cpython/Lib/html/parser.py at main · python/cpython · GitHub

History

583 lines (530 loc) · 22.5 KB

Raw

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

115

116

117

118

119

120

121

122

123

124

125

126

127

128

129

130

131

132

133

134

135

136

137

138

139

140

141

142

143

144

145

146

147

148

149

150

151

152

153

154

155

156

157

158

159

160

161

162

163

164

165

166

167

168

169

170

171

172

173

174

175

176

177

178

179

180

181

182

183

184

185

186

187

188

189

190

191

192

193

194

195

196

197

198

199

200

201

202

203

204

205

206

207

208

209

210

211

212

213

214

215

216

217

218

219

220

221

222

223

224

225

226

227

228

229

230

231

232

233

234

235

236

237

238

239

240

241

242

243

244

245

246

247

248

249

250

251

252

253

254

255

256

257

258

259

260

261

262

263

264

265

266

267

268

269

270

271

272

273

274

275

276

277

278

279

280

281

282

283

284

285

286

287

288

289

290

291

292

293

294

295

296

297

298

299

300

301

302

303

304

305

306

307

308

309

310

311

312

313

314

315

316

317

318

319

320

321

322

323

324

325

326

327

328

329

330

331

332

333

334

335

336

337

338

339

340

341

342

343

344

345

346

347

348

349

350

351

352

353

354

355

356

357

358

359

360

361

362

363

364

365

366

367

368

369

370

371

372

373

374

375

376

377

378

379

380

381

382

383

384

385

386

387

388

389

390

391

392

393

394

395

396

397

398

399

400

401

402

403

404

405

406

407

408

409

410

411

412

413

414

415

416

417

418

419

420

421

422

423

424

425

426

427

428

429

430

431

432

433

434

435

436

437

438

439

440

441

442

443

444

445

446

447

448

449

450

451

452

453

454

455

456

457

458

459

460

461

462

463

464

465

466

467

468

469

470

471

472

473

474

475

476

477

478

479

480

481

482

483

484

485

486

487

488

489

490

491

492

493

494

495

496

497

498

499

500

501

502

503

504

505

506

507

508

509

510

511

512

513

514

515

516

517

518

519

520

521

522

523

524

525

526

527

528

529

530

531

532

533

534

535

536

537

538

539

540

541

542

543

544

545

546

547

548

549

550

551

552

553

554

555

556

557

558

559

560

561

562

563

564

565

566

567

568

569

570

571

572

573

574

575

576

577

578

579

580

581

582

583

"""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 re

import _markupbase

from html import unescape

from html.entities import html5 as html5_entities

__all__ = ['HTMLParser']

# Regular expressions used for parsing

interesting_normal = re.compile('[&<]')

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]')

incomplete_charref = re.compile('&#(?:[0-9]|[xX][0-9a-fA-F])')

attr_charref = re.compile(r'&(#[0-9]+|#[xX][0-9a-fA-F]+|[a-zA-Z][a-zA-Z0-9]*)[;=]?')

starttagopen = re.compile('<[a-zA-Z]')

endtagopen = re.compile('</[a-zA-Z]')

piclose = re.compile('>')

commentclose = re.compile(r'--!?>')

commentabruptclose = re.compile(r'-?>')

# Note:

# 1) if you change tagfind/attrfind remember to update locatetagend too;

# 2) if you change tagfind/attrfind and/or locatetagend the parser will

# explode, so don't do it.

# see the HTML5 specs section "13.2.5.6 Tag open state",

# "13.2.5.8 Tag name state" and "13.2.5.33 Attribute name state".

# https://html.spec.whatwg.org/multipage/parsing.html#tag-open-state

# https://html.spec.whatwg.org/multipage/parsing.html#tag-name-state

# https://html.spec.whatwg.org/multipage/parsing.html#attribute-name-state

tagfind_tolerant = re.compile(r'([a-zA-Z][^\t\n\r\f />]*)(?:[\t\n\r\f ]|/(?!>))*')

attrfind_tolerant = re.compile(r"""

(

(?<=['"\t\n\r\f /])[^\t\n\r\f />][^\t\n\r\f /=>]* # attribute name

)

([\t\n\r\f ]*=[\t\n\r\f ]* # value indicator

('[^']*' # LITA-enclosed value

|"[^"]*" # LIT-enclosed value

|(?!['"])[^>\t\n\r\f ]* # bare value

)

