|
Line 0
Link Here
|
|
|
1 |
"""A parser for SGML, using the derived class as a static DTD.""" |
| 2 |
|
| 3 |
# XXX This only supports those SGML features used by HTML. |
| 4 |
|
| 5 |
# XXX There should be a way to distinguish between PCDATA (parsed |
| 6 |
# character data -- the normal case), RCDATA (replaceable character |
| 7 |
# data -- only char and entity references and end tags are special) |
| 8 |
# and CDATA (character data -- only end tags are special). RCDATA is |
| 9 |
# not supported at all. |
| 10 |
|
| 11 |
import _markupbase |
| 12 |
import re |
| 13 |
|
| 14 |
__all__ = ["SGMLParser", "SGMLParseError"] |
| 15 |
|
| 16 |
# Regular expressions used for parsing |
| 17 |
|
| 18 |
interesting = re.compile('[&<]') |
| 19 |
incomplete = re.compile('&([a-zA-Z][a-zA-Z0-9]*|#[0-9]*)?|' |
| 20 |
'<([a-zA-Z][^<>]*|' |
| 21 |
'/([a-zA-Z][^<>]*)?|' |
| 22 |
'![^<>]*)?') |
| 23 |
|
| 24 |
entityref = re.compile('&([a-zA-Z][-.a-zA-Z0-9]*)[^a-zA-Z0-9]') |
| 25 |
charref = re.compile('&#([0-9]+)[^0-9]') |
| 26 |
|
| 27 |
starttagopen = re.compile('<[>a-zA-Z]') |
| 28 |
shorttagopen = re.compile('<[a-zA-Z][-.a-zA-Z0-9]*/') |
| 29 |
shorttag = re.compile('<([a-zA-Z][-.a-zA-Z0-9]*)/([^/]*)/') |
| 30 |
piclose = re.compile('>') |
| 31 |
endbracket = re.compile('[<>]') |
| 32 |
tagfind = re.compile('[a-zA-Z][-_.a-zA-Z0-9]*') |
| 33 |
attrfind = re.compile( |
| 34 |
r'\s*([a-zA-Z_][-:.a-zA-Z_0-9]*)(\s*=\s*' |
| 35 |
r'(\'[^\']*\'|"[^"]*"|[][\-a-zA-Z0-9./,:;+*%?!&$\(\)_#=~\'"@]*))?') |
| 36 |
|
| 37 |
|
| 38 |
class SGMLParseError(RuntimeError): |
| 39 |
"""Exception raised for all parse errors.""" |
| 40 |
pass |
| 41 |
|
| 42 |
|
| 43 |
# SGML parser base class -- find tags and call handler functions. |
| 44 |
# Usage: p = SGMLParser(); p.feed(data); ...; p.close(). |
| 45 |
# The dtd is defined by deriving a class which defines methods |
| 46 |
# with special names to handle tags: start_foo and end_foo to handle |
| 47 |
# <foo> and </foo>, respectively, or do_foo to handle <foo> by itself. |
| 48 |
# (Tags are converted to lower case for this purpose.) The data |
| 49 |
# between tags is passed to the parser by calling self.handle_data() |
| 50 |
# with some data as argument (the data may be split up in arbitrary |
| 51 |
# chunks). Entity references are passed by calling |
| 52 |
# self.handle_entityref() with the entity reference as argument. |
| 53 |
|
| 54 |
class SGMLParser(_markupbase.ParserBase): |
| 55 |
# Definition of entities -- derived classes may override |
| 56 |
entity_or_charref = re.compile('&(?:' |
| 57 |
'([a-zA-Z][-.a-zA-Z0-9]*)|#([0-9]+)' |
| 58 |
')(;?)') |
| 59 |
|
| 60 |
def __init__(self, verbose=0): |
| 61 |
"""Initialize and reset this instance.""" |
| 62 |
self.verbose = verbose |
| 63 |
self.reset() |
| 64 |
|
| 65 |
def reset(self): |
| 66 |
"""Reset this instance. Loses all unprocessed data.""" |
| 67 |
self.__starttag_text = None |
| 68 |
self.rawdata = '' |
| 69 |
self.stack = [] |
| 70 |
self.lasttag = '???' |
| 71 |
self.nomoretags = 0 |
| 72 |
self.literal = 0 |
| 73 |
