week06

env/lib/python3.12/site-packages/lxml/sax.py

@@ -0,0 +1,275 @@
+# cython: language_level=2
+
+"""
+SAX-based adapter to copy trees from/to the Python standard library.
+
+Use the `ElementTreeContentHandler` class to build an ElementTree from
+SAX events.
+
+Use the `ElementTreeProducer` class or the `saxify()` function to fire
+the SAX events of an ElementTree against a SAX ContentHandler.
+
+See https://lxml.de/sax.html
+"""
+
+
+from xml.sax.handler import ContentHandler
+from lxml import etree
+from lxml.etree import ElementTree, SubElement
+from lxml.etree import Comment, ProcessingInstruction
+
+
+class SaxError(etree.LxmlError):
+    """General SAX error.
+    """
+
+
+def _getNsTag(tag):
+    if tag[0] == '{':
+        return tuple(tag[1:].split('}', 1))
+    else:
+        return None, tag
+
+
+class ElementTreeContentHandler(ContentHandler):
+    """Build an lxml ElementTree from SAX events.
+    """
+    def __init__(self, makeelement=None):
+        ContentHandler.__init__(self)
+        self._root = None
+        self._root_siblings = []
+        self._element_stack = []
+        self._default_ns = None
+        self._ns_mapping = { None : [None] }
+        self._new_mappings = {}
+        if makeelement is None:
+            makeelement = etree.Element
+        self._makeelement = makeelement
+
+    def _get_etree(self):
+        "Contains the generated ElementTree after parsing is finished."
+        return ElementTree(self._root)
+
+    etree = property(_get_etree, doc=_get_etree.__doc__)
+
+    def setDocumentLocator(self, locator):
+        pass
+
+    def startDocument(self):
+        pass
+
+    def endDocument(self):
+        pass
+
+    def startPrefixMapping(self, prefix, uri):
+        self._new_mappings[prefix] = uri
+        try:
+            self._ns_mapping[prefix].append(uri)
+        except KeyError:
+            self._ns_mapping[prefix] = [uri]
+        if prefix is None:
+            self._default_ns = uri
+
+    def endPrefixMapping(self, prefix):
+        ns_uri_list = self._ns_mapping[prefix]
+        ns_uri_list.pop()
+        if prefix is None:
+            self._default_ns = ns_uri_list[-1]
+
+    def _buildTag(self, ns_name_tuple):
+        ns_uri, local_name = ns_name_tuple
+        if ns_uri:
+            el_tag = "{%s}%s" % ns_name_tuple
+        elif self._default_ns:
+            el_tag = "{%s}%s" % (self._default_ns, local_name)
+        else:
+            el_tag = local_name
+        return el_tag
+
+    def startElementNS(self, ns_name, qname, attributes=None):
+        el_name = self._buildTag(ns_name)
+        if attributes:
+            attrs = {}
+            try:
+                iter_attributes = attributes.iteritems()
+            except AttributeError:
+                iter_attributes = attributes.items()
+
+            for name_tuple, value in iter_attributes:
+                if name_tuple[0]:
+                    attr_name = "{%s}%s" % name_tuple
+                else:
+                    attr_name = name_tuple[1]
+                attrs[attr_name] = value
+        else:
+            attrs = None
+
+        element_stack = self._element_stack
+        if self._root is None:
+            element = self._root = \
+                      self._makeelement(el_name, attrs, self._new_mappings)
+            if self._root_siblings and hasattr(element, 'addprevious'):
+                for sibling in self._root_siblings:
+                    element.addprevious(sibling)
+            del self._root_siblings[:]
+        else:
+            element = SubElement(element_stack[-1], el_name,
+                                 attrs, self._new_mappings)
+        element_stack.append(element)
+
+        self._new_mappings.clear()
+
+    def processingInstruction(self, target, data):
+        pi = ProcessingInstruction(target, data)
+        if self._root is None:
+            self._root_siblings.append(pi)
+        else:
+            self._element_stack[-1].append(pi)
+
+    def endElementNS(self, ns_name, qname):
+        element = self._element_stack.pop()
+        el_tag = self._buildTag(ns_name)
+        if el_tag != element.tag:
+            raise SaxError("Unexpected element closed: " + el_tag)
+
+    def startElement(self, name, attributes=None):
+        if attributes:
+            attributes = {(None, k): v for k, v in attributes.items()}
+        self.startElementNS((None, name), name, attributes)
+
+    def endElement(self, name):
+        self.endElementNS((None, name), name)
+
+    def characters(self, data):
+        last_element = self._element_stack[-1]
+        try:
+            # if there already is a child element, we must append to its tail
+            last_element = last_element[-1]
+            last_element.tail = (last_element.tail or '') + data
+        except IndexError:
+            # otherwise: append to the text
+            last_element.text = (last_element.text or '') + data
+
+    ignorableWhitespace = characters
+
+
+class ElementTreeProducer:
+    """Produces SAX events for an element and children.
