529 lines
17 KiB
Python
529 lines
17 KiB
Python
"""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).
|
|
|
|
|
|
import re
|
|
import string
|
|
|
|
__all__ = ["SGMLParser"]
|
|
|
|
# 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]*)/([^/]*)/')
|
|
piopen = re.compile('<\?')
|
|
piclose = re.compile('>')
|
|
endtagopen = re.compile('</[<>a-zA-Z]')
|
|
endbracket = re.compile('[<>]')
|
|
special = re.compile('<![^<>]*>')
|
|
commentopen = 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'(\'[^\']*\'|"[^"]*"|[-a-zA-Z0-9./:;+*%?!&$\(\)_#=~\'"]*))?')
|
|
|
|
decldata = re.compile(r'[^>\'\"]+')
|
|
declstringlit = re.compile(r'(\'[^\']*\'|"[^"]*")\s*')
|
|
|
|
|
|
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:
|
|
|
|
# Interface -- initialize and reset this instance
|
|
def __init__(self, verbose=0):
|
|
self.verbose = verbose
|
|
self.reset()
|
|
|
|
# Interface -- reset this instance. Loses all unprocessed data
|
|
def reset(self):
|
|
self.rawdata = ''
|
|
self.stack = []
|
|
self.lasttag = '???'
|
|
self.nomoretags = 0
|
|
self.literal = 0
|
|
|
|
# For derived classes only -- enter literal mode (CDATA) till EOF
|
|
def setnomoretags(self):
|
|
self.nomoretags = self.literal = 1
|
|
|
|
# For derived classes only -- enter literal mode (CDATA)
|
|
def setliteral(self, *args):
|
|
self.literal = 1
|
|
|
|
# Interface -- 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().)
|
|
def feed(self, data):
|
|
self.rawdata = self.rawdata + data
|
|
self.goahead(0)
|
|
|
|
# Interface -- handle the remaining data
|
|
def close(self):
|
|
self.goahead(1)
|
|
|
|
# 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(0)
|
|
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 endtagopen.match(rawdata, i):
|
|
k = self.parse_endtag(i)
|
|
if k < 0: break
|
|
i = k
|
|
self.literal = 0
|
|
continue
|
|
if commentopen.match(rawdata, i):
|
|
if self.literal:
|
|
self.handle_data(rawdata[i])
|
|
i = i+1
|
|
continue
|
|
k = self.parse_comment(i)
|
|
if k < 0: break
|
|
i = i+k
|
|
continue
|
|
if piopen.match(rawdata, i):
|
|
if self.literal:
|
|
self.handle_data(rawdata[i])
|
|
i = i+1
|
|
continue
|
|
k = self.parse_pi(i)
|
|
if k < 0: break
|
|
i = i+k
|
|
continue
|
|
match = special.match(rawdata, i)
|
|
if match:
|
|
if self.literal:
|
|
self.handle_data(rawdata[i])
|
|
i = i+1
|
|
continue
|
|
# 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] == '&':
|
|
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:
|
|
raise SGMLParseError('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
|
|
|
|
# Internal -- parse comment, return length or -1 if not terminated
|
|
def parse_comment(self, i):
|
|
rawdata = self.rawdata
|
|
if rawdata[i:i+4] != '<!--':
|
|
raise SGMLParseError('unexpected call to parse_comment()')
|
|
match = commentclose.search(rawdata, i+4)
|
|
if not match:
|
|
return -1
|
|
j = match.start(0)
|
|
self.handle_comment(rawdata[i+4: j])
|
|
j = match.end(0)
|
|
return j-i
|
|
|
|
# Internal -- parse declaration.
|
|
def parse_declaration(self, i):
|
|
rawdata = self.rawdata
|
|
j = i + 2
|
|
n = len(rawdata)
|
|
while j < n:
|
|
c = rawdata[j:j+1]
|
|
if c == ">":
|
|
# end of declaration syntax
|
|
self.handle_decl(rawdata[i+2:j])
|
|
return j + 1
|
|
if c in "\"'":
|
|
m = declstringlit.match(rawdata, j)
|
|
if not m:
|
|
# incomplete or an error?
|
|
return -1
|
|
j = m.end()
|
|
else:
|
|
m = decldata.match(rawdata, j)
|
|
if not m:
|
|
# incomplete or an error?
|
|
return -1
|
|
j = m.end()
|
|
# end of buffer between tokens
|
|
return -1
|
|
|
|
# Internal -- parse processing instr, return length or -1 if not terminated
|
|
def parse_pi(self, i):
|
|
rawdata = self.rawdata
|
|
if rawdata[i:i+2] != '<?':
|
|
raise SGMLParseError('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
|
|
|
|
__starttag_text = None
|
|
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 ")
|
|
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:
|
|
raise SGMLParseError('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
|
|
elif attrvalue[:1] == '\'' == attrvalue[-1:] or \
|
|
attrvalue[:1] == '"' == attrvalue[-1:]:
|
|
attrvalue = attrvalue[1:-1]
|
|
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 -- 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
|
|
|
|
# Example -- handle character reference, no need to override
|
|
def handle_charref(self, name):
|
|
try:
|
|
n = int(name)
|
|
except ValueError:
|
|
self.unknown_charref(name)
|
|
return
|
|
if not 0 <= n <= 255:
|
|
self.unknown_charref(name)
|
|
return
|
|
self.handle_data(chr(n))
|
|
|
|
# Definition of entities -- derived classes may override
|
|
entitydefs = \
|
|
{'lt': '<', 'gt': '>', 'amp': '&', 'quot': '"', 'apos': '\''}
|
|
|
|
# Example -- handle entity reference, no need to override
|
|
def handle_entityref(self, name):
|
|
table = self.entitydefs
|
|
if table.has_key(name):
|
|
self.handle_data(table[name])
|
|
else:
|
|
self.unknown_entityref(name)
|
|
return
|
|
|
|
# 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(`self.testdata`) >= 70:
|
|
self.flush()
|
|
|
|
def flush(self):
|
|
data = self.testdata
|
|
if data:
|
|
self.testdata = ""
|
|
print 'data:', `data`
|
|
|
|
def handle_comment(self, data):
|
|
self.flush()
|
|
r = `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 close(self):
|
|
SGMLParser.close(self)
|
|
self.flush()
|
|
|
|
|
|
def test(args = None):
|
|
import sys
|
|
|
|
if not args:
|
|
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()
|