_markupbase.ParserBase.reset(self) |
| 74 |
|
| 75 |
def setnomoretags(self): |
| 76 |
"""Enter literal mode (CDATA) till EOF. |
| 77 |
|
| 78 |
Intended for derived classes only. |
| 79 |
""" |
| 80 |
self.nomoretags = self.literal = 1 |
| 81 |
|
| 82 |
def setliteral(self, *args): |
| 83 |
"""Enter literal mode (CDATA). |
| 84 |
|
| 85 |
Intended for derived classes only. |
| 86 |
""" |
| 87 |
self.literal = 1 |
| 88 |
|
| 89 |
def feed(self, data): |
| 90 |
"""Feed some data to the parser. |
| 91 |
|
| 92 |
Call this as often as you want, with as little or as much text |
| 93 |
as you want (may include '\n'). (This just saves the text, |
| 94 |
all the processing is done by goahead().) |
| 95 |
""" |
| 96 |
|
| 97 |
self.rawdata = self.rawdata + data |
| 98 |
self.goahead(0) |
| 99 |
|
| 100 |
def close(self): |
| 101 |
"""Handle the remaining data.""" |
| 102 |
self.goahead(1) |
| 103 |
|
| 104 |
def error(self, message): |
| 105 |
raise SGMLParseError(message) |
| 106 |
|
| 107 |
# Internal -- handle data as far as reasonable. May leave state |
| 108 |
# and data to be processed by a subsequent call. If 'end' is |
| 109 |
# true, force handling all data as if followed by EOF marker. |
| 110 |
def goahead(self, end): |
| 111 |
rawdata = self.rawdata |
| 112 |
i = 0 |
| 113 |
n = len(rawdata) |
| 114 |
while i < n: |
| 115 |
if self.nomoretags: |
| 116 |
self.handle_data(rawdata[i:n]) |
| 117 |
i = n |
| 118 |
break |
| 119 |
match = interesting.search(rawdata, i) |
| 120 |
if match: j = match.start() |
| 121 |
else: j = n |
| 122 |
if i < j: |
| 123 |
self.handle_data(rawdata[i:j]) |
| 124 |
i = j |
| 125 |
if i == n: break |
| 126 |
if rawdata[i] == '<': |
| 127 |
if starttagopen.match(rawdata, i): |
| 128 |
if self.literal: |
| 129 |
self.handle_data(rawdata[i]) |
| 130 |
i = i+1 |
| 131 |
continue |
| 132 |
k = self.parse_starttag(i) |
| 133 |
if k < 0: break |
| 134 |
i = k |
| 135 |
continue |
| 136 |
if rawdata.startswith("</", i): |
| 137 |
k = self.parse_endtag(i) |
| 138 |
if k < 0: break |
| 139 |
i = k |
| 140 |
self.literal = 0 |
| 141 |
continue |
| 142 |
if self.literal: |
| 143 |
if n > (i + 1): |
| 144 |
self.handle_data("<") |
| 145 |
i = i+1 |
| 146 |
else: |
| 147 |
# incomplete |
| 148 |
break |
| 149 |
continue |
| 150 |
if rawdata.startswith("<!--", i): |
| 151 |
# Strictly speaking, a comment is --.*-- |
| 152 |
# within a declaration tag <!...>. |
| 153 |
# This should be removed, |
| 154 |
# and comments handled only in parse_declaration. |
| 155 |
k = self.parse_comment(i) |
| 156 |
if k < 0: break |
| 157 |
i = k |
| 158 |
continue |
| 159 |
if rawdata.startswith("<?", i): |
| 160 |
k = self.parse_pi(i) |
| 161 |
if k < 0: break |
| 162 |
i = i+k |
| 163 |
continue |
| 164 |
if rawdata.startswith("<!", i): |
| 165 |
# This is some sort of declaration; in "HTML as |
| 166 |
# deployed," this should only be the document type |
| 167 |
# declaration ("<!DOCTYPE html...>"). |
| 168 |
k = self.parse_declaration(i) |
| 169 |
if k < 0: break |
| 170 |
i = k |
| 171 |
continue |
| 172 |