(?:[\t\n\r\f ]|/(?!>))* # possibly followed by a space

""", re.VERBOSE)

locatetagend = re.compile(r"""

[a-zA-Z][^\t\n\r\f />]* # tag name

[\t\n\r\f /]* # optional whitespace before attribute name

(?:(?<=['"\t\n\r\f /])[^\t\n\r\f />][^\t\n\r\f /=>]* # attribute name

(?:[\t\n\r\f ]*=[\t\n\r\f ]* # value indicator

(?:'[^']*' # LITA-enclosed value

|"[^"]*" # LIT-enclosed value

|(?!['"])[^>\t\n\r\f ]* # bare value

)

[\t\n\r\f /]* # possibly followed by a space

""", re.VERBOSE)

# The following variables are not used, but are temporarily left for

# backward compatibility.

locatestarttagend_tolerant = re.compile(r"""

<[a-zA-Z][^\t\n\r\f />\x00]* # tag name

(?:[\s/]* # optional whitespace before attribute name

(?:(?<=['"\s/])[^\s/>][^\s/=>]* # attribute name

(?:\s*=+\s* # value indicator

(?:'[^']*' # LITA-enclosed value

|"[^"]*" # LIT-enclosed value

|(?!['"])[^>\s]* # bare value

)

\s* # possibly followed by a space

)?(?:\s|/(?!>))*

\s* # trailing whitespace

""", re.VERBOSE)

endendtag = re.compile('>')

endtagfind = re.compile(r'</\s*([a-zA-Z][-.a-zA-Z0-9:_]*)\s*>')

# Character reference processing logic specific to attribute values

# See: https://html.spec.whatwg.org/multipage/parsing.html#named-character-reference-state

def _replace_attr_charref(match):

ref = match.group(0)

# Numeric / hex char refs must always be unescaped

if ref.startswith('&#'):

return unescape(ref)

# Named character / entity references must only be unescaped

# if they are an exact match, and they are not followed by an equals sign

if not ref.endswith('=') and ref[1:] in html5_entities:

return unescape(ref)

# Otherwise do not unescape

return ref

def _unescape_attrvalue(s):

return attr_charref.sub(_replace_attr_charref, s)

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). If convert_charrefs is

True the character references are converted automatically to the

corresponding Unicode character (and self.handle_data() is no

longer split in chunks), otherwise they are passed by calling

self.handle_entityref() or self.handle_charref() with the string

containing respectively the named or numeric reference as the

argument.

"""

# See the HTML5 specs section "13.4 Parsing HTML fragments".

# https://html.spec.whatwg.org/multipage/parsing.html#parsing-html-fragments

# CDATA_CONTENT_ELEMENTS are parsed in RAWTEXT mode

CDATA_CONTENT_ELEMENTS = ("script", "style", "xmp", "iframe", "noembed", "noframes")

RCDATA_CONTENT_ELEMENTS = ("textarea", "title")

def __init__(self, *, convert_charrefs=True, scripting=False):

"""Initialize and reset this instance.

If convert_charrefs is true (the default), all character references

are automatically converted to the corresponding Unicode characters.

If *scripting* is false (the default), the content of the

``noscript`` element is parsed normally; if it's true,

it's returned as is without being parsed.

"""

super().__init__()

self.convert_charrefs = convert_charrefs

self.scripting = scripting

self.reset()

def reset(self):

"""Reset this instance. Loses all unprocessed data."""

self.rawdata = ''

self.lasttag = '???'

self.interesting = interesting_normal

self.cdata_elem = None

self._support_cdata = True

self._escapable = True

self._pending = []

self._pending_len = 0

self._parse_threshold = 1

super().reset()

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').

"""

# Accumulate new data in a list and only join and parse it once

# enough has piled up. Rescanning an unparsed buffer (e.g. an

# unterminated tag) and concatenating onto it on every call would

# both be quadratic in the input size.

self._pending_len += len(data)

if self._pending_len < self._parse_threshold:

self._pending.append(data)

else:

if not self._pending:

self.rawdata += data

else:

self._pending.append(data)

self.rawdata += ''.join(self._pending)

self._pending.clear()

self._pending_len = 0

n = len(self.rawdata)

self.goahead(0)

if len(self.rawdata) < n:

# Some data was parsed; resume on the next call.

self._parse_threshold = 1

else:

# Nothing was parsed; wait until the buffer doubles.

self._parse_threshold = len(self.rawdata)

def close(self):

