week06

env/lib/python3.12/site-packages/lxml/xslt.pxi

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+# XSLT
+from lxml.includes cimport xslt
+
+
+cdef class XSLTError(LxmlError):
+    """Base class of all XSLT errors.
+    """
+
+cdef class XSLTParseError(XSLTError):
+    """Error parsing a stylesheet document.
+    """
+
+cdef class XSLTApplyError(XSLTError):
+    """Error running an XSL transformation.
+    """
+
+class XSLTSaveError(XSLTError, SerialisationError):
+    """Error serialising an XSLT result.
+    """
+
+cdef class XSLTExtensionError(XSLTError):
+    """Error registering an XSLT extension.
+    """
+
+
+# version information
+LIBXSLT_COMPILED_VERSION = __unpackIntVersion(xslt.LIBXSLT_VERSION)
+LIBXSLT_VERSION = __unpackIntVersion(xslt.xsltLibxsltVersion)
+
+
+################################################################################
+# Where do we store what?
+#
+# xsltStylesheet->doc->_private
+#    == _XSLTResolverContext for XSL stylesheet
+#
+# xsltTransformContext->_private
+#    == _XSLTResolverContext for transformed document
+#
+################################################################################
+
+
+################################################################################
+# XSLT document loaders
+
+@cython.final
+@cython.internal
+cdef class _XSLTResolverContext(_ResolverContext):
+    cdef xmlDoc* _c_style_doc
+    cdef _BaseParser _parser
+
+    cdef _XSLTResolverContext _copy(self):
+        cdef _XSLTResolverContext context
+        context = _XSLTResolverContext()
+        _initXSLTResolverContext(context, self._parser)
+        context._c_style_doc = self._c_style_doc
+        return context
+
+cdef _initXSLTResolverContext(_XSLTResolverContext context,
+                              _BaseParser parser):
+    _initResolverContext(context, parser.resolvers)
+    context._parser = parser
+    context._c_style_doc = NULL
+
+cdef xmlDoc* _xslt_resolve_from_python(const_xmlChar* c_uri, void* c_context,
+                                       int parse_options, int* error) with gil:
+    # call the Python document loaders
+    cdef _XSLTResolverContext context
+    cdef _ResolverRegistry resolvers
+    cdef _InputDocument doc_ref
+    cdef xmlDoc* c_doc
+    cdef xmlDoc* c_return_doc = NULL
+
+    error[0] = 0
+    context = <_XSLTResolverContext>c_context
+
+    # shortcut if we resolve the stylesheet itself
+    c_doc = context._c_style_doc
+    try:
+        if c_doc is not NULL and c_doc.URL is not NULL:
+            if tree.xmlStrcmp(c_uri, c_doc.URL) == 0:
+                c_return_doc = _copyDoc(c_doc, 1)
+                return c_return_doc  # 'goto', see 'finally' below
+
+        # delegate to the Python resolvers
+        resolvers = context._resolvers
+        if tree.xmlStrncmp(<unsigned char*>'string://__STRING__XSLT__/', c_uri, 26) == 0:
+            c_uri += 26
+        uri = _decodeFilename(c_uri)
+        doc_ref = resolvers.resolve(uri, None, context)
+
+        if doc_ref is not None:
+            if doc_ref._type == PARSER_DATA_STRING:
+                c_return_doc = _parseDoc(
+                    doc_ref._data_bytes, doc_ref._filename, context._parser)
+            elif doc_ref._type == PARSER_DATA_FILENAME:
+                c_return_doc = _parseDocFromFile(
+                    doc_ref._filename, context._parser)
+            elif doc_ref._type == PARSER_DATA_FILE:
+                c_return_doc = _parseDocFromFilelike(
+                    doc_ref._file, doc_ref._filename, context._parser)
+            elif doc_ref._type == PARSER_DATA_EMPTY:
+                c_return_doc = _newXMLDoc()
+            if c_return_doc is not NULL and c_return_doc.URL is NULL:
+                c_return_doc.URL = tree.xmlStrdup(c_uri)
+    except:
+        error[0] = 1
+        context._store_raised()
+    finally:
+        return c_return_doc  # and swallow any further exceptions
+
+
+cdef void _xslt_store_resolver_exception(const_xmlChar* c_uri, void* context,
+                                         xslt.xsltLoadType c_type) noexcept with gil:
+    try:
+        message = f"Cannot resolve URI {_decodeFilename(c_uri)}"
+        if c_type == xslt.XSLT_LOAD_DOCUMENT:
+            exception = XSLTApplyError(message)
+        else:
+            exception = XSLTParseError(message)
+        (<_XSLTResolverContext>context)._store_exception(exception)
+    except BaseException as e:
+        (<_XSLTResolverContext>context)._store_exception(e)
+    finally:
+        return  # and swallow any further exceptions
+
+
+cdef xmlDoc* _xslt_doc_loader(const_xmlChar* c_uri, tree.xmlDict* c_dict,
+                              int parse_options, void* c_ctxt,
+                              xslt.xsltLoadType c_type) noexcept nogil:
+    # nogil => no Python objects here, may be called without thread context !