elif rawdata[i] == '&': |
| 173 |
if self.literal: |
| 174 |
self.handle_data(rawdata[i]) |
| 175 |
i = i+1 |
| 176 |
continue |
| 177 |
match = charref.match(rawdata, i) |
| 178 |
if match: |
| 179 |
name = match.group(1) |
| 180 |
self.handle_charref(name) |
| 181 |
i = match.end(0) |
| 182 |
if rawdata[i-1] != ';': i = i-1 |
| 183 |
continue |
| 184 |
match = entityref.match(rawdata, i) |
| 185 |
if match: |
| 186 |
name = match.group(1) |
| 187 |
self.handle_entityref(name) |
| 188 |
i = match.end(0) |
| 189 |
if rawdata[i-1] != ';': i = i-1 |
| 190 |
continue |
| 191 |
else: |
| 192 |
self.error('neither < nor & ??') |
| 193 |
# We get here only if incomplete matches but |
| 194 |
# nothing else |
| 195 |
match = incomplete.match(rawdata, i) |
| 196 |
if not match: |
| 197 |
self.handle_data(rawdata[i]) |
| 198 |
i = i+1 |
| 199 |
continue |
| 200 |
j = match.end(0) |
| 201 |
if j == n: |
| 202 |
break # Really incomplete |
| 203 |
self.handle_data(rawdata[i:j]) |
| 204 |
i = j |
| 205 |
# end while |
| 206 |
if end and i < n: |
| 207 |
self.handle_data(rawdata[i:n]) |
| 208 |
i = n |
| 209 |
self.rawdata = rawdata[i:] |
| 210 |
# XXX if end: check for empty stack |
| 211 |
|
| 212 |
# Extensions for the DOCTYPE scanner: |
| 213 |
_decl_otherchars = '=' |
| 214 |
|
| 215 |
# Internal -- parse processing instr, return length or -1 if not terminated |
| 216 |
def parse_pi(self, i): |
| 217 |
rawdata = self.rawdata |
| 218 |
if rawdata[i:i+2] != '<?': |
| 219 |
self.error('unexpected call to parse_pi()') |
| 220 |
match = piclose.search(rawdata, i+2) |
| 221 |
if not match: |
| 222 |
return -1 |
| 223 |
j = match.start(0) |
| 224 |
self.handle_pi(rawdata[i+2: j]) |
| 225 |
j = match.end(0) |
| 226 |
return j-i |
| 227 |
|
| 228 |
def get_starttag_text(self): |
| 229 |
return self.__starttag_text |
| 230 |
|
| 231 |
# Internal -- handle starttag, return length or -1 if not terminated |
| 232 |
def parse_starttag(self, i): |
| 233 |
self.__starttag_text = None |
| 234 |
start_pos = i |
| 235 |
rawdata = self.rawdata |
| 236 |
if shorttagopen.match(rawdata, i): |
| 237 |
# SGML shorthand: <tag/data/ == <tag>data</tag> |
| 238 |
# XXX Can data contain &... (entity or char refs)? |
| 239 |
# XXX Can data contain < or > (tag characters)? |
| 240 |
# XXX Can there be whitespace before the first /? |
| 241 |
match = shorttag.match(rawdata, i) |
| 242 |
if not match: |
| 243 |
return -1 |
| 244 |
tag, data = match.group(1, 2) |
| 245 |
self.__starttag_text = '<%s/' % tag |
| 246 |
tag = tag.lower() |
| 247 |
k = match.end(0) |
| 248 |
self.finish_shorttag(tag, data) |
| 249 |
self.__starttag_text = rawdata[start_pos:match.end(1) + 1] |
| 250 |
return k |
| 251 |
# XXX The following should skip matching quotes (' or ") |
| 252 |
# As a shortcut way to exit, this isn't so bad, but shouldn't |
| 253 |
# be used to locate the actual end of the start tag since the |
| 254 |
# < or > characters may be embedded in an attribute value. |
| 255 |
match = endbracket.search(rawdata, i+1) |
| 256 |
if not match: |
| 257 |
