"""A parser for SGML, using the derived class as a static DTD."""

# Note: missing in Python3

# XXX This only supports those SGML features used by HTML.

# 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). RCDATA is
# not supported at all.

from __future__ import print_function

try:
 import _markupbase as markupbase
except:
 import markupbase

import re

__all__ = ["SGMLParser", "SGMLParseError"]

# Regular expressions used for parsing

interesting = re.compile('[&<]')
incomplete = re.compile('&([a-zA-Z][a-zA-Z0-9]*|#[0-9]*)?|'
 '<([a-zA-Z][^<>]*|'
 '/([a-zA-Z][^<>]*)?|'
 '![^<>]*)?')

entityref = re.compile('&([a-zA-Z][-.a-zA-Z0-9]*)[^a-zA-Z0-9]')
charref = re.compile('&#([0-9]+)[^0-9]')

starttagopen = re.compile('<[>a-zA-Z]')
shorttagopen = re.compile('<[a-zA-Z][-.a-zA-Z0-9]*/')
shorttag = re.compile('<([a-zA-Z][-.a-zA-Z0-9]*)/([^/]*)/')
piclose = re.compile('>')
endbracket = re.compile('[<>]')
tagfind = re.compile('[a-zA-Z][-_.a-zA-Z0-9]*')
attrfind = re.compile(
 r'\s*([a-zA-Z_][-:.a-zA-Z_0-9]*)(\s*=\s*'
 r'(\'[^\']*\'|"[^"]*"|[][\-a-zA-Z0-9./,:;+*%?!&$\(\)_#=~\'"@]*))?')


class SGMLParseError(RuntimeError):
 """Exception raised for all parse errors."""
 pass


# SGML parser base class -- find tags and call handler functions.
# Usage: p = SGMLParser(); p.feed(data); ...; p.close().
# The dtd is defined by deriving a class which defines methods
# with special names to handle tags: start_foo and end_foo to handle
# <foo> and </foo>, respectively, or do_foo to handle <foo> by itself.
# (Tags are converted to lower case for this purpose.) The data
# between tags is passed to the parser by calling self.handle_data()
# with some data as argument (the data may be split up in arbitrary
# chunks). Entity references are passed by calling
# self.handle_entityref() with the entity reference as argument.

class SGMLParser(markupbase.ParserBase):
 # Definition of entities -- derived classes may override
 entity_or_charref = re.compile('&(?:'
 '([a-zA-Z][-.a-zA-Z0-9]*)|#([0-9]+)'
 ')(;?)')

 def __init__(self, verbose=0):
 """Initialize and reset this instance."""
 self.verbose = verbose
 self.reset()

 def reset(self):
 """Reset this instance. Loses all unprocessed data."""
 self.__starttag_text = None
 self.rawdata = ''
 self.stack = []
 self.lasttag = '???'
 self.nomoretags = 0
 self.literal = 0
 markupbase.ParserBase.reset(self)

 def setnomoretags(self):
 """Enter literal mode (CDATA) till EOF.

 Intended for derived classes only.
 """
 self.nomoretags = self.literal = 1

 def setliteral(self, *args):
 """Enter literal mode (CDATA).

 Intended for derived classes only.
 """
 self.literal = 1

 def feed(self, data):
 """Feed some data to the parser.

 Call this as often as you want, with as little or as much text
 as you want (may include '\n'). (This just saves the text,
 all the processing is done by goahead().)
 """

 self.rawdata = self.rawdata + data
 self.goahead(0)

 def close(self):
 """Handle the remaining data."""
 self.goahead(1)

 def error(self, message):
 raise SGMLParseError(message)