+    cdef xmlDoc* c_doc
+    cdef xmlDoc* result
+    cdef void* c_pcontext
+    cdef int error = 0
+    # find resolver contexts of stylesheet and transformed doc
+    if c_type == xslt.XSLT_LOAD_DOCUMENT:
+        # transformation time
+        c_pcontext = (<xslt.xsltTransformContext*>c_ctxt)._private
+    elif c_type == xslt.XSLT_LOAD_STYLESHEET:
+        # include/import resolution while parsing
+        c_pcontext = (<xslt.xsltStylesheet*>c_ctxt).doc._private
+    else:
+        c_pcontext = NULL
+
+    if c_pcontext is NULL:
+        # can't call Python without context, fall back to default loader
+        return XSLT_DOC_DEFAULT_LOADER(
+            c_uri, c_dict, parse_options, c_ctxt, c_type)
+
+    c_doc = _xslt_resolve_from_python(c_uri, c_pcontext, parse_options, &error)
+    if c_doc is NULL and not error:
+        c_doc = XSLT_DOC_DEFAULT_LOADER(
+            c_uri, c_dict, parse_options, c_ctxt, c_type)
+        if c_doc is NULL:
+            _xslt_store_resolver_exception(c_uri, c_pcontext, c_type)
+
+    if c_doc is not NULL and c_type == xslt.XSLT_LOAD_STYLESHEET:
+        c_doc._private = c_pcontext
+    return c_doc
+
+cdef xslt.xsltDocLoaderFunc XSLT_DOC_DEFAULT_LOADER = xslt.xsltDocDefaultLoader
+xslt.xsltSetLoaderFunc(<xslt.xsltDocLoaderFunc>_xslt_doc_loader)
+
+################################################################################
+# XSLT file/network access control
+
+cdef class XSLTAccessControl:
+    """XSLTAccessControl(self, read_file=True, write_file=True, create_dir=True, read_network=True, write_network=True)
+
+    Access control for XSLT: reading/writing files, directories and
+    network I/O.  Access to a type of resource is granted or denied by
+    passing any of the following boolean keyword arguments.  All of
+    them default to True to allow access.
+
+    - read_file
+    - write_file
+    - create_dir
+    - read_network
+    - write_network
+
+    For convenience, there is also a class member `DENY_ALL` that
+    provides an XSLTAccessControl instance that is readily configured
+    to deny everything, and a `DENY_WRITE` member that denies all
+    write access but allows read access.
+
+    See `XSLT`.
+    """
+    cdef xslt.xsltSecurityPrefs* _prefs
+    def __cinit__(self):
+        self._prefs = xslt.xsltNewSecurityPrefs()
+        if self._prefs is NULL:
+            raise MemoryError()
+
+    def __init__(self, *, bint read_file=True, bint write_file=True, bint create_dir=True,
+                 bint read_network=True, bint write_network=True):
+        self._setAccess(xslt.XSLT_SECPREF_READ_FILE, read_file)
+        self._setAccess(xslt.XSLT_SECPREF_WRITE_FILE, write_file)
+        self._setAccess(xslt.XSLT_SECPREF_CREATE_DIRECTORY, create_dir)
+        self._setAccess(xslt.XSLT_SECPREF_READ_NETWORK, read_network)
+        self._setAccess(xslt.XSLT_SECPREF_WRITE_NETWORK, write_network)
+
+    DENY_ALL = XSLTAccessControl(
+        read_file=False, write_file=False, create_dir=False,
+        read_network=False, write_network=False)
+
+    DENY_WRITE = XSLTAccessControl(
+        read_file=True, write_file=False, create_dir=False,
+        read_network=True, write_network=False)
+
+    def __dealloc__(self):
+        if self._prefs is not NULL:
+            xslt.xsltFreeSecurityPrefs(self._prefs)
+
+    @cython.final
+    cdef _setAccess(self, xslt.xsltSecurityOption option, bint allow):
+        cdef xslt.xsltSecurityCheck function
+        if allow:
+            function = xslt.xsltSecurityAllow
+        else:
+            function = xslt.xsltSecurityForbid
+        xslt.xsltSetSecurityPrefs(self._prefs, option, function)
+
+    @cython.final
+    cdef void _register_in_context(self, xslt.xsltTransformContext* ctxt) noexcept:
+        xslt.xsltSetCtxtSecurityPrefs(self._prefs, ctxt)
+
+    @property
+    def options(self):
+        """The access control configuration as a map of options."""
