week06

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

@@ -0,0 +1,487 @@
+# XPath evaluation
+
+class XPathSyntaxError(LxmlSyntaxError, XPathError):
+    pass
+
+################################################################################
+# XPath
+
+cdef object _XPATH_SYNTAX_ERRORS = (
+    xmlerror.XML_XPATH_NUMBER_ERROR,
+    xmlerror.XML_XPATH_UNFINISHED_LITERAL_ERROR,
+    xmlerror.XML_XPATH_VARIABLE_REF_ERROR,
+    xmlerror.XML_XPATH_INVALID_PREDICATE_ERROR,
+    xmlerror.XML_XPATH_UNCLOSED_ERROR,
+    xmlerror.XML_XPATH_INVALID_CHAR_ERROR
+)
+
+cdef object _XPATH_EVAL_ERRORS = (
+    xmlerror.XML_XPATH_UNDEF_VARIABLE_ERROR,
+    xmlerror.XML_XPATH_UNDEF_PREFIX_ERROR,
+    xmlerror.XML_XPATH_UNKNOWN_FUNC_ERROR,
+    xmlerror.XML_XPATH_INVALID_OPERAND,
+    xmlerror.XML_XPATH_INVALID_TYPE,
+    xmlerror.XML_XPATH_INVALID_ARITY,
+    xmlerror.XML_XPATH_INVALID_CTXT_SIZE,
+    xmlerror.XML_XPATH_INVALID_CTXT_POSITION
+)
+
+cdef int _register_xpath_function(void* ctxt, name_utf, ns_utf) noexcept:
+    if ns_utf is None:
+        return xpath.xmlXPathRegisterFunc(
+            <xpath.xmlXPathContext*>ctxt, _xcstr(name_utf),
+            _xpath_function_call)
+    else:
+        return xpath.xmlXPathRegisterFuncNS(
+            <xpath.xmlXPathContext*>ctxt, _xcstr(name_utf), _xcstr(ns_utf),
+            _xpath_function_call)
+
+cdef int _unregister_xpath_function(void* ctxt, name_utf, ns_utf) noexcept:
+    if ns_utf is None:
+        return xpath.xmlXPathRegisterFunc(
+            <xpath.xmlXPathContext*>ctxt, _xcstr(name_utf), NULL)
+    else:
+        return xpath.xmlXPathRegisterFuncNS(
+            <xpath.xmlXPathContext*>ctxt, _xcstr(name_utf), _xcstr(ns_utf), NULL)
+
+
+@cython.final
+@cython.internal
+cdef class _XPathContext(_BaseContext):
+    cdef object _variables
+    def __init__(self, namespaces, extensions, error_log, enable_regexp, variables,
+                 build_smart_strings):
+        self._variables = variables
+        _BaseContext.__init__(self, namespaces, extensions, error_log, enable_regexp,
+                              build_smart_strings)
+
+    cdef set_context(self, xpath.xmlXPathContext* xpathCtxt):
+        self._set_xpath_context(xpathCtxt)
+        # This would be a good place to set up the XPath parser dict, but
+        # we cannot use the current thread dict as we do not know which
+        # thread will execute the XPath evaluator - so, no dict for now.