"""Handle any buffered data."""

if self._pending:

self.rawdata += ''.join(self._pending)

self._pending.clear()

self._pending_len = 0

self.goahead(1)

__starttag_text = None

def get_starttag_text(self):

"""Return full source of start tag: '<...>'."""

return self.__starttag_text

def set_cdata_mode(self, elem, *, escapable=False):

self.cdata_elem = elem.lower()

self._escapable = escapable

if self.cdata_elem == 'plaintext':

self.interesting = re.compile(r'\z')

elif escapable and not self.convert_charrefs:

self.interesting = re.compile(r'&|</%s(?=[\t\n\r\f />])' % self.cdata_elem,

re.IGNORECASE|re.ASCII)

else:

self.interesting = re.compile(r'</%s(?=[\t\n\r\f />])' % self.cdata_elem,

re.IGNORECASE|re.ASCII)

def clear_cdata_mode(self):

self.interesting = interesting_normal

self.cdata_elem = None

self._escapable = True

def _set_support_cdata(self, flag=True):

"""Enable or disable support of the CDATA sections.

If enabled, "<[CDATA[" starts a CDATA section which ends with "]]>".

If disabled, "<[CDATA[" starts a bogus comments which ends with ">".

This method is not called by default. Its purpose is to be called

in custom handle_starttag() and handle_endtag() methods, with

value that depends on the adjusted current node.

See https://html.spec.whatwg.org/multipage/parsing.html#markup-declaration-open-state

for details.

"""

self._support_cdata = flag

# 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.convert_charrefs and not self.cdata_elem:

j = rawdata.find('<', i)

if j < 0:

# if we can't find the next <, either we are at the end

# or there's more text incoming. If the latter is True,

# we can't pass the text to handle_data in case we have

# a charref cut in half at end. Try to determine if

# this is the case before proceeding by looking for an

# & near the end and see if it's followed by a space or ;.

amppos = rawdata.rfind('&', max(i, n-34))

if (amppos >= 0 and

not re.compile(r'[\t\n\r\f ;]').search(rawdata, amppos)):

break # wait till we get all the text

j = n

else:

match = self.interesting.search(rawdata, i) # < or &

if match:

j = match.start()

else:

if self.cdata_elem:

break

j = n

if i < j:

if self.convert_charrefs and self._escapable:

self.handle_data(unescape(rawdata[i:j]))

else:

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_html_declaration(i)

elif (i + 1) < n or end:

self.handle_data("<")

k = i + 1

else:

break

if k < 0:

if not end:

break

if starttagopen.match(rawdata, i): # < + letter

pass

elif startswith("</", i):

if i + 2 == n:

self.handle_data("</")

elif endtagopen.match(rawdata, i): # </ + letter

pass

else:

# bogus comment

self.handle_comment(rawdata[i+2:])

elif startswith("<!--", i):

j = n

for suffix in ("--!", "--", "-"):

if rawdata.endswith(suffix, i+4):

j -= len(suffix)

break

self.handle_comment(rawdata[i+4:j])

elif startswith("<![CDATA[", i) and self._support_cdata:

self.unknown_decl(rawdata[i+3:])

elif rawdata[i:i+9].lower() == '<!doctype':

self.handle_decl(rawdata[i+2:])

elif startswith("<!", i):

# bogus comment

self.handle_comment(rawdata[i+2:])

elif startswith("<?", i):

self.handle_pi(rawdata[i+2:])

else:

raise AssertionError("we should not get here!")

k = n

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

match = incomplete_charref.match(rawdata, i)

if match:

if end:

self.handle_charref(rawdata[i+2:])

i = self.updatepos(i, n)

break

# incomplete

break

elif i + 3 < n: # larger than "&#x"

# not the end of the buffer, and can't be confused

# with some other construct

self.handle_data("&#")

i = self.updatepos(i, i + 2)

else:

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:

if end:

self.handle_entityref(rawdata[i+1:])

i = self.updatepos(i, n)

break

# 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:

if self.convert_charrefs and self._escapable:

self.handle_data(unescape(rawdata[i:n]))

else:

self.handle_data(rawdata[i:n])

i = self.updatepos(i, n)

self.rawdata = rawdata[i:]

# Internal -- parse html declarations, return length or -1 if not terminated

# See w3.org/TR/html5/tokenization.html#markup-declaration-open-state

# See also parse_declaration in _markupbase

def parse_html_declaration(self, i):

rawdata = self.rawdata

assert rawdata[i:i+2] == '<!', ('unexpected call to '