return -1 |
| 258 |
j = match.start(0) |
| 259 |
# Now parse the data between i+1 and j into a tag and attrs |
| 260 |
attrs = [] |
| 261 |
if rawdata[i:i+2] == '<>': |
| 262 |
# SGML shorthand: <> == <last open tag seen> |
| 263 |
k = j |
| 264 |
tag = self.lasttag |
| 265 |
else: |
| 266 |
match = tagfind.match(rawdata, i+1) |
| 267 |
if not match: |
| 268 |
self.error('unexpected call to parse_starttag') |
| 269 |
k = match.end(0) |
| 270 |
tag = rawdata[i+1:k].lower() |
| 271 |
self.lasttag = tag |
| 272 |
while k < j: |
| 273 |
match = attrfind.match(rawdata, k) |
| 274 |
if not match: break |
| 275 |
attrname, rest, attrvalue = match.group(1, 2, 3) |
| 276 |
if not rest: |
| 277 |
attrvalue = attrname |
| 278 |
else: |
| 279 |
if (attrvalue[:1] == "'" == attrvalue[-1:] or |
| 280 |
attrvalue[:1] == '"' == attrvalue[-1:]): |
| 281 |
# strip quotes |
| 282 |
attrvalue = attrvalue[1:-1] |
| 283 |
attrvalue = self.entity_or_charref.sub( |
| 284 |
self._convert_ref, attrvalue) |
| 285 |
attrs.append((attrname.lower(), attrvalue)) |
| 286 |
k = match.end(0) |
| 287 |
if rawdata[j] == '>': |
| 288 |
j = j+1 |
| 289 |
self.__starttag_text = rawdata[start_pos:j] |
| 290 |
self.finish_starttag(tag, attrs) |
| 291 |
return j |
| 292 |
|
| 293 |
# Internal -- convert entity or character reference |
| 294 |
def _convert_ref(self, match): |
| 295 |
if match.group(2): |
| 296 |
return self.convert_charref(match.group(2)) or \ |
| 297 |
'&#%s%s' % match.groups()[1:] |
| 298 |
elif match.group(3): |
| 299 |
return self.convert_entityref(match.group(1)) or \ |
| 300 |
'&%s;' % match.group(1) |
| 301 |
else: |
| 302 |
return '&%s' % match.group(1) |
| 303 |
|
| 304 |
# Internal -- parse endtag |
| 305 |
def parse_endtag(self, i): |
| 306 |
rawdata = self.rawdata |
| 307 |
match = endbracket.search(rawdata, i+1) |
| 308 |
if not match: |
| 309 |
return -1 |
| 310 |
j = match.start(0) |
| 311 |
tag = rawdata[i+2:j].strip().lower() |
| 312 |
if rawdata[j] == '>': |
| 313 |
j = j+1 |
| 314 |
self.finish_endtag(tag) |
| 315 |
return j |
| 316 |
|
| 317 |
# Internal -- finish parsing of <tag/data/ (same as <tag>data</tag>) |
| 318 |
def finish_shorttag(self, tag, data): |
| 319 |
self.finish_starttag(tag, []) |
| 320 |
self.handle_data(data) |
| 321 |
self.finish_endtag(tag) |
| 322 |
|
| 323 |
# Internal -- finish processing of start tag |
| 324 |
# Return -1 for unknown tag, 0 for open-only tag, 1 for balanced tag |
| 325 |
def finish_starttag(self, tag, attrs): |
| 326 |
try: |
| 327 |
method = getattr(self, 'start_' + tag) |
| 328 |
except AttributeError: |
| 329 |
try: |
| 330 |
method = getattr(self, 'do_' + tag) |
| 331 |
except AttributeError: |
| 332 |
self.unknown_starttag(tag, attrs) |
| 333 |
return -1 |
| 334 |
else: |
| 335 |
self.handle_starttag(tag, method, attrs) |
| 336 |
return 0 |
| 337 |
else: |
| 338 |
self.stack.append(tag) |
| 339 |
self.handle_starttag(tag, method, attrs) |
| 340 |
return 1 |
| 341 |
|
| 342 |
# Internal -- finish processing of end tag |
| 343 |
def finish_endtag(self, tag): |
| 344 |
