Add Entry::pointClear

VersionedMap.cpp

@@ -91,6 +91,7 @@ struct Entry {
   // True if the entry is a point mutation. If false, this entry's key should be
   // read through to the underlying data structure.
   bool pointMutation() const { return pointVersion >= 0; }
+  bool pointClear() const { return pointVersion >= 0 && valLen < 0; }
 
   // True if mutations in (pred, this) are cleared. If false, (pred, this)
   // should be read through to the underlying data structure.
@@ -1065,8 +1066,7 @@ void materializeMutations(VersionedMap::Iterator::Impl *impl, const Entry *prev,
     impl->mutations[impl->mutationCount++] = {
         prev->getKey(),
         entry.getKey(),
-        prev->pointMutation() && prev->valLen < 0 &&
-                prev->pointVersion == entry.rangeVersion
+        prev->pointClear() && prev->pointVersion == entry.rangeVersion
             ? prev->keyLen
             : prev->keyLen + 1,
         entry.keyLen,
@@ -1074,7 +1074,7 @@ void materializeMutations(VersionedMap::Iterator::Impl *impl, const Entry *prev,
         entry.rangeVersion};
   }
   if (entry.pointMutation()) {
-    if (entry.valLen < 0) {
+    if (entry.valLen < 0 /* pointClear */) {
       if (next == nullptr ||
           !(next->clearTo() && next->rangeVersion == entry.pointVersion)) {
         impl->mutations[impl->mutationCount++] = {