tag>data</tag> | |
# XXX Can data contain &... (entity or char refs)? | |
# XXX Can data contain < or > (tag characters)? | |
# XXX Can there be whitespace before the first /? | |
match = shorttag.match(rawdata, i) | |
if not match: | |
return -1 | |
tag, data = match.group(1, 2) | |
self.__starttag_text = '<%s/' % tag | |
tag = tag.lower() | |
k = match.end(0) | |
self.finish_shorttag(tag, data) | |
self.__starttag_text = rawdata[start_pos:match.end(1) + 1] | |
return k | |
# XXX The following should skip matching quotes (' or ") | |
# As a shortcut way to exit, this isn't so bad, but shouldn't | |
# be used to locate the actual end of the start tag since the | |
# < or > characters may be embedded in an attribute value. | |
match = endbracket.search(rawdata, i+1) | |
if not match: | |
return -1 | |
j = match.start(0) | |
# Now parse the data between i+1 and j into a tag and attrs | |
attrs = [] | |
if rawdata[i:i+2] == '<>': | |
# SGML shorthand: <> == <last open tag seen> | |
k = j | |
tag = self.lasttag | |
else: | |
match = tagfind.match(rawdata, i+1) | |
if not match: | |
self.error('unexpected call to parse_starttag') | |
k = match.end(0) | |
tag = rawdata[i+1:k].lower() | |
self.lasttag = tag | |
while k < j: | |
match = attrfind.match(rawdata, k) | |
if not match: break | |
attrname, rest, attrvalue = match.group(1, 2, 3) | |
if not rest: | |
attrvalue = attrname | |
else: | |
if (attrvalue[:1] == "'" == attrvalue[-1:] or | |
attrvalue[:1] == '"' == attrvalue[-1:]): | |
# strip quotes | |
attrvalue = attrvalue[1:-1] | |
attrvalue = self.entity_or_charref.sub( | |
self._convert_ref, attrvalue) | |
attrs.append((attrname.lower(), attrvalue)) | |
k = match.end(0) | |
if rawdata[j] == '>': | |
j = j+1 | |
self.__starttag_text = rawdata[start_pos:j] | |
self.finish_starttag(tag, attrs) | |
return j | |
# Internal -- convert entity or character reference | |
def _convert_ref(self, match): | |
if match.group(2): | |
return self.convert_charref(match.group(2)) or \ | |
'&#%s%s' % match.groups()[1:] | |
elif match.group(3): | |
return self.convert_entityref(match.group(1)) or \ | |
'&%s;' % match.group(1) | |
else: | |
return '&%s' % match.group(1) | |
# Internal -- parse endtag | |
def parse_endtag(self, i): | |
rawdata = self.rawdata | |
match = endbracket.search(rawdata, i+1) | |
if not match: | |
return -1 | |
j = match.start(0) | |
tag = rawdata[i+2:j].strip().lower() | |
if rawdata[j] == '>': | |
j = j+1 | |
self.finish_endtag(tag) | |
return j | |
# Internal -- finish parsing of <tag/data/ (same as <tag>data</tag>) | |
def finish_shorttag(self, tag, data): | |
self.finish_starttag(tag, []) | |
self.handle_data(data) | |
self.finish_endtag(tag) | |
# Internal -- finish processing of start tag | |
# Return -1 for unknown tag, 0 for open-only tag, 1 for balanced tag | |
def finish_starttag(self, tag, attrs): | |
try: | |
method = getattr(self, 'start_' + tag) | |
except AttributeError: | |
try: | |
method = getattr(self, 'do_' + tag) | |
except AttributeError: | |
self.unknown_starttag(tag, attrs) | |
return -1 | |
else: | |
self.handle_starttag(tag, method, attrs) | |
return 0 | |
else: | |
self.stack.append(tag) | |
self.handle_starttag(tag, method, attrs) | |
return 1 | |
# Internal -- finish processing of end tag | |
def finish_endtag(self, tag): | |
if not tag: | |
found = len(self.stack) - 1 | |
if found < 0: | |
self.unknown_endtag(tag) | |
return | |
else: | |
if tag not in self.stack: | |
try: | |
method = getattr(self, 'end_' + tag) | |
except AttributeError: | |
self.unknown_endtag(tag) | |
else: | |
self.report_unbalanced(tag) | |
return | |
found = len(self.stack) | |
for i in range(found): | |
if self.stack[i] == tag: found = i | |
while len(self.stack) > found: | |
tag = self.stack[-1] | |
try: | |
method = getattr(self, 'end_' + tag) | |
except AttributeError: | |
method = None | |
if method: | |
self.handle_endtag(tag, method) | |
else: | |
self.unknown_endtag(tag) | |
del self.stack[-1] | |
