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	"""Shared support for scanning document type declarations in HTML and XHTML.

	This module is used as a foundation for the html.parser module. It has no
	documented public API and should not be used directly.

	"""

	import re

	_declname_match = re.compile(r'[a-zA-Z][-_.a-zA-Z0-9]\s').match
	_declstringlit_match = re.compile(r'(\'[^\']\'\|"[^"]")\s*').match
	_commentclose = re.compile(r'--\s*>')
	_markedsectionclose = re.compile(r']\s]\s>')

	# An analysis of the MS-Word extensions is available at
	# http://www.planetpublish.com/xmlarena/xap/Thursday/WordtoXML.pdf

	_msmarkedsectionclose = re.compile(r']\s*>')

	del re


	class ParserBase:
	"""Parser base class which provides some common support methods used
	by the SGML/HTML and XHTML parsers."""

	def __init__(self):
	if self.__class__ is ParserBase:
	raise RuntimeError(
	"_markupbase.ParserBase must be subclassed")

	def reset(self):
	self.lineno = 1
	self.offset = 0

	def getpos(self):
	"""Return current line number and offset."""
	return self.lineno, self.offset

	# Internal -- update line number and offset. This should be
	# called for each piece of data exactly once, in order -- in other
	# words the concatenation of all the input strings to this
	# function should be exactly the entire input.
	def updatepos(self, i, j):
	if i >= j:
	return j
	rawdata = self.rawdata
	nlines = rawdata.count("\n", i, j)
	if nlines:
	self.lineno = self.lineno + nlines
	pos = rawdata.rindex("\n", i, j) # Should not fail
	self.offset = j-(pos+1)
	else:
	self.offset = self.offset + j-i
	return j

	_decl_otherchars = ''

	# Internal -- parse declaration (for use by subclasses).
	def parse_declaration(self, i):
	# This is some sort of declaration; in "HTML as
	# deployed," this should only be the document type
	# declaration ("<!DOCTYPE html...>").
	# ISO 8879:1986, however, has more complex
	# declaration syntax for elements in <!...>, including:
	# --comment--
	# [marked section]
	# name in the following list: ENTITY, DOCTYPE, ELEMENT,
	# ATTLIST, NOTATION, SHORTREF, USEMAP,
	# LINKTYPE, LINK, IDLINK, USELINK, SYSTEM
	rawdata = self.rawdata
	j = i + 2
	assert rawdata[i:j] == "<!", "unexpected call to parse_declaration"
	if rawdata[j:j+1] == ">":
	# the empty comment <!>
	return j + 1
	if rawdata[j:j+1] in ("-", ""):
	# Start of comment followed by buffer boundary,
	# or just a buffer boundary.
	return -1
	# A simple, practical version could look like: ((name\|stringlit) S*) + '>'
	n = len(rawdata)
	if rawdata[j:j+2] == '--': #comment
	# Locate --.*-- as the body of the comment
	return self.parse_comment(i)
	elif rawdata[j] == '[': #marked section
	# Locate [statusWord [...arbitrary SGML...]] as the body of the marked section
	# Where statusWord is one of TEMP, CDATA, IGNORE, INCLUDE, RCDATA
	# Note that this is extended by Microsoft Office "Save as Web" function
	# to include [if...] and [endif].
	return self.parse_marked_section(i)
	else: #all other declaration elements
	decltype, j = self._scan_name(j, i)
	if j < 0:
	return j
	if decltype == "doctype":
	self._decl_otherchars = ''
	while j < n:
	c = rawdata[j]
	if c == ">":
	# end of declaration syntax
	data = rawdata[i+2:j]
	if decltype == "doctype":
	self.handle_decl(data)
	else:
	# According to the HTML5 specs sections "8.2.4.44 Bogus
	# comment state" and "8.2.4.45 Markup declaration open
	# state", a comment token should be emitted.
	# Calling unknown_decl provides more flexibility though.
	self.unknown_decl(data)
	return j + 1
	if c in "\"'":
	m = _declstringlit_match(rawdata, j)
	if not m:
	return -1 # incomplete
	j = m.end()
	elif c in "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ":
	name, j = self._scan_name(j, i)
	elif c in self._decl_otherchars:
	j = j + 1
	elif c == "[":
	# this could be handled in a separate doctype parser
	if decltype == "doctype":
	j = self._parse_doctype_subset(j + 1, i)
	elif decltype in {"attlist", "linktype", "link", "element"}:
	# must tolerate []'d groups in a content model in an element declaration
	# also in data attribute specifications of attlist declaration
	# also link type declaration subsets in linktype declarations
	# also link attribute specification lists in link declarations
	raise AssertionError("unsupported '[' char in %s declaration" % decltype)
	else:
	raise AssertionError("unexpected '[' char in declaration")
	else:
	raise AssertionError("unexpected %r char in declaration" % rawdata[j])
	if j < 0:
	return j
	return -1 # incomplete