+        self.registerLocalNamespaces()
+        self.registerLocalFunctions(xpathCtxt, _register_xpath_function)
+
+    cdef register_context(self, _Document doc):
+        self._register_context(doc)
+        self.registerGlobalNamespaces()
+        self.registerGlobalFunctions(self._xpathCtxt, _register_xpath_function)
+        self.registerExsltFunctions()
+        if self._variables is not None:
+            self.registerVariables(self._variables)
+
+    cdef unregister_context(self):
+        self.unregisterGlobalFunctions(
+            self._xpathCtxt, _unregister_xpath_function)
+        self.unregisterGlobalNamespaces()
+        xpath.xmlXPathRegisteredVariablesCleanup(self._xpathCtxt)
+        self._cleanup_context()
+
+    cdef void registerExsltFunctions(self) noexcept:
+        if xslt.LIBXSLT_VERSION < 10125:
+            # we'd only execute dummy functions anyway
+            return
+        tree.xmlHashScan(
+            self._xpathCtxt.nsHash, _registerExsltFunctionsForNamespaces,
+            self._xpathCtxt)
+
+    cdef registerVariables(self, variable_dict):
+        for name, value in variable_dict.items():
+            name_utf = self._to_utf(name)
+            xpath.xmlXPathRegisterVariable(
+                self._xpathCtxt, _xcstr(name_utf), _wrapXPathObject(value, None, None))
+
+    cdef registerVariable(self, name, value):
+        name_utf = self._to_utf(name)
+        xpath.xmlXPathRegisterVariable(
+            self._xpathCtxt, _xcstr(name_utf), _wrapXPathObject(value, None, None))
+
+
+cdef void _registerExsltFunctionsForNamespaces(
+        void* _c_href, void* _ctxt, const_xmlChar* c_prefix) noexcept:
+    c_href = <const_xmlChar*> _c_href
+    ctxt = <xpath.xmlXPathContext*> _ctxt
+
+    if tree.xmlStrcmp(c_href, xslt.EXSLT_DATE_NAMESPACE) == 0:
+        xslt.exsltDateXpathCtxtRegister(ctxt, c_prefix)
+    elif tree.xmlStrcmp(c_href, xslt.EXSLT_SETS_NAMESPACE) == 0:
+        xslt.exsltSetsXpathCtxtRegister(ctxt, c_prefix)
+    elif tree.xmlStrcmp(c_href, xslt.EXSLT_MATH_NAMESPACE) == 0:
+        xslt.exsltMathXpathCtxtRegister(ctxt, c_prefix)
+    elif tree.xmlStrcmp(c_href, xslt.EXSLT_STRINGS_NAMESPACE) == 0:
+        xslt.exsltStrXpathCtxtRegister(ctxt, c_prefix)
+
+
+cdef class _XPathEvaluatorBase:
+    cdef xpath.xmlXPathContext* _xpathCtxt
+    cdef _XPathContext _context
+    cdef python.PyThread_type_lock _eval_lock
+    cdef _ErrorLog _error_log
+    def __cinit__(self):
+        self._xpathCtxt = NULL
+        if config.ENABLE_THREADING:
+            self._eval_lock = python.PyThread_allocate_lock()
+            if self._eval_lock is NULL:
+                raise MemoryError()
+        self._error_log = _ErrorLog()
+
+    def __init__(self, namespaces, extensions, enable_regexp,
+                 smart_strings):
+        self._context = _XPathContext(namespaces, extensions, self._error_log,
+                                      enable_regexp, None, smart_strings)
+
+    @property
+    def error_log(self):
+        assert self._error_log is not None, "XPath evaluator not initialised"
+        return self._error_log.copy()
+
+    def __dealloc__(self):
+        if self._xpathCtxt is not NULL:
+            xpath.xmlXPathFreeContext(self._xpathCtxt)
+        if config.ENABLE_THREADING:
+            if self._eval_lock is not NULL:
+                python.PyThread_free_lock(self._eval_lock)
+
+    cdef set_context(self, xpath.xmlXPathContext* xpathCtxt):
+        self._xpathCtxt = xpathCtxt
+        self._context.set_context(xpathCtxt)
+
+    cdef bint _checkAbsolutePath(self, char* path) noexcept:
+        cdef char c
+        if path is NULL:
+            return 0
+        c = path[0]
+        while c == c' ' or c == c'\t':
+            path = path + 1
+            c = path[0]
+        return c == c'/'
+
+    @cython.final
+    cdef int _lock(self) except -1:
+        cdef int result
+        if config.ENABLE_THREADING and self._eval_lock != NULL:
+            with nogil:
+                result = python.PyThread_acquire_lock(
+                    self._eval_lock, python.WAIT_LOCK)
+            if result == 0:
+                raise XPathError, "XPath evaluator locking failed"
+        return 0
+
+    @cython.final