 # 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.nomoretags:
 self.handle_data(rawdata[i:n])
 i = n
 break
 match = interesting.search(rawdata, i)
 if match:
 j = match.start()
 else:
 j = n
 if i < j:
 self.handle_data(rawdata[i:j])
 i = j
 if i == n:
 break
 if rawdata[i] == '<':
 if starttagopen.match(rawdata, i):
 if self.literal:
 self.handle_data(rawdata[i])
 i = i + 1
 continue
 k = self.parse_starttag(i)
 if k < 0:
 break
 i = k
 continue
 if rawdata.startswith("</", i):
 k = self.parse_endtag(i)
 if k < 0:
 break
 i = k
 self.literal = 0
 continue
 if self.literal:
 if n > (i + 1):
 self.handle_data("<")
 i = i + 1
 else:
 # incomplete
 break
 continue
 if rawdata.startswith("<!--", i):
 # Strictly speaking, a comment is --.*--
 # within a declaration tag <!...>.
 # This should be removed,
 # and comments handled only in parse_declaration.
 k = self.parse_comment(i)
 if k < 0:
 break
 i = k
 continue
 if rawdata.startswith("<?", i):
 k = self.parse_pi(i)
 if k < 0:
 break
 i = i + k
 continue
 if rawdata.startswith("<!", i):
 # This is some sort of declaration; in "HTML as
 # deployed," this should only be the document type
 # declaration ("<!DOCTYPE html...>").
 k = self.parse_declaration(i)
 if k < 0:
 break
 i = k
 continue
 elif rawdata[i] == '&':
 if self.literal:
 self.handle_data(rawdata[i])
 i = i + 1
 continue
 match = charref.match(rawdata, i)
 if match:
 name = match.group(1)
 self.handle_charref(name)
 i = match.end(0)
 if rawdata[i - 1] != ';':
 i = i - 1
 continue
 match = entityref.match(rawdata, i)
 if match:
 name = match.group(1)
 self.handle_entityref(name)
 i = match.end(0)
 if rawdata[i - 1] != ';':
 i = i - 1
 continue
 else:
 self.error('neither < nor & ??')
 # We get here only if incomplete matches but
 # nothing else
 match = incomplete.match(rawdata, i)
 if not match:
 self.handle_data(rawdata[i])
 i = i + 1
 continue
 j = match.end(0)
 if j == n:
 break # Really incomplete
 self.handle_data(rawdata[i:j])
 i = j
 # end while
 if end and i < n:
 self.handle_data(rawdata[i:n])
 i = n
 self.rawdata = rawdata[i:]
 # XXX if end: check for empty stack

 # Extensions for the DOCTYPE scanner:
 _decl_otherchars = '='

 # Internal -- parse processing instr, return length or -1 if not terminated
 def parse_pi(self, i):
 rawdata = self.rawdata
 if rawdata[i:i + 2] != '<?':
 self.error('unexpected call to parse_pi()')
 match = piclose.search(rawdata, i + 2)
 if not match:
 return -1
 j = match.start(0)
 self.handle_pi(rawdata[i + 2: j])
 j = match.end(0)
 return j - i

