from collections import OrderedDict
from typing import Dict, List, Optional, Text, Union
from os.path import dirname, join
from xml.parsers import expat
import xml.etree.ElementTree as etree # noqa: N813
_catalog = join(dirname(__file__), "catalog")
def _wrap_error(e: expat.error) -> etree.ParseError:
err = etree.ParseError(e)
err.code = e.code
err.position = e.lineno, e.offset
raise err
_names: Dict[Text, Text] = {}
def _fixname(key: Text) -> Text:
try:
name = _names[key]
except KeyError:
name = key
if "}" in name:
name = "{" + name
_names[key] = name
return name
_undefined_entity_code: int = expat.errors.codes[expat.errors.XML_ERROR_UNDEFINED_ENTITY]
class XMLParser:
"""
An XML parser with support for XHTML DTDs and all Python-supported encodings
This implements the API defined by
xml.etree.ElementTree.XMLParser, but supports XHTML DTDs
(therefore allowing XHTML entities) and supports all encodings
Python does, rather than just those supported by expat.
"""
def __init__(self, encoding: Optional[Text] = None) -> None:
self._parser = expat.ParserCreate(encoding, "}")
self._target = etree.TreeBuilder()
# parser settings
self._parser.buffer_text = True
self._parser.ordered_attributes = True
self._parser.SetParamEntityParsing(expat.XML_PARAM_ENTITY_PARSING_UNLESS_STANDALONE)
# parser callbacks
self._parser.XmlDeclHandler = self._xml_decl
self._parser.StartElementHandler = self._start
self._parser.EndElementHandler = self._end
self._parser.CharacterDataHandler = self._data
self._parser.ExternalEntityRefHandler = self._external
self._parser.SkippedEntityHandler = self._skipped
# used for our horrible re-encoding hack
self._fed_data: Optional[List[bytes]] = []
self._read_encoding: Optional[Text] = None
def _xml_decl(self, version: Text, encoding: Optional[Text], standalone: int) -> None:
self._read_encoding = encoding
def _start(self, tag: Text, attrib_in: List[str]) -> etree.Element:
assert isinstance(tag, str)
self._fed_data = None
tag = _fixname(tag)
attrib: Dict[Union[bytes, Text], Union[bytes, Text]] = OrderedDict()
if attrib_in:
for i in range(0, len(attrib_in), 2):
attrib[_fixname(attrib_in[i])] = attrib_in[i+1]
return self._target.start(tag, attrib)
def _data(self, text: Text) -> None:
self._target.data(text)
def _end(self, tag: Text) -> etree.Element:
return self._target.end(_fixname(tag))
def _external(self, context: Text, base: Optional[Text], system_id: Optional[Text], public_id: Optional[Text]) -> bool:
if public_id in {
"-//W3C//DTD XHTML 1.0 Transitional//EN",
"-//W3C//DTD XHTML 1.1//EN",
"-//W3C//DTD XHTML 1.0 Strict//EN",
"-//W3C//DTD XHTML 1.0 Frameset//EN",
"-//W3C//DTD XHTML Basic 1.0//EN",
"-//W3C//DTD XHTML 1.1 plus MathML 2.0//EN",
"-//W3C//DTD XHTML 1.1 plus MathML 2.0 plus SVG 1.1//EN",
"-//W3C//DTD MathML 2.0//EN",
"-//WAPFORUM//DTD XHTML Mobile 1.0//EN"
}:
parser = self._parser.ExternalEntityParserCreate(context)
with open(join(_catalog, "xhtml.dtd"), "rb") as fp:
try:
parser.ParseFile(fp)
except expat.error:
return False
return True
def _skipped(self, name: Text, is_parameter_entity: bool) -> None:
err = expat.error("undefined entity %s: line %d, column %d" %
(name, self._parser.ErrorLineNumber,
self._parser.ErrorColumnNumber))
err.code = _undefined_entity_code
err.lineno = self._parser.ErrorLineNumber
err.offset = self._parser.ErrorColumnNumber
raise err
def feed(self, data: bytes) -> None:
if self._fed_data is not None:
self._fed_data.append(data)
try:
self._parser.Parse(data, False)
except expat.error as v:
_wrap_error(v)
except ValueError as e:
if e.args[0] == 'multi-byte encodings are not supported':
assert self._read_encoding is not None
assert self._fed_data is not None
xml = b"".join(self._fed_data).decode(self._read_encoding).encode("utf-8")
new_parser = XMLParser("utf-8")
self._parser = new_parser._parser
self._target = new_parser._target
self._fed_data = None
self.feed(xml)
def close(self) -> etree.Element:
try:
self._parser.Parse("", True)
except expat.error as v:
_wrap_error(v)
tree = self._target.close()
return tree
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