'parse_html_declaration()')

if rawdata[i:i+4] == '<!--':

# this case is actually already handled in goahead()

return self.parse_comment(i)

elif rawdata[i:i+9] == '<![CDATA[' and self._support_cdata:

j = rawdata.find(']]>', i+9)

if j < 0:

return -1

self.unknown_decl(rawdata[i+3: j])

return j + 3

elif rawdata[i:i+9].lower() == '<!doctype':

# find the closing >

gtpos = rawdata.find('>', i+9)

if gtpos == -1:

return -1

self.handle_decl(rawdata[i+2:gtpos])

return gtpos+1

else:

return self.parse_bogus_comment(i)

# Internal -- parse comment, return length or -1 if not terminated

# see https://html.spec.whatwg.org/multipage/parsing.html#comment-start-state

def parse_comment(self, i, report=True):

rawdata = self.rawdata

assert rawdata.startswith('<!--', i), 'unexpected call to parse_comment()'

# An empty comment is abruptly closed by the first ">" or "->",

# taking priority over a later "-->" or "--!>" close.

match = commentabruptclose.match(rawdata, i+4)

if not match:

match = commentclose.search(rawdata, i+4)

if not match:

return -1

if report:

j = match.start()

self.handle_comment(rawdata[i+4: j])

return match.end()

# Internal -- parse bogus comment, return length or -1 if not terminated

# see https://html.spec.whatwg.org/multipage/parsing.html#bogus-comment-state

def parse_bogus_comment(self, i, report=1):

rawdata = self.rawdata

assert rawdata[i:i+2] in ('<!', '</'), ('unexpected call to '

'parse_bogus_comment()')

pos = rawdata.find('>', i+2)

if pos == -1:

return -1

if report:

self.handle_comment(rawdata[i+2:pos])

return pos + 1

# 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):

# See the HTML5 specs section "13.2.5.8 Tag name state"

# https://html.spec.whatwg.org/multipage/parsing.html#tag-name-state

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_tolerant.match(rawdata, i+1)

assert match, 'unexpected call to parse_starttag()'

k = match.end()

self.lasttag = tag = match.group(1).lower()

while k < endpos:

m = attrfind_tolerant.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]

if attrvalue:

attrvalue = _unescape_attrvalue(attrvalue)

attrs.append((attrname.lower(), attrvalue))

k = m.end()

end = rawdata[k:endpos].strip()

if end not in (">", "/>"):

self.handle_data(rawdata[i:endpos])

return endpos

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 or

(self.scripting and tag == "noscript") or

tag == "plaintext"):

self.set_cdata_mode(tag, escapable=False)

elif tag in self.RCDATA_CONTENT_ELEMENTS:

self.set_cdata_mode(tag, escapable=True)

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

match = locatetagend.match(rawdata, i+1)

assert match

j = match.end()

if rawdata[j-1] != ">":

return -1

return j

# Internal -- parse endtag, return end or -1 if incomplete

def parse_endtag(self, i):

# See the HTML5 specs section "13.2.5.7 End tag open state"

# https://html.spec.whatwg.org/multipage/parsing.html#end-tag-open-state

rawdata = self.rawdata

assert rawdata[i:i+2] == "</", "unexpected call to parse_endtag"

if rawdata.find('>', i+2) < 0: # fast check

return -1

if not endtagopen.match(rawdata, i): # </ + letter

if rawdata[i+2:i+3] == '>': # </> is ignored

# "missing-end-tag-name" parser error

return i+3

else:

return self.parse_bogus_comment(i)

match = locatetagend.match(rawdata, i+2)

assert match

j = match.end()

if rawdata[j-1] != ">":

return -1

# find the name: "13.2.5.8 Tag name state"

# https://html.spec.whatwg.org/multipage/parsing.html#tag-name-state

match = tagfind_tolerant.match(rawdata, i+2)

assert match

tag = match.group(1).lower()

self.handle_endtag(tag)

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):

pass

cpython/Lib/html/parser.py at main · python/cpython · GitHub

Uh oh!

Uh oh!

cpython/Lib/html/parser.py at main · python/cpython · GitHub

Uh oh!

Uh oh!

Expand file tree

Breadcrumbs

parser.py

Latest commit

History

Breadcrumbs

parser.py

File metadata and controls