	# Internal -- parse a marked section
	# Override this to handle MS-word extension syntax <![if word]>content<![endif]>
	def parse_marked_section(self, i, report=1):
	rawdata= self.rawdata
	assert rawdata[i:i+3] == '<![', "unexpected call to parse_marked_section()"
	sectName, j = self._scan_name( i+3, i )
	if j < 0:
	return j
	if sectName in {"temp", "cdata", "ignore", "include", "rcdata"}:
	# look for standard ]]> ending
	match= _markedsectionclose.search(rawdata, i+3)
	elif sectName in {"if", "else", "endif"}:
	# look for MS Office ]> ending
	match= _msmarkedsectionclose.search(rawdata, i+3)
	else:
	raise AssertionError(
	'unknown status keyword %r in marked section' % rawdata[i+3:j]
	)
	if not match:
	return -1
	if report:
	j = match.start(0)
	self.unknown_decl(rawdata[i+3: j])
	return match.end(0)

	# Internal -- parse comment, return length or -1 if not terminated
	def parse_comment(self, i, report=1):
	rawdata = self.rawdata
	if rawdata[i:i+4] != '<!--':
	raise AssertionError('unexpected call to parse_comment()')
	match = _commentclose.search(rawdata, i+4)
	if not match:
	return -1
	if report:
	j = match.start(0)
	self.handle_comment(rawdata[i+4: j])
	return match.end(0)

	# Internal -- scan past the internal subset in a <!DOCTYPE declaration,
	# returning the index just past any whitespace following the trailing ']'.
	def _parse_doctype_subset(self, i, declstartpos):
	rawdata = self.rawdata
	n = len(rawdata)
	j = i
	while j < n:
	c = rawdata[j]
	if c == "<":
	s = rawdata[j:j+2]
	if s == "<":
	# end of buffer; incomplete
	return -1
	if s != "<!":
	self.updatepos(declstartpos, j + 1)
	raise AssertionError(
	"unexpected char in internal subset (in %r)" % s
	)
	if (j + 2) == n:
	# end of buffer; incomplete
	return -1
	if (j + 4) > n:
	# end of buffer; incomplete
	return -1
	if rawdata[j:j+4] == "<!--":
	j = self.parse_comment(j, report=0)
	if j < 0:
	return j
	continue
	name, j = self._scan_name(j + 2, declstartpos)
	if j == -1:
	return -1
	if name not in {"attlist", "element", "entity", "notation"}:
	self.updatepos(declstartpos, j + 2)
	raise AssertionError(
	"unknown declaration %r in internal subset" % name
	)
	# handle the individual names
	meth = getattr(self, "_parse_doctype_" + name)
	j = meth(j, declstartpos)
	if j < 0:
	return j
	elif c == "%":
	# parameter entity reference
	if (j + 1) == n:
	# end of buffer; incomplete
	return -1
	s, j = self._scan_name(j + 1, declstartpos)
	if j < 0:
	return j
	if rawdata[j] == ";":
	j = j + 1
	elif c == "]":
	j = j + 1
	while j < n and rawdata[j].isspace():
	j = j + 1
	if j < n:
	if rawdata[j] == ">":
	return j
	self.updatepos(declstartpos, j)
	raise AssertionError("unexpected char after internal subset")
	else:
	return -1
	elif c.isspace():
	j = j + 1
	else:
	self.updatepos(declstartpos, j)
	raise AssertionError("unexpected char %r in internal subset" % c)
	# end of buffer reached
	return -1

