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1"""Shared support for scanning document type declarations in HTML and XHTML.
2
3This module is used as a foundation for the HTMLParser and sgmllib
4modules (indirectly, for htmllib as well).  It has no documented
5public API and should not be used directly.
6
7"""
8
9import re
10
11_declname_match = re.compile(r'[a-zA-Z][-_.a-zA-Z0-9]*\s*').match
12_declstringlit_match = re.compile(r'(\'[^\']*\'|"[^"]*")\s*').match
13_commentclose = re.compile(r'--\s*>')
14_markedsectionclose = re.compile(r']\s*]\s*>')
15
16# An analysis of the MS-Word extensions is available at
17# http://www.planetpublish.com/xmlarena/xap/Thursday/WordtoXML.pdf
18
19_msmarkedsectionclose = re.compile(r']\s*>')
20
21del re
22
23
24class ParserBase:
25    """Parser base class which provides some common support methods used
26    by the SGML/HTML and XHTML parsers."""
27
28    def __init__(self):
29        if self.__class__ is ParserBase:
30            raise RuntimeError(
31                "markupbase.ParserBase must be subclassed")
32
33    def error(self, message):
34        raise NotImplementedError(
35            "subclasses of ParserBase must override error()")
36
37    def reset(self):
38        self.lineno = 1
39        self.offset = 0
40
41    def getpos(self):
42        """Return current line number and offset."""
43        return self.lineno, self.offset
44
45    # Internal -- update line number and offset.  This should be
46    # called for each piece of data exactly once, in order -- in other
47    # words the concatenation of all the input strings to this
48    # function should be exactly the entire input.
49    def updatepos(self, i, j):
50        if i >= j:
51            return j
52        rawdata = self.rawdata
53        nlines = rawdata.count("\n", i, j)
54        if nlines:
55            self.lineno = self.lineno + nlines
56            pos = rawdata.rindex("\n", i, j) # Should not fail
57            self.offset = j-(pos+1)
58        else:
59            self.offset = self.offset + j-i
60        return j
61
62    _decl_otherchars = ''
63
64    # Internal -- parse declaration (for use by subclasses).
65    def parse_declaration(self, i):
66        # This is some sort of declaration; in "HTML as
67        # deployed," this should only be the document type
68        # declaration ("<!DOCTYPE html...>").
69        # ISO 8879:1986, however, has more complex
70        # declaration syntax for elements in <!...>, including:
71        # --comment--
72        # [marked section]
73        # name in the following list: ENTITY, DOCTYPE, ELEMENT,
74        # ATTLIST, NOTATION, SHORTREF, USEMAP,
75        # LINKTYPE, LINK, IDLINK, USELINK, SYSTEM
76        rawdata = self.rawdata
77        j = i + 2
78        assert rawdata[i:j] == "<!", "unexpected call to parse_declaration"
79        if rawdata[j:j+1] == ">":
80            # the empty comment <!>
81            return j + 1
82        if rawdata[j:j+1] in ("-", ""):
83            # Start of comment followed by buffer boundary,
84            # or just a buffer boundary.
85            return -1
86        # A simple, practical version could look like: ((name|stringlit) S*) + '>'
87        n = len(rawdata)
88        if rawdata[j:j+2] == '--': #comment
89            # Locate --.*-- as the body of the comment
90            return self.parse_comment(i)
91        elif rawdata[j] == '[': #marked section
92            # Locate [statusWord [...arbitrary SGML...]] as the body of the marked section
93            # Where statusWord is one of TEMP, CDATA, IGNORE, INCLUDE, RCDATA
94            # Note that this is extended by Microsoft Office "Save as Web" function
95            # to include [if...] and [endif].
