cpython/Lib/html/parser.py at 3.15 · python/cpython · GitHub

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"""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 3.15 · python/cpython · GitHub

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parser.py

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