Forgot to commit sgmllib3.py

src/searchengine/nova3/sgmllib3.py

@@ -0,0 +1,547 @@
+"""A parser for SGML, using the derived class as a static DTD."""
+
+# 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.
+
+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()