 def get_starttag_text(self):
 return self.__starttag_text

 # Internal -- handle starttag, return length or -1 if not terminated
 def parse_starttag(self, i):
 self.__starttag_text = None
 start_pos = i
 rawdata = self.rawdata
 if shorttagopen.match(rawdata, i):
 # SGML shorthand: <tag/data/ == <tag>data</tag>
 # XXX Can data contain &... (entity or char refs)?
 # XXX Can data contain < or > (tag characters)?
 # XXX Can there be whitespace before the first /?
 match = shorttag.match(rawdata, i)
 if not match:
 return -1
 tag, data = match.group(1, 2)
 self.__starttag_text = '<%s/' % tag
 tag = tag.lower()
 k = match.end(0)
 self.finish_shorttag(tag, data)
 self.__starttag_text = rawdata[start_pos:match.end(1) + 1]
 return k
 # XXX The following should skip matching quotes (' or ")
 # As a shortcut way to exit, this isn't so bad, but shouldn't
 # be used to locate the actual end of the start tag since the
 # < or > characters may be embedded in an attribute value.
 match = endbracket.search(rawdata, i + 1)
 if not match:
 return -1
 j = match.start(0)
 # Now parse the data between i + 1 and j into a tag and attrs
 attrs = []
 if rawdata[i:i + 2] == '<>':
 # SGML shorthand: <> == <last open tag seen>
 k = j
 tag = self.lasttag
 else:
 match = tagfind.match(rawdata, i + 1)
 if not match:
 self.error('unexpected call to parse_starttag')
 k = match.end(0)
 tag = rawdata[i + 1:k].lower()
 self.lasttag = tag
 while k < j:
 match = attrfind.match(rawdata, k)
 if not match:
 break
 attrname, rest, attrvalue = match.group(1, 2, 3)
 if not rest:
 attrvalue = attrname
 else:
 if (attrvalue[:1] == "'" == attrvalue[-1:] or
 attrvalue[:1] == '"' == attrvalue[-1:]):
 # strip quotes
 attrvalue = attrvalue[1:-1]
 attrvalue = self.entity_or_charref.sub(
 self._convert_ref, attrvalue)
 attrs.append((attrname.lower(), attrvalue))
 k = match.end(0)
 if rawdata[j] == '>':
 j = j + 1
 self.__starttag_text = rawdata[start_pos:j]
 self.finish_starttag(tag, attrs)
 return j

 # Internal -- convert entity or character reference
 def _convert_ref(self, match):
 if match.group(2):
 return self.convert_charref(match.group(2)) or \
 '&#%s%s' % match.groups()[1:]
 elif match.group(3):
 return self.convert_entityref(match.group(1)) or \
 '&%s;' % match.group(1)
 else:
 return '&%s' % match.group(1)

 # Internal -- parse endtag
 def parse_endtag(self, i):
 rawdata = self.rawdata
 match = endbracket.search(rawdata, i + 1)
 if not match:
 return -1
 j = match.start(0)
 tag = rawdata[i + 2:j].strip().lower()
 if rawdata[j] == '>':
 j = j + 1
 self.finish_endtag(tag)
 return j

 # Internal -- finish parsing of <tag/data/ (same as <tag>data</tag>)
 def finish_shorttag(self, tag, data):
 self.finish_starttag(tag, [])
 self.handle_data(data)
 self.finish_endtag(tag)

 # Internal -- finish processing of start tag
 # Return -1 for unknown tag, 0 for open-only tag, 1 for balanced tag
 def finish_starttag(self, tag, attrs):
 try:
 method = getattr(self, 'start_' + tag)
 except AttributeError:
 try:
 method = getattr(self, 'do_' + tag)
 except AttributeError:
 self.unknown_starttag(tag, attrs)
 return -1
 else:
 self.handle_starttag(tag, method, attrs)
 return 0
 else:
 self.stack.append(tag)
 self.handle_starttag(tag, method, attrs)
 return 1

 # Internal -- finish processing of end tag
 def finish_endtag(self, tag):
 if not tag:
 found = len(self.stack) - 1
 if found < 0:
 self.unknown_endtag(tag)
 return
 else:
 if tag not in self.stack:
 try:
 method = getattr(self, 'end_' + tag)
 except AttributeError:
 self.unknown_endtag(tag)
 else:
 self.report_unbalanced(tag)
 return
 found = len(self.stack)
 for i in range(found):
 if self.stack[i] == tag:
 found = i
 while len(self.stack) > found:
 tag = self.stack[-1]
 try:
 method = getattr(self, 'end_' + tag)
 except AttributeError:
 method = None
 if method:
 self.handle_endtag(tag, method)
 else:
 self.unknown_endtag(tag)
 del self.stack[-1]