+        return {
+            'read_file': self._optval(xslt.XSLT_SECPREF_READ_FILE),
+            'write_file': self._optval(xslt.XSLT_SECPREF_WRITE_FILE),
+            'create_dir': self._optval(xslt.XSLT_SECPREF_CREATE_DIRECTORY),
+            'read_network': self._optval(xslt.XSLT_SECPREF_READ_NETWORK),
+            'write_network': self._optval(xslt.XSLT_SECPREF_WRITE_NETWORK),
+        }
+
+    @cython.final
+    cdef _optval(self, xslt.xsltSecurityOption option):
+        cdef xslt.xsltSecurityCheck function
+        function = xslt.xsltGetSecurityPrefs(self._prefs, option)
+        if function is <xslt.xsltSecurityCheck>xslt.xsltSecurityAllow:
+            return True
+        elif function is <xslt.xsltSecurityCheck>xslt.xsltSecurityForbid:
+            return False
+        else:
+            return None
+
+    def __repr__(self):
+        items = sorted(self.options.items())
+        return "%s(%s)" % (
+            python._fqtypename(self).decode('UTF-8').split('.')[-1],
+            ', '.join(["%s=%r" % item for item in items]))
+
+################################################################################
+# XSLT
+
+cdef int _register_xslt_function(void* ctxt, name_utf, ns_utf) noexcept:
+    if ns_utf is None:
+        return 0
+    # libxml2 internalises the strings if ctxt has a dict
+    return xslt.xsltRegisterExtFunction(
+        <xslt.xsltTransformContext*>ctxt, _xcstr(name_utf), _xcstr(ns_utf),
+        <xslt.xmlXPathFunction>_xpath_function_call)
+
+cdef dict EMPTY_DICT = {}
+
+@cython.final
+@cython.internal
+cdef class _XSLTContext(_BaseContext):
+    cdef xslt.xsltTransformContext* _xsltCtxt
+    cdef _ReadOnlyElementProxy _extension_element_proxy
+    cdef dict _extension_elements
+    def __cinit__(self):
+        self._xsltCtxt = NULL
+        self._extension_elements = EMPTY_DICT
+
+    def __init__(self, namespaces, extensions, error_log, enable_regexp,
+                 build_smart_strings):
+        if extensions is not None and extensions:
+            for ns_name_tuple, extension in extensions.items():
+                if ns_name_tuple[0] is None:
+                    raise XSLTExtensionError, \
+                        "extensions must not have empty namespaces"
+                if isinstance(extension, XSLTExtension):
+                    if self._extension_elements is EMPTY_DICT:
+                        self._extension_elements = {}
+                        extensions = extensions.copy()
+                    ns_utf   = _utf8(ns_name_tuple[0])
+                    name_utf = _utf8(ns_name_tuple[1])
+                    self._extension_elements[(ns_utf, name_utf)] = extension
+                    del extensions[ns_name_tuple]
+        _BaseContext.__init__(self, namespaces, extensions, error_log, enable_regexp,
+                              build_smart_strings)
+
+    cdef _BaseContext _copy(self):
+        cdef _XSLTContext context
+        context = <_XSLTContext>_BaseContext._copy(self)
+        context._extension_elements = self._extension_elements
+        return context
+
+    cdef register_context(self, xslt.xsltTransformContext* xsltCtxt,
+                               _Document doc):
+        self._xsltCtxt = xsltCtxt
+        self._set_xpath_context(xsltCtxt.xpathCtxt)
+        self._register_context(doc)
+        self.registerLocalFunctions(xsltCtxt, _register_xslt_function)
+        self.registerGlobalFunctions(xsltCtxt, _register_xslt_function)
+        _registerXSLTExtensions(xsltCtxt, self._extension_elements)
+
+    cdef free_context(self):
+        self._cleanup_context()
+        self._release_context()
+        if self._xsltCtxt is not NULL:
+            xslt.xsltFreeTransformContext(self._xsltCtxt)
+            self._xsltCtxt = NULL
+        self._release_temp_refs()
+
+
+@cython.final
+@cython.internal
+@cython.freelist(8)
+cdef class _XSLTQuotedStringParam:
+    """A wrapper class for literal XSLT string parameters that require
+    quote escaping.
+    """
+    cdef bytes strval
+    def __cinit__(self, strval):
+        self.strval = _utf8(strval)
+
+
+@cython.no_gc_clear
+cdef class XSLT:
+    """XSLT(self, xslt_input, extensions=None, regexp=True, access_control=None)
+
+    Turn an XSL document into an XSLT object.