96            return self.parse_marked_section(i)
97        else: #all other declaration elements
98            decltype, j = self._scan_name(j, i)
99        if j < 0:
100            return j
101        if decltype == "doctype":
102            self._decl_otherchars = ''
103        while j < n:
104            c = rawdata[j]
105            if c == ">":
106                # end of declaration syntax
107                data = rawdata[i+2:j]
108                if decltype == "doctype":
109                    self.handle_decl(data)
110                else:
111                    self.unknown_decl(data)
112                return j + 1
113            if c in "\"'":
114                m = _declstringlit_match(rawdata, j)
115                if not m:
116                    return -1 # incomplete
117                j = m.end()
118            elif c in "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ":
119                name, j = self._scan_name(j, i)
120            elif c in self._decl_otherchars:
121                j = j + 1
122            elif c == "[":
123                # this could be handled in a separate doctype parser
124                if decltype == "doctype":
125                    j = self._parse_doctype_subset(j + 1, i)
126                elif decltype in ("attlist", "linktype", "link", "element"):
127                    # must tolerate []'d groups in a content model in an element declaration
128                    # also in data attribute specifications of attlist declaration
129                    # also link type declaration subsets in linktype declarations
130                    # also link attribute specification lists in link declarations
131                    self.error("unsupported '[' char in %s declaration" % decltype)
132                else:
133                    self.error("unexpected '[' char in declaration")
134            else:
135                self.error(
136                    "unexpected %r char in declaration" % rawdata[j])
137            if j < 0:
138                return j
139        return -1 # incomplete
140
141    # Internal -- parse a marked section
142    # Override this to handle MS-word extension syntax <![if word]>content<![endif]>
143    def parse_marked_section(self, i, report=1):
144        rawdata= self.rawdata
145        assert rawdata[i:i+3] == '<![', "unexpected call to parse_marked_section()"
146        sectName, j = self._scan_name( i+3, i )
147        if j < 0:
148            return j
149        if sectName in ("temp", "cdata", "ignore", "include", "rcdata"):
150            # look for standard ]]> ending
151            match= _markedsectionclose.search(rawdata, i+3)
152        elif sectName in ("if", "else", "endif"):
153            # look for MS Office ]> ending
154            match= _msmarkedsectionclose.search(rawdata, i+3)
155        else:
156            self.error('unknown status keyword %r in marked section' % rawdata[i+3:j])
157        if not match:
158            return -1
159        if report:
160            j = match.start(0)
161            self.unknown_decl(rawdata[i+3: j])
162        return match.end(0)
163
164    # Internal -- parse comment, return length or -1 if not terminated
165    def parse_comment(self, i, report=1):
166        rawdata = self.rawdata
167        if rawdata[i:i+4] != '<!--':
168            self.error('unexpected call to parse_comment()')
169        match = _commentclose.search(rawdata, i+4)
170        if not match:
171            return -1
172        if report:
173            j = match.start(0)
174            self.handle_comment(rawdata[i+4: j])
175        return match.end(0)
176
177    # Internal -- scan past the internal subset in a <!DOCTYPE declaration,
178    # returning the index just past any whitespace following the trailing ']'.
179    def _parse_doctype_subset(self, i, declstartpos):
180        rawdata = self.rawdata
181        n = len(rawdata)
182        j = i
183        while j < n:
184            c = rawdata[j]
185            if c == "<":
186                s = rawdata[j:j+2]
187                if s == "<":
188                    # end of buffer; incomplete
189                    return -1
190                if s != "<!":
191                    self.updatepos(declstartpos, j + 1)
192                    self.error("unexpected char in internal subset (in %r)" % s)
193                if (j + 2) == n:
194                    # end of buffer; incomplete
195                    return -1
196                if (j + 4) > n:
197                    # end of buffer; incomplete
198                    return -1
199                if rawdata[j:j+4] == "<!--":
200                    j = self.parse_comment(j, report=0)
201                    if j < 0:
202                        return j
203                    continue
204                name, j = self._scan_name(j + 2, declstartpos)
205                if j == -1:
206                    return -1
207                if name not in ("attlist", "element", "entity", "notation"):
208                    self.updatepos(declstartpos, j + 2)
209                    self.error(
210                        "unknown declaration %r in internal subset" % name)
211                # handle the individual names
212                meth = getattr(self, "_parse_doctype_" + name)
213                j = meth(j, declstartpos)
214                if j < 0:
215                    return j
216            elif c == "%":
217                # parameter entity reference
218                if (j + 1) == n:
219                    # end of buffer; incomplete
220                    return -1
221                s, j = self._scan_name(j + 1, declstartpos)
222                if j < 0:
223                    return j
224                if rawdata[j] == ";":
225                    j = j + 1
226            elif c == "]":
227                j = j + 1