if not tag: |
| 345 |
found = len(self.stack) - 1 |
| 346 |
if found < 0: |
| 347 |
self.unknown_endtag(tag) |
| 348 |
return |
| 349 |
else: |
| 350 |
if tag not in self.stack: |
| 351 |
try: |
| 352 |
method = getattr(self, 'end_' + tag) |
| 353 |
except AttributeError: |
| 354 |
self.unknown_endtag(tag) |
| 355 |
else: |
| 356 |
self.report_unbalanced(tag) |
| 357 |
return |
| 358 |
found = len(self.stack) |
| 359 |
for i in range(found): |
| 360 |
if self.stack[i] == tag: found = i |
| 361 |
while len(self.stack) > found: |
| 362 |
tag = self.stack[-1] |
| 363 |
try: |
| 364 |
method = getattr(self, 'end_' + tag) |
| 365 |
except AttributeError: |
| 366 |
method = None |
| 367 |
if method: |
| 368 |
self.handle_endtag(tag, method) |
| 369 |
else: |
| 370 |
self.unknown_endtag(tag) |
| 371 |
del self.stack[-1] |
| 372 |
|
| 373 |
# Overridable -- handle start tag |
| 374 |
def handle_starttag(self, tag, method, attrs): |
| 375 |
method(attrs) |
| 376 |
|
| 377 |
# Overridable -- handle end tag |
| 378 |
def handle_endtag(self, tag, method): |
| 379 |
method() |
| 380 |
|
| 381 |
# Example -- report an unbalanced </...> tag. |
| 382 |
def report_unbalanced(self, tag): |
| 383 |
if self.verbose: |
| 384 |
print('*** Unbalanced </' + tag + '>') |
| 385 |
print('*** Stack:', self.stack) |
| 386 |
|
| 387 |
def convert_charref(self, name): |
| 388 |
"""Convert character reference, may be overridden.""" |
| 389 |
try: |
| 390 |
n = int(name) |
| 391 |
except ValueError: |
| 392 |
return |
| 393 |
if not 0 <= n <= 127: |
| 394 |
return |
| 395 |
return self.convert_codepoint(n) |
| 396 |
|
| 397 |
def convert_codepoint(self, codepoint): |
| 398 |
return chr(codepoint) |
| 399 |
|
| 400 |
def handle_charref(self, name): |
| 401 |
"""Handle character reference, no need to override.""" |
| 402 |
replacement = self.convert_charref(name) |
| 403 |
if replacement is None: |
| 404 |
self.unknown_charref(name) |
| 405 |
else: |
| 406 |
self.handle_data(replacement) |
| 407 |
|
| 408 |
# Definition of entities -- derived classes may override |
| 409 |
entitydefs = \ |
| 410 |
{'lt': '<', 'gt': '>', 'amp': '&', 'quot': '"', 'apos': '\''} |
| 411 |
|
| 412 |
def convert_entityref(self, name): |
| 413 |
"""Convert entity references. |
| 414 |
|
| 415 |
As an alternative to overriding this method; one can tailor the |
| 416 |
results by setting up the self.entitydefs mapping appropriately. |
| 417 |
""" |
| 418 |
table = self.entitydefs |
| 419 |
if name in table: |
| 420 |
return table[name] |
| 421 |
else: |
| 422 |
return |
| 423 |
|
| 424 |
def handle_entityref(self, name): |
| 425 |
"""Handle entity references, no need to override.""" |
| 426 |
replacement = self.convert_entityref(name) |
| 427 |
if replacement is None: |
| 428 |
self.unknown_entityref(name) |
| 429 |
else: |
| 430 |
self.handle_data(replacement) |
| 431 |
|
| 432 |
# Example -- handle data, should be overridden |
| 433 |
def handle_data(self, data): |
| 434 |
pass |
| 435 |
|
| 436 |
# Example -- handle comment, could be overridden |
| 437 |
