Code further generalized II

src/Products/PluginIndexes/KeywordIndex/KeywordIndex.py

@@ -69,7 +69,7 @@ def _index_object(self, documentId, obj, threshold=None, attr=''):
 
         if oldKeywords is _marker:
             # we've got a new document, let's not futz around.
-            if newKeywords in (missing, empty):
+            if self.providesSpecialIndex(newKeywords):
                 self.insertSpecialIndexEntry(newKeywords, documentId)
             else:
                 newKeywords = self.index_objectKeywords(documentId,
@@ -82,6 +82,15 @@ def _index_object(self, documentId, obj, threshold=None, attr=''):
         else:
             # we have an existing entry for this document, and we need
             # to figure out if any of the keywords have actually changed
+            if self.providesSpecialIndex(oldKeywords) and \
+               self.providesSpecialIndex(newKeywords):
+                if oldKeywords == newKeywords:
+                    return 0
+                self.removeSpecialIndexEntry(oldKeywords, documentId)
+                self.insertSpecialIndexEntry(newKeywords, documentId)
+                self._unindex[documentId] = newKeywords
+                return 1
+
             if self.providesSpecialIndex(oldKeywords):
                 self.removeSpecialIndexEntry(oldKeywords, documentId)
                 oldSet = OOSet()
@@ -109,6 +118,9 @@ def _index_object(self, documentId, obj, threshold=None, attr=''):
                     # is indexable?
                     if not newKeywords:
                         return 0
+            else:
+                # return if no diff
+                return 0
 
         self._unindex[documentId] = newKeywords
 

src/Products/PluginIndexes/interfaces.py

@@ -285,8 +285,16 @@ def getIndexNames():
         """ returns index names that are optimized by index """
 
 
-class _SpecialIndexValue(str):
+class SpecialIndexValue(object):
     """generic marker class for values that cannot be indexed regularly"""
+    def __init__(self, name):
+        self.name = name
+
+    def __str__(self):
+        return self.name
+
+    def __repr__(self):
+        return '<{0}: {1}>'.format(self.__class__.__name__, self.name)
 
     def __iter__(self):
         # don't treat _SpecialIndexValue as iterable string
@@ -298,6 +306,9 @@ def __bool__(self):
     # python2.7 backward compatibility
     __nonzero__ = __bool__
 
+    def __lt__(self, other):
+        return self.name < other.name
+
 
 class _IIndexingSpecialValue(Interface):
     """Abstract marker interface to mark indexes which support a
@@ -321,7 +332,7 @@ class IIndexingMissingValue(_IIndexingSpecialValue):
 # `missing` can be used as query term to query
 # for objects the index does not have a value for
 # (like a not defined value)
-missing = _SpecialIndexValue('missing')
+missing = SpecialIndexValue('missing')
 
 
 class IIndexingEmptyValue(_IIndexingSpecialValue):
@@ -331,4 +342,4 @@ class IIndexingEmptyValue(_IIndexingSpecialValue):
 
 # `empty` Value can be used as query term to query
 # for objects with an empty value (like an empty set)
-empty = _SpecialIndexValue('empty')
+empty = SpecialIndexValue('empty')