 # Overridable -- handle start tag
 def handle_starttag(self, tag, method, attrs):
 method(attrs)

 # Overridable -- handle end tag
 def handle_endtag(self, tag, method):
 method()

 # Example -- report an unbalanced </...> tag.
 def report_unbalanced(self, tag):
 if self.verbose:
 print('*** Unbalanced </' + tag + '>')
 print('*** Stack:', self.stack)

 def convert_charref(self, name):
 """Convert character reference, may be overridden."""
 try:
 n = int(name)
 except ValueError:
 return
 if not 0 <= n <= 127:
 return
 return self.convert_codepoint(n)

 def convert_codepoint(self, codepoint):
 return chr(codepoint)

 def handle_charref(self, name):
 """Handle character reference, no need to override."""
 replacement = self.convert_charref(name)
 if replacement is None:
 self.unknown_charref(name)
 else:
 self.handle_data(replacement)

 # Definition of entities -- derived classes may override
 entitydefs = \
 {'lt': '<', 'gt': '>', 'amp': '&', 'quot': '"', 'apos': '\''}

 def convert_entityref(self, name):
 """Convert entity references.

 As an alternative to overriding this method; one can tailor the
 results by setting up the self.entitydefs mapping appropriately.
 """
 table = self.entitydefs
 if name in table:
 return table[name]
 else:
 return

 def handle_entityref(self, name):
 """Handle entity references, no need to override."""
 replacement = self.convert_entityref(name)
 if replacement is None:
 self.unknown_entityref(name)
 else:
 self.handle_data(replacement)

 # Example -- handle data, should be overridden
 def handle_data(self, data):
 pass

 # Example -- handle comment, could be overridden
 def handle_comment(self, data):
 pass

 # Example -- handle declaration, could be overridden
 def handle_decl(self, decl):
 pass

 # Example -- handle processing instruction, could be overridden
 def handle_pi(self, data):
 pass

 # To be overridden -- handlers for unknown objects
 def unknown_starttag(self, tag, attrs):
 pass

 def unknown_endtag(self, tag):
 pass

 def unknown_charref(self, ref):
 pass

 def unknown_entityref(self, ref):
 pass


class TestSGMLParser(SGMLParser):

 def __init__(self, verbose=0):
 self.testdata = ""
 SGMLParser.__init__(self, verbose)

 def handle_data(self, data):
 self.testdata = self.testdata + data
 if len(repr(self.testdata)) >= 70:
 self.flush()

 def flush(self):
 data = self.testdata
 if data:
 self.testdata = ""
 print('data:', repr(data))

 def handle_comment(self, data):
 self.flush()
 r = repr(data)
 if len(r) > 68:
 r = r[:32] + '...' + r[-32:]
 print('comment:', r)

 def unknown_starttag(self, tag, attrs):
 self.flush()
 if not attrs:
 print('start tag: <' + tag + '>')
 else:
 print('start tag: <' + tag, end=' ')
 for name, value in attrs:
 print(name + '=' + '"' + value + '"', end=' ')
 print('>')

 def unknown_endtag(self, tag):
 self.flush()
 print('end tag: </' + tag + '>')

 def unknown_entityref(self, ref):
 self.flush()
 print('*** unknown entity ref: &' + ref + ';')

 def unknown_charref(self, ref):
 self.flush()
 print('*** unknown char ref: &#' + ref + ';')

 def unknown_decl(self, data):
 self.flush()
 print('*** unknown decl: [' + data + ']')

 def close(self):
 SGMLParser.close(self)
 self.flush()


def test(args=None):
 import sys

 if args is None:
 args = sys.argv[1:]

 if args and args[0] == '-s':
 args = args[1:]
 klass = SGMLParser
 else:
 klass = TestSGMLParser

 if args:
 file = args[0]
 else:
 file = 'test.html'

 if file == '-':
 f = sys.stdin
 else:
 try:
 f = open(file, 'r')
 except IOError as msg:
 print(file, ":", msg)
 sys.exit(1)

 data = f.read()
 if f is not sys.stdin:
 f.close()

 x = klass()
 for c in data:
 x.feed(c)
 x.close()


if __name__ == '__main__':
 test()