+
+    Calling this object on a tree or Element will execute the XSLT::
+
+        transform = etree.XSLT(xsl_tree)
+        result = transform(xml_tree)
+
+    Keyword arguments of the constructor:
+
+    - extensions: a dict mapping ``(namespace, name)`` pairs to
+      extension functions or extension elements
+    - regexp: enable exslt regular expression support in XPath
+      (default: True)
+    - access_control: access restrictions for network or file
+      system (see `XSLTAccessControl`)
+
+    Keyword arguments of the XSLT call:
+
+    - profile_run: enable XSLT profiling and make the profile available
+      as XML document in ``result.xslt_profile`` (default: False)
+
+    Other keyword arguments of the call are passed to the stylesheet
+    as parameters.
+    """
+    cdef _XSLTContext _context
+    cdef xslt.xsltStylesheet* _c_style
+    cdef _XSLTResolverContext _xslt_resolver_context
+    cdef XSLTAccessControl _access_control
+    cdef _ErrorLog _error_log
+
+    def __cinit__(self):
+        self._c_style = NULL
+
+    def __init__(self, xslt_input, *, extensions=None, regexp=True,
+                 access_control=None):
+        cdef xslt.xsltStylesheet* c_style = NULL
+        cdef xmlDoc* c_doc
+        cdef _Document doc
+        cdef _Element root_node
+
+        doc = _documentOrRaise(xslt_input)
+        root_node = _rootNodeOrRaise(xslt_input)
+
+        # set access control or raise TypeError
+        self._access_control = access_control
+
+        # make a copy of the document as stylesheet parsing modifies it
+        c_doc = _copyDocRoot(doc._c_doc, root_node._c_node)
+
+        # make sure we always have a stylesheet URL
+        if c_doc.URL is NULL:
+            doc_url_utf = python.PyUnicode_AsASCIIString(
+                f"string://__STRING__XSLT__/{id(self)}.xslt")
+            c_doc.URL = tree.xmlStrdup(_xcstr(doc_url_utf))
+
+        self._error_log = _ErrorLog()
+        self._xslt_resolver_context = _XSLTResolverContext()
+        _initXSLTResolverContext(self._xslt_resolver_context, doc._parser)
+        # keep a copy in case we need to access the stylesheet via 'document()'
+        self._xslt_resolver_context._c_style_doc = _copyDoc(c_doc, 1)
+        c_doc._private = <python.PyObject*>self._xslt_resolver_context
+
+        with self._error_log:
+            orig_loader = _register_document_loader()
+            c_style = xslt.xsltParseStylesheetDoc(c_doc)
+            _reset_document_loader(orig_loader)
+
+        if c_style is NULL or c_style.errors:
+            tree.xmlFreeDoc(c_doc)
+            if c_style is not NULL:
+                xslt.xsltFreeStylesheet(c_style)
+            self._xslt_resolver_context._raise_if_stored()
+            # last error seems to be the most accurate here
+            if self._error_log.last_error is not None and \
+                    self._error_log.last_error.message:
+                raise XSLTParseError(self._error_log.last_error.message,
+                                     self._error_log)
+            else:
+                raise XSLTParseError(
+                    self._error_log._buildExceptionMessage(
+                        "Cannot parse stylesheet"),
+                    self._error_log)
+
+        c_doc._private = NULL # no longer used!
+        self._c_style = c_style
+        self._context = _XSLTContext(None, extensions, self._error_log, regexp, True)
+
+    def __dealloc__(self):
+        if self._xslt_resolver_context is not None and \
+               self._xslt_resolver_context._c_style_doc is not NULL:
+            tree.xmlFreeDoc(self._xslt_resolver_context._c_style_doc)
+        # this cleans up the doc copy as well
+        if self._c_style is not NULL:
+            xslt.xsltFreeStylesheet(self._c_style)
+
+    @property
+    def error_log(self):
+        """The log of errors and warnings of an XSLT execution."""
+        return self._error_log.copy()
+
+    @staticmethod
+    def strparam(strval):
+        """strparam(strval)
+
+        Mark an XSLT string parameter that requires quote escaping
+        before passing it into the transformation.  Use it like this::
+
+            result = transform(doc, some_strval = XSLT.strparam(
+                '''it's \"Monty Python's\" ...'''))
+
+        Escaped string parameters can be reused without restriction.
+        """
+        return _XSLTQuotedStringParam(strval)
+
+    @staticmethod
+    def set_global_max_depth(int max_depth):
+        """set_global_max_depth(max_depth)
+
+        The maximum traversal depth that the stylesheet engine will allow.
+        This does not only count the template recursion depth but also takes
+        the number of variables/parameters into account.  The required setting
+        for a run depends on both the stylesheet and the input data.
+
+        Example::
+
+            XSLT.set_global_max_depth(5000)
+
+        Note that this is currently a global, module-wide setting because
+        libxslt does not support it at a per-stylesheet level.
+        """
+        if max_depth < 0:
+            raise ValueError("cannot set a maximum stylesheet traversal depth < 0")
+        xslt.xsltMaxDepth = max_depth
+
+    def tostring(self, _ElementTree result_tree):
+        """tostring(self, result_tree)
+
+        Save result doc to string based on stylesheet output method.