+    cdef void _unlock(self) noexcept:
+        if config.ENABLE_THREADING and self._eval_lock != NULL:
+            python.PyThread_release_lock(self._eval_lock)
+
+    cdef _build_parse_error(self):
+        cdef _BaseErrorLog entries
+        entries = self._error_log.filter_types(_XPATH_SYNTAX_ERRORS)
+        if entries:
+            message = entries._buildExceptionMessage(None)
+            if message is not None:
+                return XPathSyntaxError(message, self._error_log)
+        return XPathSyntaxError(
+            self._error_log._buildExceptionMessage("Error in xpath expression"),
+            self._error_log)
+
+    cdef _build_eval_error(self):
+        cdef _BaseErrorLog entries
+        entries = self._error_log.filter_types(_XPATH_EVAL_ERRORS)
+        if not entries:
+            entries = self._error_log.filter_types(_XPATH_SYNTAX_ERRORS)
+        if entries:
+            message = entries._buildExceptionMessage(None)
+            if message is not None:
+                return XPathEvalError(message, self._error_log)
+        return XPathEvalError(
+            self._error_log._buildExceptionMessage("Error in xpath expression"),
+            self._error_log)
+
+    cdef object _handle_result(self, xpath.xmlXPathObject* xpathObj, _Document doc):
+        if self._context._exc._has_raised():
+            if xpathObj is not NULL:
+                _freeXPathObject(xpathObj)
+                xpathObj = NULL
+            self._context._release_temp_refs()
+            self._context._exc._raise_if_stored()
+
+        if xpathObj is NULL:
+            self._context._release_temp_refs()
+            raise self._build_eval_error()
+
+        try:
+            result = _unwrapXPathObject(xpathObj, doc, self._context)
+        finally:
+            _freeXPathObject(xpathObj)
+            self._context._release_temp_refs()
+
+        return result
+
+
+cdef class XPathElementEvaluator(_XPathEvaluatorBase):
+    """XPathElementEvaluator(self, element, namespaces=None, extensions=None, regexp=True, smart_strings=True)
+    Create an XPath evaluator for an element.
+
+    Absolute XPath expressions (starting with '/') will be evaluated against
+    the ElementTree as returned by getroottree().
+
+    Additional namespace declarations can be passed with the
+    'namespace' keyword argument.  EXSLT regular expression support
+    can be disabled with the 'regexp' boolean keyword (defaults to
+    True).  Smart strings will be returned for string results unless
+    you pass ``smart_strings=False``.
+    """
+    cdef _Element _element
+    def __init__(self, _Element element not None, *, namespaces=None,
+                 extensions=None, regexp=True, smart_strings=True):
+        cdef xpath.xmlXPathContext* xpathCtxt
+        cdef int ns_register_status
+        cdef _Document doc
+        _assertValidNode(element)
+        _assertValidDoc(element._doc)
+        self._element = element
+        doc = element._doc
+        _XPathEvaluatorBase.__init__(self, namespaces, extensions,
+                                     regexp, smart_strings)
+        xpathCtxt = xpath.xmlXPathNewContext(doc._c_doc)
+        if xpathCtxt is NULL:
+            raise MemoryError()
+        self.set_context(xpathCtxt)
+
+    def register_namespace(self, prefix, uri):
+        """Register a namespace with the XPath context.
+        """
+        assert self._xpathCtxt is not NULL, "XPath context not initialised"
+        self._context.addNamespace(prefix, uri)
+
+    def register_namespaces(self, namespaces):
+        """Register a prefix -> uri dict.
+        """
+        assert self._xpathCtxt is not NULL, "XPath context not initialised"
+        for prefix, uri in namespaces.items():
+            self._context.addNamespace(prefix, uri)
+
+    def __call__(self, _path, **_variables):
+        """__call__(self, _path, **_variables)
+
+        Evaluate an XPath expression on the document.
+
+        Variables may be provided as keyword arguments.  Note that namespaces
+        are currently not supported for variables.
+
+        Absolute XPath expressions (starting with '/') will be evaluated
+        against the ElementTree as returned by getroottree().
