mirror of
https://github.com/python/cpython.git
synced 2024-11-24 17:47:13 +01:00
325 lines
8.7 KiB
Python
325 lines
8.7 KiB
Python
# A parser for SGML, using the derived class as 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 regex
|
|
import string
|
|
|
|
|
|
# Regular expressions used for parsing
|
|
|
|
incomplete = regex.compile(
|
|
'<!-?\|</[a-zA-Z][a-zA-Z0-9]*[ \t\n]*\|</?\|' +
|
|
'&#[a-zA-Z0-9]*\|&[a-zA-Z][a-zA-Z0-9]*\|&')
|
|
entityref = regex.compile('&[a-zA-Z][a-zA-Z0-9]*[;.]')
|
|
charref = regex.compile('&#[a-zA-Z0-9]+;')
|
|
starttagopen = regex.compile('<[a-zA-Z]')
|
|
endtag = regex.compile('</[a-zA-Z][a-zA-Z0-9]*[ \t\n]*>')
|
|
special = regex.compile('<![^<>]*>')
|
|
commentopen = regex.compile('<!--')
|
|
commentclose = regex.compile('--[ \t\n]*>')
|
|
|
|
|
|
# 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 arbutrary
|
|
# 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):
|
|
self.reset()
|
|
|
|
# Interface -- reset this instance. Loses all unprocessed data
|
|
def reset(self):
|
|
self.rawdata = ''
|
|
self.stack = []
|
|
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
|
|
j = incomplete.search(rawdata, i)
|
|
if j < 0: 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) >= 0:
|
|
if self.literal:
|
|
self.handle_data(rawdata[i])
|
|
i = i+1
|
|
continue
|
|
k = self.parse_starttag(i)
|
|
if k < 0: break
|
|
i = i + k
|
|
continue
|
|
k = endtag.match(rawdata, i)
|
|
if k >= 0:
|
|
j = i+k
|
|
self.parse_endtag(rawdata[i:j])
|
|
i = j
|
|
self.literal = 0
|
|
continue
|
|
if commentopen.match(rawdata, i) >= 0:
|
|
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
|
|
k = special.match(rawdata, i)
|
|
if k >= 0:
|
|
if self.literal:
|
|
self.handle_data(rawdata[i])
|
|
i = i+1
|
|
continue
|
|
i = i+k
|
|
continue
|
|
elif rawdata[i] == '&':
|
|
k = charref.match(rawdata, i)
|
|
if k >= 0:
|
|
j = i+k
|
|
self.handle_charref(rawdata[i+2:j-1])
|
|
i = j
|
|
continue
|
|
k = entityref.match(rawdata, i)
|
|
if k >= 0:
|
|
j = i+k
|
|
self.handle_entityref(rawdata[i+1:j-1])
|
|
i = j
|
|
continue
|
|
else:
|
|
raise RuntimeError, 'neither < nor & ??'
|
|
# We get here only if incomplete matches but
|
|
# nothing else
|
|
k = incomplete.match(rawdata, i)
|
|
if k < 0: raise RuntimeError, 'no incomplete match ??'
|
|
j = i+k
|
|
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 RuntimeError, 'unexpected call to handle_comment'
|
|
j = commentclose.search(rawdata, i+4)
|
|
if j < 0:
|
|
return -1
|
|
self.handle_comment(rawdata[i+4: j])
|
|
j = j+commentclose.match(rawdata, j)
|
|
return j-i
|
|
|
|
# Internal -- handle starttag, return length or -1 if not terminated
|
|
def parse_starttag(self, i):
|
|
rawdata = self.rawdata
|
|
try:
|
|
j = string.index(rawdata, '>', i)
|
|
except string.index_error:
|
|
return -1
|
|
# Now parse the data between i+1 and j into a tag and attrs
|
|
attrs = []
|
|
tagfind = regex.compile('[a-zA-Z][a-zA-Z0-9]*')
|
|
attrfind = regex.compile(
|
|
'[ \t\n]+\([a-zA-Z][a-zA-Z0-9]*\)' +
|
|
'\([ \t\n]*=[ \t\n]*' +
|
|
'\(\'[^\']*\';\|"[^"]*"\|[-a-zA-Z0-9./:+*%?!()_#]+\)\)?')