+
+        :deprecated: use str(result_tree) instead.
+        """
+        return str(result_tree)
+
+    def __deepcopy__(self, memo):
+        return self.__copy__()
+
+    def __copy__(self):
+        return _copyXSLT(self)
+
+    def __call__(self, _input, *, profile_run=False, **kw):
+        """__call__(self, _input, profile_run=False, **kw)
+
+        Execute the XSL transformation on a tree or Element.
+
+        Pass the ``profile_run`` option to get profile information
+        about the XSLT.  The result of the XSLT will have a property
+        xslt_profile that holds an XML tree with profiling data.
+        """
+        cdef _XSLTContext context = None
+        cdef _XSLTResolverContext resolver_context
+        cdef _Document input_doc
+        cdef _Element root_node
+        cdef _Document result_doc
+        cdef _Document profile_doc = None
+        cdef xmlDoc* c_profile_doc
+        cdef xslt.xsltTransformContext* transform_ctxt
+        cdef xmlDoc* c_result = NULL
+        cdef xmlDoc* c_doc
+        cdef tree.xmlDict* c_dict
+        cdef const_char** params = NULL
+
+        assert self._c_style is not NULL, "XSLT stylesheet not initialised"
+        input_doc = _documentOrRaise(_input)
+        root_node = _rootNodeOrRaise(_input)
+
+        c_doc = _fakeRootDoc(input_doc._c_doc, root_node._c_node)
+
+        transform_ctxt = xslt.xsltNewTransformContext(self._c_style, c_doc)
+        if transform_ctxt is NULL:
+            _destroyFakeDoc(input_doc._c_doc, c_doc)
+            raise MemoryError()
+
+        # using the stylesheet dict is safer than using a possibly
+        # unrelated dict from the current thread.  Almost all
+        # non-input tag/attr names will come from the stylesheet
+        # anyway.
+        if transform_ctxt.dict is not NULL:
+            xmlparser.xmlDictFree(transform_ctxt.dict)
+        if kw:
+            # parameter values are stored in the dict
+            # => avoid unnecessarily cluttering the global dict
+            transform_ctxt.dict = xmlparser.xmlDictCreateSub(self._c_style.doc.dict)
+            if transform_ctxt.dict is NULL:
+                xslt.xsltFreeTransformContext(transform_ctxt)
+                raise MemoryError()
+        else:
+            transform_ctxt.dict = self._c_style.doc.dict
+            xmlparser.xmlDictReference(transform_ctxt.dict)
+
+        xslt.xsltSetCtxtParseOptions(
+            transform_ctxt, input_doc._parser._parse_options)
+
+        if profile_run:
+            transform_ctxt.profile = 1
+
+        try:
+            context = self._context._copy()
+            context.register_context(transform_ctxt, input_doc)
+
+            resolver_context = self._xslt_resolver_context._copy()
+            transform_ctxt._private = <python.PyObject*>resolver_context
+
+            _convert_xslt_parameters(transform_ctxt, kw, &params)
+            c_result = self._run_transform(
+                c_doc, params, context, transform_ctxt)
+            if params is not NULL:
+                # deallocate space for parameters
+                python.lxml_free(params)
+
+            if transform_ctxt.state != xslt.XSLT_STATE_OK:
+                if c_result is not NULL:
+                    tree.xmlFreeDoc(c_result)
+                    c_result = NULL
+
+            if transform_ctxt.profile:
+                c_profile_doc = xslt.xsltGetProfileInformation(transform_ctxt)
+                if c_profile_doc is not NULL:
+                    profile_doc = _documentFactory(
+                        c_profile_doc, input_doc._parser)
+        finally:
+            if context is not None:
+                context.free_context()
+            _destroyFakeDoc(input_doc._c_doc, c_doc)
+
+        try:
+            if resolver_context is not None and resolver_context._has_raised():
+                if c_result is not NULL:
+                    tree.xmlFreeDoc(c_result)
+                    c_result = NULL
+                resolver_context._raise_if_stored()
+
+            if context._exc._has_raised():
+                if c_result is not NULL:
+                    tree.xmlFreeDoc(c_result)
+                    c_result = NULL
+                context._exc._raise_if_stored()
+
+            if c_result is NULL:
+                # last error seems to be the most accurate here
+                error = self._error_log.last_error
+                if error is not None and error.message:
+                    if error.line > 0:
+                        message = f"{error.message}, line {error.line}"
+                    else:
+                        message = error.message
+                elif error is not None and error.line > 0:
+                    message = f"Error applying stylesheet, line {error.line}"
+                else:
+                    message = "Error applying stylesheet"
+                raise XSLTApplyError(message, self._error_log)
+        finally:
+            if resolver_context is not None:
+                resolver_context.clear()
+
+        result_doc = _documentFactory(c_result, input_doc._parser)
+
+        c_dict = c_result.dict
+        xmlparser.xmlDictReference(c_dict)
+        __GLOBAL_PARSER_CONTEXT.initThreadDictRef(&c_result.dict)
+        if c_dict is not c_result.dict or \
+                self._c_style.doc.dict is not c_result.dict or \
+                input_doc._c_doc.dict is not c_result.dict:
+            with nogil:
+                if c_dict is not c_result.dict:
+                    fixThreadDictNames(<xmlNode*>c_result,
+                                       c_dict, c_result.dict)
+                if self._c_style.doc.dict is not c_result.dict:
+                    fixThreadDictNames(<xmlNode*>c_result,
+                                       self._c_style.doc.dict, c_result.dict)
+                if input_doc._c_doc.dict is not c_result.dict:
+                    fixThreadDictNames(<xmlNode*>c_result,
+                                       input_doc._c_doc.dict, c_result.dict)
+        xmlparser.xmlDictFree(c_dict)
+
+        return _xsltResultTreeFactory(result_doc, self, profile_doc)
+
+    cdef xmlDoc* _run_transform(self, xmlDoc* c_input_doc,
+                                const_char** params, _XSLTContext context,
+                                xslt.xsltTransformContext* transform_ctxt):
+        cdef xmlDoc* c_result
+        xslt.xsltSetTransformErrorFunc(transform_ctxt, <void*>self._error_log,
+                                       <xmlerror.xmlGenericErrorFunc>_receiveXSLTError)
+        if self._access_control is not None:
+            self._access_control._register_in_context(transform_ctxt)
+        with self._error_log, nogil:
+            orig_loader = _register_document_loader()
+            c_result = xslt.xsltApplyStylesheetUser(
+                self._c_style, c_input_doc, params, NULL, NULL, transform_ctxt)
+            _reset_document_loader(orig_loader)
+        return c_result
+
+
+cdef _convert_xslt_parameters(xslt.xsltTransformContext* transform_ctxt,
+                              dict parameters, const_char*** params_ptr):
+    cdef Py_ssize_t i, parameter_count
+    cdef const_char** params
+    cdef tree.xmlDict* c_dict = transform_ctxt.dict
+    params_ptr[0] = NULL
+    parameter_count = len(parameters)
+    if parameter_count == 0:
+        return
+    # allocate space for parameters
+    # * 2 as we want an entry for both key and value,
+    # and + 1 as array is NULL terminated
+    params = <const_char**>python.lxml_malloc(parameter_count * 2 + 1, sizeof(const_char*))
+    if not params:
+        raise MemoryError()
+    try:
+        i = 0
+        for key, value in parameters.iteritems():
+            k = _utf8(key)
+            if isinstance(value, _XSLTQuotedStringParam):
+                v = (<_XSLTQuotedStringParam>value).strval
+                xslt.xsltQuoteOneUserParam(
+                    transform_ctxt, _xcstr(k), _xcstr(v))
+            else:
+                if isinstance(value, XPath):
+                    v = (<XPath>value)._path
+                else:
+                    v = _utf8(value)
+                params[i] = <const_char*>tree.xmlDictLookup(c_dict, _xcstr(k), len(k))
+                i += 1
+                params[i] = <const_char*>tree.xmlDictLookup(c_dict, _xcstr(v), len(v))
+                i += 1
+    except:
+        python.lxml_free(params)
+        raise
+    params[i] = NULL
+    params_ptr[0] = params
+
+cdef XSLT _copyXSLT(XSLT stylesheet):
+    cdef XSLT new_xslt
+    cdef xmlDoc* c_doc
+    assert stylesheet._c_style is not NULL, "XSLT stylesheet not initialised"
+    new_xslt = XSLT.__new__(XSLT)
+    new_xslt._access_control = stylesheet._access_control
+    new_xslt._error_log = _ErrorLog()
+    new_xslt._context = stylesheet._context._copy()
+
+    new_xslt._xslt_resolver_context = stylesheet._xslt_resolver_context._copy()
+    new_xslt._xslt_resolver_context._c_style_doc = _copyDoc(
+        stylesheet._xslt_resolver_context._c_style_doc, 1)
+
+    c_doc = _copyDoc(stylesheet._c_style.doc, 1)
+    new_xslt._c_style = xslt.xsltParseStylesheetDoc(c_doc)
+    if new_xslt._c_style is NULL:
+        tree.xmlFreeDoc(c_doc)
+        raise MemoryError()
+
+    return new_xslt
+
+@cython.final
+cdef class _XSLTResultTree(_ElementTree):
+    """The result of an XSLT evaluation.