+        """
+        cdef xpath.xmlXPathObject*  xpathObj
+        cdef _Document doc
+        assert self._xpathCtxt is not NULL, "XPath context not initialised"
+        path = _utf8(_path)
+        doc = self._element._doc
+
+        self._lock()
+        self._xpathCtxt.node = self._element._c_node
+        try:
+            self._context.register_context(doc)
+            self._context.registerVariables(_variables)
+            c_path = _xcstr(path)
+            with nogil:
+                xpathObj = xpath.xmlXPathEvalExpression(
+                    c_path, self._xpathCtxt)
+            result = self._handle_result(xpathObj, doc)
+        finally:
+            self._context.unregister_context()
+            self._unlock()
+
+        return result
+
+
+cdef class XPathDocumentEvaluator(XPathElementEvaluator):
+    """XPathDocumentEvaluator(self, etree, namespaces=None, extensions=None, regexp=True, smart_strings=True)
+    Create an XPath evaluator for an ElementTree.
+
+    Additional namespace declarations can be passed with the
+    'namespace' keyword argument.  EXSLT regular expression support
+    can be disabled with the 'regexp' boolean keyword (defaults to
+    True).  Smart strings will be returned for string results unless
+    you pass ``smart_strings=False``.
+    """
+    def __init__(self, _ElementTree etree not None, *, namespaces=None,
+                 extensions=None, regexp=True, smart_strings=True):
+        XPathElementEvaluator.__init__(
+            self, etree._context_node, namespaces=namespaces, 
+            extensions=extensions, regexp=regexp,
+            smart_strings=smart_strings)
+
+    def __call__(self, _path, **_variables):
+        """__call__(self, _path, **_variables)
+
+        Evaluate an XPath expression on the document.
+
+        Variables may be provided as keyword arguments.  Note that namespaces
+        are currently not supported for variables.
+        """
+        cdef xpath.xmlXPathObject*  xpathObj
+        cdef xmlDoc* c_doc
+        cdef _Document doc
+        assert self._xpathCtxt is not NULL, "XPath context not initialised"
+        path = _utf8(_path)
+        doc = self._element._doc
+
+        self._lock()
+        try:
+            self._context.register_context(doc)
+            c_doc = _fakeRootDoc(doc._c_doc, self._element._c_node)
+            try:
+                self._context.registerVariables(_variables)
+                c_path = _xcstr(path)
+                with nogil:
+                    self._xpathCtxt.doc  = c_doc
+                    self._xpathCtxt.node = tree.xmlDocGetRootElement(c_doc)
+                    xpathObj = xpath.xmlXPathEvalExpression(
+                        c_path, self._xpathCtxt)
+                result = self._handle_result(xpathObj, doc)
+            finally:
+                _destroyFakeDoc(doc._c_doc, c_doc)
+                self._context.unregister_context()
+        finally:
+            self._unlock()
+
+        return result
+
+
+def XPathEvaluator(etree_or_element, *, namespaces=None, extensions=None,
+                   regexp=True, smart_strings=True):
+    """XPathEvaluator(etree_or_element, namespaces=None, extensions=None, regexp=True, smart_strings=True)
+
+    Creates an XPath evaluator for an ElementTree or an Element.
+
+    The resulting object can be called with an XPath expression as argument
+    and XPath variables provided as keyword arguments.
+
+    Additional namespace declarations can be passed with the
+    'namespace' keyword argument.  EXSLT regular expression support
+    can be disabled with the 'regexp' boolean keyword (defaults to
+    True).  Smart strings will be returned for string results unless
+    you pass ``smart_strings=False``.
+    """
+    if isinstance(etree_or_element, _ElementTree):
+        return XPathDocumentEvaluator(
+            etree_or_element, namespaces=namespaces,
+            extensions=extensions, regexp=regexp, smart_strings=smart_strings)
+    else:
+        return XPathElementEvaluator(
+            etree_or_element, namespaces=namespaces,
+            extensions=extensions, regexp=regexp, smart_strings=smart_strings)
+
+
+cdef class XPath(_XPathEvaluatorBase):
+    """XPath(self, path, namespaces=None, extensions=None, regexp=True, smart_strings=True)
+    A compiled XPath expression that can be called on Elements and ElementTrees.
+
+    Besides the XPath expression, you can pass prefix-namespace
+    mappings and extension functions to the constructor through the
+    keyword arguments ``namespaces`` and ``extensions``.  EXSLT
+    regular expression support can be disabled with the 'regexp'
+    boolean keyword (defaults to True).  Smart strings will be
+    returned for string results unless you pass
+    ``smart_strings=False``.