+    """
+    def __init__(self, element_or_tree, content_handler):
+        try:
+            element = element_or_tree.getroot()
+        except AttributeError:
+            element = element_or_tree
+        self._element = element
+        self._content_handler = content_handler
+        from xml.sax.xmlreader import AttributesNSImpl as attr_class
+        self._attr_class = attr_class
+        self._empty_attributes = attr_class({}, {})
+
+    def saxify(self):
+        self._content_handler.startDocument()
+
+        element = self._element
+        if hasattr(element, 'getprevious'):
+            siblings = []
+            sibling = element.getprevious()
+            while getattr(sibling, 'tag', None) is ProcessingInstruction:
+                siblings.append(sibling)
+                sibling = sibling.getprevious()
+            for sibling in siblings[::-1]:
+                self._recursive_saxify(sibling, {})
+
+        self._recursive_saxify(element, {})
+
+        if hasattr(element, 'getnext'):
+            sibling = element.getnext()
+            while getattr(sibling, 'tag', None) is ProcessingInstruction:
+                self._recursive_saxify(sibling, {})
+                sibling = sibling.getnext()
+
+        self._content_handler.endDocument()
+
+    def _recursive_saxify(self, element, parent_nsmap):
+        content_handler = self._content_handler
+        tag = element.tag
+        if tag is Comment or tag is ProcessingInstruction:
+            if tag is ProcessingInstruction:
+                content_handler.processingInstruction(
+                    element.target, element.text)
+            tail = element.tail
+            if tail:
+                content_handler.characters(tail)
+            return
+
+        element_nsmap = element.nsmap
+        new_prefixes = []
+        if element_nsmap != parent_nsmap:
+            # There have been updates to the namespace
+            for prefix, ns_uri in element_nsmap.items():
+                if parent_nsmap.get(prefix) != ns_uri:
+                    new_prefixes.append( (prefix, ns_uri) )
+
+        attribs = element.items()
+        if attribs:
+            attr_values = {}
+            attr_qnames = {}
+            for attr_ns_name, value in attribs:
+                attr_ns_tuple = _getNsTag(attr_ns_name)
+                attr_values[attr_ns_tuple] = value
+                attr_qnames[attr_ns_tuple] = self._build_qname(
+                    attr_ns_tuple[0], attr_ns_tuple[1], element_nsmap,
+                    preferred_prefix=None, is_attribute=True)
+            sax_attributes = self._attr_class(attr_values, attr_qnames)
+        else:
+            sax_attributes = self._empty_attributes
+
+        ns_uri, local_name = _getNsTag(tag)
+        qname = self._build_qname(
+            ns_uri, local_name, element_nsmap, element.prefix, is_attribute=False)
+
+        for prefix, uri in new_prefixes:
+            content_handler.startPrefixMapping(prefix, uri)
+        content_handler.startElementNS(
+            (ns_uri, local_name), qname, sax_attributes)
+        text = element.text
+        if text:
+            content_handler.characters(text)
+        for child in element:
+            self._recursive_saxify(child, element_nsmap)
+        content_handler.endElementNS((ns_uri, local_name), qname)
+        for prefix, uri in new_prefixes:
+            content_handler.endPrefixMapping(prefix)
+        tail = element.tail
+        if tail:
+            content_handler.characters(tail)
+
+    def _build_qname(self, ns_uri, local_name, nsmap, preferred_prefix, is_attribute):
+        if ns_uri is None:
+            return local_name
+
+        if not is_attribute and nsmap.get(preferred_prefix) == ns_uri:
+            prefix = preferred_prefix
+        else:
+            # Pick the first matching prefix, in alphabetical order.
+            candidates = [
+                pfx for (pfx, uri) in nsmap.items()
+                if pfx is not None and uri == ns_uri
+            ]
+            prefix = (
+                candidates[0] if len(candidates) == 1
+                else min(candidates) if candidates
+                else None
+            )
+
+        if prefix is None:
+            # Default namespace
+            return local_name
+        return prefix + ':' + local_name
+
+
+def saxify(element_or_tree, content_handler):
+    """One-shot helper to generate SAX events from an XML tree and fire
+    them against a SAX ContentHandler.
+    """
+    return ElementTreeProducer(element_or_tree, content_handler).saxify()