Skip unversioned for adjacent mutations, reverse reads

Facade.h

@@ -53,12 +53,13 @@ struct Facade {
         do {
           --iter;
           auto m = *iter;
-          const auto mBegin =
+          auto mBegin = weaselab::VersionedMap::Key{m.param1, m.param1Len};
-              weaselab::VersionedMap::Key{m.param1, m.param1Len};
+          auto mEnd =
-          const auto mEnd =
               m.type == weaselab::VersionedMap::Set || m.param2Len == 0
                   ? weaselab::VersionedMap::Key{m.param1, m.param1Len + 1}
                   : weaselab::VersionedMap::Key{m.param2, m.param2Len};
+
+          // Read from unversioned down to mEnd
           if (unversionedIter != beginIter) {
             --unversionedIter;
             for (; unversionedIter->first >= mEnd && limit > 0;
@@ -73,6 +74,12 @@ struct Facade {
           if (limit == 0) {
             return result;
           }
+
+          bool pointMutation =
+              m.type == weaselab::VersionedMap::Set || m.param2Len == 0;
+
+          // Read from versioned until non-adjacent
+        readVersionedReverse:
           switch (m.type) {
           case weaselab::VersionedMap::Set: {
             result.emplace_back(String(mBegin.p, mBegin.len),
@@ -85,7 +92,31 @@ struct Facade {
           case weaselab::VersionedMap::Clear:
             break;
           }
-          if (m.type == weaselab::VersionedMap::Set || m.param2Len == 0) {
+
+          if (iter != endIter) {
+            --iter;
+            auto tmpM = *iter;
+            const auto tmpMBegin =
+                weaselab::VersionedMap::Key{tmpM.param1, tmpM.param1Len};
+            const auto tmpMEnd =
+                tmpM.type == weaselab::VersionedMap::Set || tmpM.param2Len == 0
+                    ? weaselab::VersionedMap::Key{tmpM.param1,
+                                                  tmpM.param1Len + 1}
+                    : weaselab::VersionedMap::Key{tmpM.param2, tmpM.param2Len};
+            if (tmpMEnd >= mBegin) {
+              // Adjacent with last (temporally) mutation
+              mBegin = tmpMBegin;
+              mEnd = tmpMEnd;
+              m = tmpM;
+              pointMutation = false;
+              goto readVersionedReverse;
+            } else {
+              ++iter;
+            }
+          }
+
+          // Advance unversioned iter
+          if (pointMutation) {
             if (unversionedIter != facade->unversioned.end() &&
                 unversionedIter->first < mBegin) {
               ++unversionedIter;
@@ -135,7 +166,7 @@ struct Facade {
               m.type == weaselab::VersionedMap::Set || m.param2Len == 0;
 
           // Read from versioned until non-adjacent
-        readVersioned:
+        readVersionedForward:
           switch (m.type) {
           case weaselab::VersionedMap::Set: {
             result.emplace_back(String(mBegin.p, mBegin.len),
@@ -163,7 +194,7 @@ struct Facade {
                                                        tmpM.param2Len};
               m = tmpM;
               pointMutation = false;
-              goto readVersioned;
+              goto readVersionedForward;
             }
           }