ERP5Type: Add XMLUtils.

product/ERP5Type/XMLUtils.py

+from xml.etree.ElementTree import iterparse, Element, TreeBuilder, XMLParser
+from .XMLMatrix import INFINITE_SET
+
+class RestrictedElement(Element):
+  __allow_access_to_unprotected_subobjects__ = 1
+
+class ChildDiscardingElement(RestrictedElement):
+  """
+  Ignores any children added to it.
+
+  Useful to parse large files, so as many-children nodes actually discards
+  them to free memory.
+  """
+  def __init__(self, tag, expected_tag_set):
+    super(ChildDiscardingElement, self).__init__(tag)
+    self.__expected_tag_set = expected_tag_set
+
+  def __single(self, child):
+    if not (
+          isinstance(child, ChildDiscardingElement) or
+          child.tag in self.__expected_tag_set
+        ):
+      raise ValueError('Unexpected discarded tag: %r (inside %r)' % (
+        child.tag,
+        self.tag,
+      ))
+
+  append = __single
+
+  def extend(self, elements):
+    for child in elements:
+      self.__single(child)
+
+  def insert(self, index, element):
+    self.__single(element)
+
+def parseStream(stream, child_discard_set, callback_dict, catchall=None):
+  """
+  stream (opened read stream)
+    Where XML data is read from. Expects a "read" method following the
+    "file" API.
+
+  child_discard_set (anything implementing '__in__')
+    Set of tags whose children should be discarded while parsing.
+
+  callback_dict (dict)
+    Dict of callables per event and tag type, to be called for these
+    combinations when encountered. Expected structure is:
+    {
+      (event, tag): callable(element) -> None,
+    }
+    See xml.etree.ElementTree.iterparse for a list of possible events.
+
+  catchall (None, callable(element) -> None)
+    Callback triggered for all actually triggered events but not declared in
+    callback_dict.
+    If None, a ValueError exception will be raised when an element whose tag is
+    present in child_discard_set receives a non-child-discarding child for
+    which neither "start" nor "end" callback exist.
+  """
+  if catchall is None:
+    catchall = lambda x: None
+    callback_set = set(
+      y for x, y in callback_dict
+      if x in ('start', 'end', None) # None is equivalent to 'end'
+    )
+  else:
+    callback_set = INFINITE_SET
+  def elementFactory(tag, attrs):
+    if tag in child_discard_set:
+      return ChildDiscardingElement(tag, callback_set)
+    return RestrictedElement(tag, attrs)
+  for event, elem in iterparse(
+          stream,
+          events=set([x for x, _ in callback_dict.iterkeys()]),
+          parser=XMLParser(
+            target=TreeBuilder(
+              element_factory=elementFactory,
+            ),
+          ),
+        ):
+    callback_dict.get((event, elem.tag), catchall)(elem)
\ No newline at end of file

product/ERP5Type/__init__.py

@@ -180,6 +180,7 @@ ModuleSecurityInfo('Products.ERP5Type.Constraint').declarePublic('PropertyTypeVa
 ModuleSecurityInfo('Products.ERP5Type.collections').declarePublic('OrderedDict')
 ModuleSecurityInfo('Products.ERP5Type.DiffUtils').declarePublic('DiffFile')
 ModuleSecurityInfo('pprint').declarePublic('pformat', 'pprint')
+ModuleSecurityInfo('Products.ERP5Type.XMLUtils').declarePublic('parseStream')
 
 import zExceptions
 ModuleSecurityInfo('zExceptions').declarePublic(*filter(