	# Internal -- scan past <!ELEMENT declarations
	def _parse_doctype_element(self, i, declstartpos):
	name, j = self._scan_name(i, declstartpos)
	if j == -1:
	return -1
	# style content model; just skip until '>'
	rawdata = self.rawdata
	if '>' in rawdata[j:]:
	return rawdata.find(">", j) + 1
	return -1

	# Internal -- scan past <!ATTLIST declarations
	def _parse_doctype_attlist(self, i, declstartpos):
	rawdata = self.rawdata
	name, j = self._scan_name(i, declstartpos)
	c = rawdata[j:j+1]
	if c == "":
	return -1
	if c == ">":
	return j + 1
	while 1:
	# scan a series of attribute descriptions; simplified:
	# name type [value] [#constraint]
	name, j = self._scan_name(j, declstartpos)
	if j < 0:
	return j
	c = rawdata[j:j+1]
	if c == "":
	return -1
	if c == "(":
	# an enumerated type; look for ')'
	if ")" in rawdata[j:]:
	j = rawdata.find(")", j) + 1
	else:
	return -1
	while rawdata[j:j+1].isspace():
	j = j + 1
	if not rawdata[j:]:
	# end of buffer, incomplete
	return -1
	else:
	name, j = self._scan_name(j, declstartpos)
	c = rawdata[j:j+1]
	if not c:
	return -1
	if c in "'\"":
	m = _declstringlit_match(rawdata, j)
	if m:
	j = m.end()
	else:
	return -1
	c = rawdata[j:j+1]
	if not c:
	return -1
	if c == "#":
	if rawdata[j:] == "#":
	# end of buffer
	return -1
	name, j = self._scan_name(j + 1, declstartpos)
	if j < 0:
	return j
	c = rawdata[j:j+1]
	if not c:
	return -1
	if c == '>':
	# all done
	return j + 1

	# Internal -- scan past <!NOTATION declarations
	def _parse_doctype_notation(self, i, declstartpos):
	name, j = self._scan_name(i, declstartpos)
	if j < 0:
	return j
	rawdata = self.rawdata
	while 1:
	c = rawdata[j:j+1]
	if not c:
	# end of buffer; incomplete
	return -1
	if c == '>':
	return j + 1
	if c in "'\"":
	m = _declstringlit_match(rawdata, j)
	if not m:
	return -1
	j = m.end()
	else:
	name, j = self._scan_name(j, declstartpos)
	if j < 0:
	return j

	# Internal -- scan past <!ENTITY declarations
	def _parse_doctype_entity(self, i, declstartpos):
	rawdata = self.rawdata
	if rawdata[i:i+1] == "%":
	j = i + 1
	while 1:
	c = rawdata[j:j+1]
	if not c:
	return -1
	if c.isspace():
	j = j + 1
	else:
	break
	else:
	j = i
	name, j = self._scan_name(j, declstartpos)
	if j < 0:
	return j
	while 1:
	c = self.rawdata[j:j+1]
	if not c:
	return -1
	if c in "'\"":
	m = _declstringlit_match(rawdata, j)
	if m:
	j = m.end()
	else:
	return -1 # incomplete
	elif c == ">":
	return j + 1
	else:
	name, j = self._scan_name(j, declstartpos)
	if j < 0:
	return j

	# Internal -- scan a name token and the new position and the token, or
	# return -1 if we've reached the end of the buffer.
	def _scan_name(self, i, declstartpos):
	rawdata = self.rawdata
	n = len(rawdata)
	if i == n:
	return None, -1
	m = _declname_match(rawdata, i)
	if m:
	s = m.group()
	name = s.strip()
	if (i + len(s)) == n:
	return None, -1 # end of buffer
	return name.lower(), m.end()
	else:
	self.updatepos(declstartpos, i)
	raise AssertionError(
	"expected name token at %r" % rawdata[declstartpos:declstartpos+20]
	)

	# To be overridden -- handlers for unknown objects
	def unknown_decl(self, data):
	pass