+
+    Use ``str()`` or ``bytes()`` (or ``unicode()`` in Python 2.x) to serialise to a string,
+    and the ``.write_output()`` method to write serialise to a file.
+    """
+    cdef XSLT _xslt
+    cdef _Document _profile
+    cdef xmlChar* _buffer
+    cdef Py_ssize_t _buffer_len
+    cdef Py_ssize_t _buffer_refcnt
+
+    def write_output(self, file, *, compression=0):
+        """write_output(self, file, *, compression=0)
+
+        Serialise the XSLT output to a file or file-like object.
+
+        As opposed to the generic ``.write()`` method, ``.write_output()`` serialises
+        the result as defined by the ``<xsl:output>`` tag.
+        """
+        cdef _FilelikeWriter writer = None
+        cdef _Document doc
+        cdef int r, rclose, c_compression
+        cdef const_xmlChar* c_encoding = NULL
+        cdef tree.xmlOutputBuffer* c_buffer
+
+        if self._context_node is not None:
+            doc = self._context_node._doc
+        else:
+            doc = None
+        if doc is None:
+            doc = self._doc
+            if doc is None:
+                raise XSLTSaveError("No document to serialise")
+        c_compression = compression or 0
+        xslt.LXML_GET_XSLT_ENCODING(c_encoding, self._xslt._c_style)
+        writer = _create_output_buffer(file, <const_char*>c_encoding, compression, &c_buffer, close=False)
+        if writer is None:
+            with nogil:
+                r = xslt.xsltSaveResultTo(c_buffer, doc._c_doc, self._xslt._c_style)
+                rclose = tree.xmlOutputBufferClose(c_buffer)
+        else:
+            r = xslt.xsltSaveResultTo(c_buffer, doc._c_doc, self._xslt._c_style)
+            rclose = tree.xmlOutputBufferClose(c_buffer)
+        if writer is not None:
+            writer._exc_context._raise_if_stored()
+        if r < 0 or rclose == -1:
+            python.PyErr_SetFromErrno(IOError)  # raises IOError
+
+    cdef _saveToStringAndSize(self, xmlChar** s, int* l):
+        cdef _Document doc
+        cdef int r
+        if self._context_node is not None:
+            doc = self._context_node._doc
+        else:
+            doc = None
+        if doc is None:
+            doc = self._doc
+            if doc is None:
+                s[0] = NULL
+                return
+        with nogil:
+            r = xslt.xsltSaveResultToString(s, l, doc._c_doc,
+                                            self._xslt._c_style)
+        if r == -1:
+            raise MemoryError()
+
+    def __str__(self):
+        cdef xmlChar* encoding
+        cdef xmlChar* s = NULL
+        cdef int l = 0
+        self._saveToStringAndSize(&s, &l)
+        if s is NULL:
+            return ''
+        encoding = self._xslt._c_style.encoding
+        try:
+            if encoding is NULL:
+                result = s[:l].decode('UTF-8')
+            else:
+                result = s[:l].decode(encoding)
+        finally:
+            tree.xmlFree(s)
+        return _stripEncodingDeclaration(result)
+
+    def __getbuffer__(self, Py_buffer* buffer, int flags):
+        cdef int l = 0
+        if buffer is NULL:
+            return
+        if self._buffer is NULL or flags & python.PyBUF_WRITABLE:
+            self._saveToStringAndSize(<xmlChar**>&buffer.buf, &l)
+            buffer.len = l
+            if self._buffer is NULL and not flags & python.PyBUF_WRITABLE:
+                self._buffer = <xmlChar*>buffer.buf
+                self._buffer_len = l
+                self._buffer_refcnt = 1
+        else:
+            buffer.buf = self._buffer
+            buffer.len = self._buffer_len
+            self._buffer_refcnt += 1
+        if flags & python.PyBUF_WRITABLE:
+            buffer.readonly = 0
+        else:
+            buffer.readonly = 1
+        if flags & python.PyBUF_FORMAT:
+            buffer.format = "B"
+        else:
+            buffer.format = NULL
+        buffer.ndim = 0
+        buffer.shape = NULL
+        buffer.strides = NULL
+        buffer.suboffsets = NULL
+        buffer.itemsize = 1
+        buffer.internal = NULL
+        if buffer.obj is not self: # set by Cython?
+            buffer.obj = self
+
+    def __releasebuffer__(self, Py_buffer* buffer):
+        if buffer is NULL:
+            return
+        if <xmlChar*>buffer.buf is self._buffer:
+            self._buffer_refcnt -= 1
+            if self._buffer_refcnt == 0:
+                tree.xmlFree(<char*>self._buffer)
+                self._buffer = NULL
+        else:
+            tree.xmlFree(<char*>buffer.buf)
+        buffer.buf = NULL
+
+    property xslt_profile:
+        """Return an ElementTree with profiling data for the stylesheet run.