+    """
+    cdef xpath.xmlXPathCompExpr* _xpath
+    cdef bytes _path
+    def __cinit__(self):
+        self._xpath = NULL
+
+    def __init__(self, path, *, namespaces=None, extensions=None,
+                 regexp=True, smart_strings=True):
+        cdef xpath.xmlXPathContext* xpathCtxt
+        _XPathEvaluatorBase.__init__(self, namespaces, extensions,
+                                     regexp, smart_strings)
+        self._path = _utf8(path)
+        xpathCtxt = xpath.xmlXPathNewContext(NULL)
+        if xpathCtxt is NULL:
+            raise MemoryError()
+        self.set_context(xpathCtxt)
+        self._xpath = xpath.xmlXPathCtxtCompile(xpathCtxt, _xcstr(self._path))
+        if self._xpath is NULL:
+            raise self._build_parse_error()
+
+    def __call__(self, _etree_or_element, **_variables):
+        "__call__(self, _etree_or_element, **_variables)"
+        cdef xpath.xmlXPathObject*  xpathObj
+        cdef _Document document
+        cdef _Element element
+
+        assert self._xpathCtxt is not NULL, "XPath context not initialised"
+        document = _documentOrRaise(_etree_or_element)
+        element  = _rootNodeOrRaise(_etree_or_element)
+
+        self._lock()
+        self._xpathCtxt.doc  = document._c_doc
+        self._xpathCtxt.node = element._c_node
+
+        try:
+            self._context.register_context(document)
+            self._context.registerVariables(_variables)
+            with nogil:
+                xpathObj = xpath.xmlXPathCompiledEval(
+                    self._xpath, self._xpathCtxt)
+            result = self._handle_result(xpathObj, document)
+        finally:
+            self._context.unregister_context()
+            self._unlock()
+        return result
+
+    @property
+    def path(self):
+        """The literal XPath expression.
+        """
+        return self._path.decode('UTF-8')
+
+    def __dealloc__(self):
+        if self._xpath is not NULL:
+            xpath.xmlXPathFreeCompExpr(self._xpath)
+
+    def __repr__(self):
+        return self.path
+
+
+cdef object _replace_strings = re.compile(b'("[^"]*")|(\'[^\']*\')').sub
+cdef object _find_namespaces = re.compile(b'({[^}]+})').findall
+
+cdef class ETXPath(XPath):
+    """ETXPath(self, path, extensions=None, regexp=True, smart_strings=True)
+    Special XPath class that supports the ElementTree {uri} notation for namespaces.
+
+    Note that this class does not accept the ``namespace`` keyword
+    argument. All namespaces must be passed as part of the path
+    string.  Smart strings will be returned for string results unless
+    you pass ``smart_strings=False``.
+    """
+    def __init__(self, path, *, extensions=None, regexp=True,
+                 smart_strings=True):
+        path, namespaces = self._nsextract_path(path)
+        XPath.__init__(self, path, namespaces=namespaces,
+                       extensions=extensions, regexp=regexp,
+                       smart_strings=smart_strings)
+
+    cdef _nsextract_path(self, path):
+        # replace {namespaces} by new prefixes
+        cdef dict namespaces = {}
+        cdef list namespace_defs = []
+        cdef int i
+        path_utf = _utf8(path)
+        stripped_path = _replace_strings(b'', path_utf) # remove string literals
+        i = 1
+        for namespace_def in _find_namespaces(stripped_path):
+            if namespace_def not in namespace_defs:
+                prefix = python.PyBytes_FromFormat("__xpp%02d", i)
+                i += 1
+                namespace_defs.append(namespace_def)
+                namespace = namespace_def[1:-1] # remove '{}'
+                namespace = (<bytes>namespace).decode('utf8')
+                namespaces[prefix.decode('utf8')] = namespace
+                prefix_str = prefix + b':'
+                # FIXME: this also replaces {namespaces} within strings!
+                path_utf = path_utf.replace(namespace_def, prefix_str)
+        path = path_utf.decode('utf8')
+        return path, namespaces