def handle_comment(self, data): |
| 438 |
pass |
| 439 |
|
| 440 |
# Example -- handle declaration, could be overridden |
| 441 |
def handle_decl(self, decl): |
| 442 |
pass |
| 443 |
|
| 444 |
# Example -- handle processing instruction, could be overridden |
| 445 |
def handle_pi(self, data): |
| 446 |
pass |
| 447 |
|
| 448 |
# To be overridden -- handlers for unknown objects |
| 449 |
def unknown_starttag(self, tag, attrs): pass |
| 450 |
def unknown_endtag(self, tag): pass |
| 451 |
def unknown_charref(self, ref): pass |
| 452 |
def unknown_entityref(self, ref): pass |
| 453 |
|
| 454 |
|
| 455 |
class TestSGMLParser(SGMLParser): |
| 456 |
|
| 457 |
def __init__(self, verbose=0): |
| 458 |
self.testdata = "" |
| 459 |
SGMLParser.__init__(self, verbose) |
| 460 |
|
| 461 |
def handle_data(self, data): |
| 462 |
self.testdata = self.testdata + data |
| 463 |
if len(repr(self.testdata)) >= 70: |
| 464 |
self.flush() |
| 465 |
|
| 466 |
def flush(self): |
| 467 |
data = self.testdata |
| 468 |
if data: |
| 469 |
self.testdata = "" |
| 470 |
print('data:', repr(data)) |
| 471 |
|
| 472 |
def handle_comment(self, data): |
| 473 |
self.flush() |
| 474 |
r = repr(data) |
| 475 |
if len(r) > 68: |
| 476 |
r = r[:32] + '...' + r[-32:] |
| 477 |
print('comment:', r) |
| 478 |
|
| 479 |
def unknown_starttag(self, tag, attrs): |
| 480 |
self.flush() |
| 481 |
if not attrs: |
| 482 |
print('start tag: <' + tag + '>') |
| 483 |
else: |
| 484 |
print('start tag: <' + tag, end=' ') |
| 485 |
for name, value in attrs: |
| 486 |
print(name + '=' + '"' + value + '"', end=' ') |
| 487 |
print('>') |
| 488 |
|
| 489 |
def unknown_endtag(self, tag): |
| 490 |
self.flush() |
| 491 |
print('end tag: </' + tag + '>') |
| 492 |
|
| 493 |
def unknown_entityref(self, ref): |
| 494 |
self.flush() |
| 495 |
print('*** unknown entity ref: &' + ref + ';') |
| 496 |
|
| 497 |
def unknown_charref(self, ref): |
| 498 |
self.flush() |
| 499 |
print('*** unknown char ref: &#' + ref + ';') |
| 500 |
|
| 501 |
def unknown_decl(self, data): |
| 502 |
self.flush() |
| 503 |
print('*** unknown decl: [' + data + ']') |
| 504 |
|
| 505 |
def close(self): |
| 506 |
SGMLParser.close(self) |
| 507 |
self.flush() |
| 508 |
|
| 509 |
|
| 510 |
def test(args = None): |
| 511 |
import sys |
| 512 |
|
| 513 |
if args is None: |
| 514 |
args = sys.argv[1:] |
| 515 |
|
| 516 |
if args and args[0] == '-s': |
| 517 |
args = args[1:] |
| 518 |
klass = SGMLParser |
| 519 |
else: |
| 520 |
klass = TestSGMLParser |
| 521 |
|
| 522 |
if args: |
| 523 |
file = args[0] |
| 524 |
else: |
| 525 |
file = 'test.html' |
| 526 |
|
| 527 |
if file == '-': |
| 528 |
f = sys.stdin |
| 529 |
else: |
| 530 |
try: |
| 531 |
f = open(file, 'r') |
| 532 |
except IOError as msg: |
| 533 |
print(file, ":", msg) |
| 534 |
sys.exit(1) |
| 535 |
|
| 536 |
data = f.read() |
| 537 |
if f is not sys.stdin: |
| 538 |
f.close() |
| 539 |
|
| 540 |
x = klass() |
| 541 |
for c in data: |
| 542 |
x.feed(c) |
| 543 |
x.close() |
| 544 |
|
| 545 |
|
| 546 |
if __name__ == '__main__': |
| 547 |
test() |