cpython/Lib/html/parser.py at 3.4 · 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 warnings

import _markupbase

from html import unescape

__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]')

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

piclose = re.compile('>')

commentclose = re.compile(r'--\s*>')

# Note:

# 1) the strict attrfind isn't really strict, but we can't make it

# correctly strict without breaking backward compatibility;

# 2) if you change tagfind/attrfind remember to update locatestarttagend too;

# 3) if you change tagfind/attrfind and/or locatestarttagend the parser will

# explode, so don't do it.

tagfind = re.compile('([a-zA-Z][-.a-zA-Z0-9:_]*)(?:\s|/(?!>))*')

# see http://www.w3.org/TR/html5/tokenization.html#tag-open-state

# and http://www.w3.org/TR/html5/tokenization.html#tag-name-state

tagfind_tolerant = re.compile('([a-zA-Z][^\t\n\r\f />\x00]*)(?:\s|/(?!>))*')

attrfind = re.compile(

r'\s*([a-zA-Z_][-.:a-zA-Z_0-9]*)(\s*=\s*'

r'(\'[^\']*\'|"[^"]*"|[^\s"\'=<>`]*))?')

attrfind_tolerant = re.compile(

r'((?<=[\'"\s/])[^\s/>][^\s/=>]*)(\s*=+\s*'

r'(\'[^\']*\'|"[^"]*"|(?![\'"])[^>\s]*))?(?:\s|/(?!>))*')

locatestarttagend = re.compile(r"""

<[a-zA-Z][-.a-zA-Z0-9:_]* # tag name

(?:\s+ # whitespace before attribute name

(?:[a-zA-Z_][-.:a-zA-Z0-9_]* # attribute name

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

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

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

|[^'\">\s]+ # bare value

)

\s* # trailing whitespace

""", re.VERBOSE)

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 comma

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

\s* # trailing whitespace

""", re.VERBOSE)

endendtag = re.compile('>')

# the HTML 5 spec, section 8.1.2.2, doesn't allow spaces between

# </ and the tag name, so maybe this should be fixed

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

class HTMLParseError(Exception):

"""Exception raised for all parse errors."""

def __init__(self, msg, position=(None, None)):

assert msg

self.msg = msg

self.lineno = position[0]

self.offset = position[1]

def __str__(self):

result = self.msg

if self.lineno is not None:

result = result + ", at line %d" % self.lineno

if self.offset is not None:

result = result + ", column %d" % (self.offset + 1)

return result

_default_sentinel = object()

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.

"""

CDATA_CONTENT_ELEMENTS = ("script", "style")

def __init__(self, strict=_default_sentinel, *,

convert_charrefs=_default_sentinel):

"""Initialize and reset this instance.

If convert_charrefs is True (default: False), all character references

are automatically converted to the corresponding Unicode characters.

If strict is set to False (the default) the parser will parse invalid

markup, otherwise it will raise an error. Note that the strict mode

and argument are deprecated.

"""

if strict is not _default_sentinel:

warnings.warn("The strict argument and mode are deprecated.",

DeprecationWarning, stacklevel=2)

else:

strict = False # default

self.strict = strict

if convert_charrefs is _default_sentinel:

convert_charrefs = False # default

warnings.warn("The value of convert_charrefs will become True in "

"3.5. You are encouraged to set the value explicitly.",

DeprecationWarning, stacklevel=2)

self.convert_charrefs = convert_charrefs

self.reset()

def reset(self):

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

self.rawdata = ''

self.lasttag = '???'

self.interesting = interesting_normal

self.cdata_elem = None

_markupbase.ParserBase.reset(self)

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').

"""

self.rawdata = self.rawdata + data

self.goahead(0)

def close(self):

"""Handle any buffered data."""

self.goahead(1)

def error(self, message):

warnings.warn("The 'error' method is deprecated.",

DeprecationWarning, stacklevel=2)

raise HTMLParseError(message, self.getpos())

__starttag_text = None

def get_starttag_text(self):

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

return self.__starttag_text

def set_cdata_mode(self, elem):

self.cdata_elem = elem.lower()

self.interesting = re.compile(r'</\s*%s\s*>' % self.cdata_elem, re.I)

def clear_cdata_mode(self):

self.interesting = interesting_normal

self.cdata_elem = None

# 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 proceding 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'[\s;]').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 not self.cdata_elem:

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):

if self.strict:

k = self.parse_declaration(i)

else:

k = self.parse_html_declaration(i)

elif (i + 1) < n:

self.handle_data("<")

k = i + 1

else:

break

if k < 0:

if not end:

break

if self.strict:

self.error("EOF in middle of construct")

k = rawdata.find('>', i + 1)

if k < 0:

k = rawdata.find('<', i + 1)

if k < 0:

k = i + 1

else:

k += 1

if self.convert_charrefs and not self.cdata_elem:

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

else:

self.handle_data(rawdata[i:k])

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

else:

if ";" in rawdata[i:]: # bail by consuming &#

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

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

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:

# match.group() will contain at least 2 chars

if end and match.group() == rawdata[i:]:

if self.strict:

self.error("EOF in middle of entity or char ref")

else:

k = match.end()

if k <= i:

k = n

i = self.updatepos(i, i + 1)

# 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 and not self.cdata_elem:

if self.convert_charrefs and not self.cdata_elem:

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+3] == '<![':

return self.parse_marked_section(i)

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 bogus comment, return length or -1 if not terminated

# see http://www.w3.org/TR/html5/tokenization.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_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):

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 = []

if self.strict:

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

else:

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:

if self.strict:

m = attrfind.match(rawdata, k)

else:

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)

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

k = m.end()

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

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

lineno, offset = self.getpos()

if "\n" in self.__starttag_text:

lineno = lineno + self.__starttag_text.count("\n")

offset = len(self.__starttag_text) \

- self.__starttag_text.rfind("\n")

else:

offset = offset + len(self.__starttag_text)

if self.strict:

self.error("junk characters in start tag: %r"

% (rawdata[k:endpos][:20],))

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:

self.set_cdata_mode(tag)

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

if self.strict:

m = locatestarttagend.match(rawdata, i)

else:

m = locatestarttagend_tolerant.match(rawdata, i)

if m:

j = m.end()

next = rawdata[j:j+1]

if next == ">":

return j + 1

if next == "/":

if rawdata.startswith("/>", j):

return j + 2

if rawdata.startswith("/", j):

# buffer boundary

return -1

# else bogus input

if self.strict:

self.updatepos(i, j + 1)

self.error("malformed empty start tag")

if j > i:

return j

else:

return i + 1

if next == "":

# end of input

return -1

if next in ("abcdefghijklmnopqrstuvwxyz=/"

"ABCDEFGHIJKLMNOPQRSTUVWXYZ"):

# end of input in or before attribute value, or we have the

# '/' from a '/>' ending

return -1

if self.strict:

self.updatepos(i, j)

self.error("malformed start tag")

if j > i:

return j

else:

return i + 1

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

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

def parse_endtag(self, i):

rawdata = self.rawdata

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

match = endendtag.search(rawdata, i+1) # >

if not match:

return -1

gtpos = match.end()

match = endtagfind.match(rawdata, i) # </ + tag + >

if not match:

if self.cdata_elem is not None:

self.handle_data(rawdata[i:gtpos])

return gtpos

if self.strict:

self.error("bad end tag: %r" % (rawdata[i:gtpos],))

# find the name: w3.org/TR/html5/tokenization.html#tag-name-state

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

if not namematch:

# w3.org/TR/html5/tokenization.html#end-tag-open-state

if rawdata[i:i+3] == '</>':

return i+3

else:

return self.parse_bogus_comment(i)

tagname = namematch.group(1).lower()

# consume and ignore other stuff between the name and the >

# Note: this is not 100% correct, since we might have things like

# </tag attr=">">, but looking for > after tha name should cover

# most of the cases and is much simpler

gtpos = rawdata.find('>', namematch.end())

self.handle_endtag(tagname)

return gtpos+1

elem = match.group(1).lower() # script or style

if self.cdata_elem is not None:

if elem != self.cdata_elem:

self.handle_data(rawdata[i:gtpos])

return gtpos

self.handle_endtag(elem.lower())

self.clear_cdata_mode()

return gtpos

# 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):

if self.strict:

self.error("unknown declaration: %r" % (data,))

# Internal -- helper to remove special character quoting

def unescape(self, s):

warnings.warn('The unescape method is deprecated and will be removed '

'in 3.5, use html.unescape() instead.',

DeprecationWarning, stacklevel=2)

return unescape(s)

cpython/Lib/html/parser.py at 3.4 · python/cpython · GitHub

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