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

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

# explode, so don't do it.

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

attrfind_tolerant = re.compile(

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

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

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

"""

CDATA_CONTENT_ELEMENTS = ("script", "style")

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

"""Initialize and reset this instance.

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

are automatically converted to the corresponding Unicode characters.

"""

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)

__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 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'[\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):

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

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:]:

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 = []

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)

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)

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

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 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 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

# 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)

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):

pass

# 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)