+        """
+        def __get__(self):
+            cdef object root
+            if self._profile is None:
+                return None
+            root = self._profile.getroot()
+            if root is None:
+                return None
+            return ElementTree(root)
+
+        def __del__(self):
+            self._profile = None
+
+cdef _xsltResultTreeFactory(_Document doc, XSLT xslt, _Document profile):
+    cdef _XSLTResultTree result
+    result = <_XSLTResultTree>_newElementTree(doc, None, _XSLTResultTree)
+    result._xslt = xslt
+    result._profile = profile
+    return result
+
+# functions like "output" and "write" are a potential security risk, but we
+# rely on the user to configure XSLTAccessControl as needed
+xslt.xsltRegisterAllExtras()
+
+# enable EXSLT support for XSLT
+xslt.exsltRegisterAll()
+
+
+################################################################################
+# XSLT PI support
+
+cdef object _RE_PI_HREF = re.compile(r'\s+href\s*=\s*(?:\'([^\']*)\'|"([^"]*)")')
+cdef object _FIND_PI_HREF = _RE_PI_HREF.findall
+cdef object _REPLACE_PI_HREF = _RE_PI_HREF.sub
+cdef XPath __findStylesheetByID = None
+
+cdef _findStylesheetByID(_Document doc, id):
+    global __findStylesheetByID
+    if __findStylesheetByID is None:
+        __findStylesheetByID = XPath(
+            "//xsl:stylesheet[@xml:id = $id]",
+            namespaces={"xsl" : "http://www.w3.org/1999/XSL/Transform"})
+    return __findStylesheetByID(doc, id=id)
+
+cdef class _XSLTProcessingInstruction(PIBase):
+    def parseXSL(self, parser=None):
+        """parseXSL(self, parser=None)
+
+        Try to parse the stylesheet referenced by this PI and return
+        an ElementTree for it.  If the stylesheet is embedded in the
+        same document (referenced via xml:id), find and return an
+        ElementTree for the stylesheet Element.
+
+        The optional ``parser`` keyword argument can be passed to specify the
+        parser used to read from external stylesheet URLs.
+        """
+        cdef _Document result_doc
+        cdef _Element  result_node
+        cdef bytes href_utf
+        cdef const_xmlChar* c_href
+        cdef xmlAttr* c_attr
+        _assertValidNode(self)
+        if self._c_node.content is NULL:
+            raise ValueError, "PI lacks content"
+        hrefs = _FIND_PI_HREF(' ' + (<unsigned char*>self._c_node.content).decode('UTF-8'))
+        if len(hrefs) != 1:
+            raise ValueError, "malformed PI attributes"
+        hrefs = hrefs[0]
+        href_utf = utf8(hrefs[0] or hrefs[1])
+        c_href = _xcstr(href_utf)
+
+        if c_href[0] != c'#':
+            # normal URL, try to parse from it
+            c_href = tree.xmlBuildURI(
+                c_href,
+                tree.xmlNodeGetBase(self._c_node.doc, self._c_node))
+            if c_href is not NULL:
+                try:
+                    href_utf = <unsigned char*>c_href
+                finally:
+                    tree.xmlFree(<char*>c_href)
+            result_doc = _parseDocumentFromURL(href_utf, parser)
+            return _elementTreeFactory(result_doc, None)
+
+        # ID reference to embedded stylesheet
+        # try XML:ID lookup
+        _assertValidDoc(self._doc)
+        c_href += 1 # skip leading '#'
+        c_attr = tree.xmlGetID(self._c_node.doc, c_href)
+        if c_attr is not NULL and c_attr.doc is self._c_node.doc:
+            result_node = _elementFactory(self._doc, c_attr.parent)
+            return _elementTreeFactory(result_node._doc, result_node)
+
+        # try XPath search
+        root = _findStylesheetByID(self._doc, funicode(c_href))
+        if not root:
+            raise ValueError, "reference to non-existing embedded stylesheet"
+        elif len(root) > 1:
+            raise ValueError, "ambiguous reference to embedded stylesheet"
+        result_node = root[0]
+        return _elementTreeFactory(result_node._doc, result_node)
+
+    def set(self, key, value):
+        """set(self, key, value)
+
+        Supports setting the 'href' pseudo-attribute in the text of
+        the processing instruction.
+        """
+        if key != "href":
+            raise AttributeError, \
+                "only setting the 'href' attribute is supported on XSLT-PIs"
+        if value is None:
+            attrib = ""
+        elif '"' in value or '>' in value:
+            raise ValueError, "Invalid URL, must not contain '\"' or '>'"
+        else:
+            attrib = f' href="{value}"'
+        text = ' ' + self.text
+        if _FIND_PI_HREF(text):
+            self.text = _REPLACE_PI_HREF(attrib, text)
+        else:
+            self.text = text + attrib