|
|
k = tagfind.match(rawdata, i+1)
|
|
if k < 0:
|
|
raise RuntimeError, 'unexpected call to parse_starttag'
|
|
k = i+1+k
|
|
tag = string.lower(rawdata[i+1:k])
|
|
while k < j:
|
|
l = attrfind.match(rawdata, k)
|
|
if l < 0: break
|
|
attrname, rest, attrvalue = attrfind.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((string.lower(attrname), attrvalue))
|
|
k = k + l
|
|
j = j+1
|
|
try:
|
|
method = getattr(self, 'start_' + tag)
|
|
except AttributeError:
|
|
try:
|
|
method = getattr(self, 'do_' + tag)
|
|
except AttributeError:
|
|
self.unknown_starttag(tag, attrs)
|
|
return j-i
|
|
method(attrs)
|
|
return j-i
|
|
self.stack.append(tag)
|
|
method(attrs)
|
|
return j-i
|
|
|
|
# Internal -- parse endtag
|
|
def parse_endtag(self, data):
|
|
if data[:2] <> '</' or data[-1:] <> '>':
|
|
raise RuntimeError, 'unexpected call to parse_endtag'
|
|
tag = string.lower(string.strip(data[2:-1]))
|
|
try:
|
|
method = getattr(self, 'end_' + tag)
|
|
except AttributeError:
|
|
self.unknown_endtag(tag)
|
|
return
|
|
# XXX Should invoke end methods when popping their
|
|
# XXX stack entry, not when encountering the tag!
|
|
if self.stack and self.stack[-1] == tag:
|
|
del self.stack[-1]
|
|
else:
|
|
self.report_unbalanced(tag)
|
|
# Now repair it
|
|
found = None
|
|
for i in range(len(self.stack)):
|
|
if self.stack[i] == tag: found = i
|
|
if found <> None:
|
|
del self.stack[found:]
|
|
method()
|
|
|
|
# Example -- report an unbalanced </...> tag.
|
|
def report_unbalanced(self, tag):
|
|
print '*** Unbalanced </' + tag + '>'
|
|
print '*** Stack:', self.stack
|
|
|
|
# Example -- handle character reference, no need to override
|
|
def handle_charref(self, name):
|
|
try:
|
|
n = string.atoi(name)
|
|
except string.atoi_error:
|
|
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
|
|
name = string.lower(name)
|
|
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
|
|
|
|
# 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 TestSGML(SGMLParser):
|
|
|
|
def handle_data(self, data):
|
|
r = repr(data)
|
|
if len(r) > 72:
|
|
r = r[:35] + '...' + r[-35:]
|
|
print 'data:', r
|
|
|
|
def handle_comment(self, data):
|
|
r = repr(data)
|
|
if len(r) > 68:
|
|
r = r[:32] + '...' + r[-32:]
|
|
print 'comment:', r
|
|
|
|
def unknown_starttag(self, tag, attrs):
|
|
print 'start tag: <' + tag,
|
|
for name, value in attrs:
|
|
print name + '=' + '"' + value + '"',
|
|
print '>'
|
|
|
|
def unknown_endtag(self, tag):
|
|
print 'end tag: </' + tag + '>'
|
|
|
|
def unknown_entityref(self, ref):
|
|
print '*** unknown entity ref: &' + ref + ';'
|
|
|
|
def unknown_charref(self, ref):
|
|
print '*** unknown char ref: &#' + ref + ';'
|
|
|
|
|
|
def test():
|
|
file = 'test.html'
|
|
f = open(file, 'r')
|
|
x = TestSGML()
|
|
while 1:
|
|
line = f.readline()
|
|
if not line:
|
|
x.close()
|
|
break
|
|
x.feed(line)
|
|
|
|
|
|
if __name__ == '__main__':
|
|
test()
|