228                while j < n and rawdata[j].isspace():
229                    j = j + 1
230                if j < n:
231                    if rawdata[j] == ">":
232                        return j
233                    self.updatepos(declstartpos, j)
234                    self.error("unexpected char after internal subset")
235                else:
236                    return -1
237            elif c.isspace():
238                j = j + 1
239            else:
240                self.updatepos(declstartpos, j)
241                self.error("unexpected char %r in internal subset" % c)
242        # end of buffer reached
243        return -1
244
245    # Internal -- scan past <!ELEMENT declarations
246    def _parse_doctype_element(self, i, declstartpos):
247        name, j = self._scan_name(i, declstartpos)
248        if j == -1:
249            return -1
250        # style content model; just skip until '>'
251        rawdata = self.rawdata
252        if '>' in rawdata[j:]:
253            return rawdata.find(">", j) + 1
254        return -1
255
256    # Internal -- scan past <!ATTLIST declarations
257    def _parse_doctype_attlist(self, i, declstartpos):
258        rawdata = self.rawdata
259        name, j = self._scan_name(i, declstartpos)
260        c = rawdata[j:j+1]
261        if c == "":
262            return -1
263        if c == ">":
264            return j + 1
265        while 1:
266            # scan a series of attribute descriptions; simplified:
267            #   name type [value] [#constraint]
268            name, j = self._scan_name(j, declstartpos)
269            if j < 0:
270                return j
271            c = rawdata[j:j+1]
272            if c == "":
273                return -1
274            if c == "(":
275                # an enumerated type; look for ')'
276                if ")" in rawdata[j:]:
277                    j = rawdata.find(")", j) + 1
278                else:
279                    return -1
280                while rawdata[j:j+1].isspace():
281                    j = j + 1
282                if not rawdata[j:]:
283                    # end of buffer, incomplete
284                    return -1
285            else:
286                name, j = self._scan_name(j, declstartpos)
287            c = rawdata[j:j+1]
288            if not c:
289                return -1
290            if c in "'\"":
291                m = _declstringlit_match(rawdata, j)
292                if m:
293                    j = m.end()
294                else:
295                    return -1
296                c = rawdata[j:j+1]
297                if not c:
298                    return -1
299            if c == "#":
300                if rawdata[j:] == "#":
301                    # end of buffer
302                    return -1
303                name, j = self._scan_name(j + 1, declstartpos)
304                if j < 0:
305                    return j
306                c = rawdata[j:j+1]
307                if not c:
308                    return -1
309            if c == '>':
310                # all done
311                return j + 1
312
313    # Internal -- scan past <!NOTATION declarations
314    def _parse_doctype_notation(self, i, declstartpos):
315        name, j = self._scan_name(i, declstartpos)
316        if j < 0:
317            return j
318        rawdata = self.rawdata
319        while 1:
320            c = rawdata[j:j+1]
321            if not c:
322                # end of buffer; incomplete
323                return -1
324            if c == '>':
325                return j + 1
326            if c in "'\"":
327                m = _declstringlit_match(rawdata, j)
328                if not m:
329                    return -1
330                j = m.end()
331            else:
332                name, j = self._scan_name(j, declstartpos)
333                if j < 0:
334                    return j
335
336    # Internal -- scan past <!ENTITY declarations
337    def _parse_doctype_entity(self, i, declstartpos):
338        rawdata = self.rawdata
339        if rawdata[i:i+1] == "%":
340            j = i + 1
341            while 1:
342                c = rawdata[j:j+1]
343                if not c:
344                    return -1
345                if c.isspace():
346                    j = j + 1
347                else:
348                    break
349        else:
350            j = i
351        name, j = self._scan_name(j, declstartpos)
352        if j < 0:
353            return j
354        while 1:
355            c = self.rawdata[j:j+1]
356            if not c:
357                return -1
358            if c in "'\"":
359                m = _declstringlit_match(rawdata, j)
360                if m:
361                    j = m.end()
362                else:
363                    return -1    # incomplete
364            elif c == ">":
365                return j + 1
366            else:
367                name, j = self._scan_name(j, declstartpos)
368                if j < 0:
369                    return j
370
371    # Internal -- scan a name token and the new position and the token, or
372    # return -1 if we've reached the end of the buffer.
373    def _scan_name(self, i, declstartpos):
374        rawdata = self.rawdata
375        n = len(rawdata)
376        if i == n:
377            return None, -1
378        m = _declname_match(rawdata, i)
379        if m:
380            s = m.group()
381            name = s.strip()
382            if (i + len(s)) == n:
383                return None, -1  # end of buffer
384            return name.lower(), m.end()
385        else:
386            self.updatepos(declstartpos, i)
387            self.error("expected name token at %r"
388                       % rawdata[declstartpos:declstartpos+20])
389
390    # To be overridden -- handlers for unknown objects
391    def unknown_decl(self, data):
392        pass
393