# Overridable -- handle start tag | |
def handle_starttag(self, tag, method, attrs): | |
method(attrs) | |
# Overridable -- handle end tag | |
def handle_endtag(self, tag, method): | |
method() | |
# Example -- report an unbalanced </...> tag. | |
def report_unbalanced(self, tag): | |
if self.verbose: | |
print '*** Unbalanced </' + tag + '>' | |
print '*** Stack:', self.stack | |
def convert_charref(self, name): | |
"""Convert character reference, may be overridden.""" | |
try: | |
n = int(name) | |
except ValueError: | |
return | |
if not 0 <= n <= 127: | |
return | |
return self.convert_codepoint(n) | |
def convert_codepoint(self, codepoint): | |
return chr(codepoint) | |
def handle_charref(self, name): | |
"""Handle character reference, no need to override.""" | |
replacement = self.convert_charref(name) | |
if replacement is None: | |
self.unknown_charref(name) | |
else: | |
self.handle_data(replacement) | |
# Definition of entities -- derived classes may override | |
entitydefs = \ | |
{'lt': '<', 'gt': '>', 'amp': '&', 'quot': '"', 'apos': '\''} | |
def convert_entityref(self, name): | |
"""Convert entity references. | |
As an alternative to overriding this method; one can tailor the | |
results by setting up the self.entitydefs mapping appropriately. | |
""" | |
table = self.entitydefs | |
if name in table: | |
return table[name] | |
else: | |
return | |
def handle_entityref(self, name): | |
"""Handle entity references, no need to override.""" | |
replacement = self.convert_entityref(name) | |
if replacement is None: | |
self.unknown_entityref(name) | |
else: | |
self.handle_data(replacement) | |
# Example -- handle data, should be overridden | |
def handle_data(self, data): | |
pass | |
# Example -- handle comment, could be overridden | |
def handle_comment(self, data): | |
pass | |
# Example -- handle declaration, could be overridden | |
def handle_decl(self, decl): | |
pass | |
# Example -- handle processing instruction, could be overridden | |
def handle_pi(self, data): | |
pass | |
# To be overridden -- handlers for unknown objects | |
def unknown_starttag(self, tag, attrs): pass | |
def unknown_endtag(self, tag): pass | |
def unknown_charref(self, ref): pass | |
def unknown_entityref(self, ref): pass | |
class TestSGMLParser(SGMLParser): | |
def __init__(self, verbose=0): | |
self.testdata = "" | |
SGMLParser.__init__(self, verbose) | |
def handle_data(self, data): | |
self.testdata = self.testdata + data | |
if len(repr(self.testdata)) >= 70: | |
self.flush() | |
def flush(self): | |
data = self.testdata | |
if data: | |
self.testdata = "" | |
print 'data:', repr(data) | |
def handle_comment(self, data): | |
self.flush() | |
r = repr(data) | |
if len(r) > 68: | |
r = r[:32] + '...' + r[-32:] | |
print 'comment:', r | |
def unknown_starttag(self, tag, attrs): | |
self.flush() | |
if not attrs: | |
print 'start tag: <' + tag + '>' | |
else: | |
print 'start tag: <' + tag, | |
for name, value in attrs: | |
print name + '=' + '"' + value + '"', | |
print '>' | |
def unknown_endtag(self, tag): | |
self.flush() | |
print 'end tag: </' + tag + '>' | |
def unknown_entityref(self, ref): | |
self.flush() | |
print '*** unknown entity ref: &' + ref + ';' | |
def unknown_charref(self, ref): | |
self.flush() | |
print '*** unknown char ref: &#' + ref + ';' | |
def unknown_decl(self, data): | |
self.flush() | |
print '*** unknown decl: [' + data + ']' | |
def close(self): | |
SGMLParser.close(self) | |
self.flush() | |
def test(args = None): | |
import sys | |
if args is None: | |
args = sys.argv[1:] | |
if args and args[0] == '-s': | |
args = args[1:] | |
klass = SGMLParser | |
else: | |
klass = TestSGMLParser | |
if args: | |
file = args[0] | |
else: | |
file = 'test.html' | |
if file == '-': | |
f = sys.stdin | |
else: | |
try: | |
f = open(file, 'r') | |
except IOError, msg: | |
print file, ":", msg | |
sys.exit(1) | |
data = f.read() | |
if f is not sys.stdin: | |
f.close() | |
x = klass() | |
for c in data: | |
x.feed(c) | |
x.close() | |
if __name__ == '__main__': | |
test() |