addressing comments regarding the FastSmallVector::expandSize

it is renamed to a more general resize and the function is revised
accordingly.

Author: GitPaean

opm/material/common/FastSmallVector.hpp

@@ -198,17 +198,23 @@ class FastSmallVector
         }
     }
 
-    void expandSize(size_t numElem)
+    void resize(size_t numElem)
     {
-        assert(numElem >= size_);
-        if (size_ <= N) {
+        if (numElem == size_) return; // nothing to do
+
+        if (dataPtr_ == smallBuf_.data()) {
             if (numElem > N) {
-                data_.resize(numElem, 0);
-                data_.assign(smallBuf_.begin(), smallBuf_.begin() + size_);
+                data_.resize(numElem);
+                std::copy(smallBuf_.begin(), smallBuf_.begin() + size_, data_.begin());
                 dataPtr_ = data_.data();
+            } else if (numElem < size_) {
+                // when shrinking, remove the values after numElem so that the space
+                // is ready to use in the potentional future resize
+                std::fill(smallBuf_.begin() + numElem, smallBuf_.begin() + size_, ValueType{});
             }
         } else {
-            data_.resize(numElem, 0);
+            // when shriking to numElem < N, we do not switch back to use smallBuf_
+            data_.resize(numElem);
         }
         size_ = numElem;
     }

opm/material/densead/DynamicEvaluation.hpp

@@ -691,7 +691,7 @@ class Evaluation<ValueT, DynamicSize, staticSize>
     void appendDerivativesToConstant(size_t numDer) {
         assert(size() == 0); // we only append derivatives to a constant
         if (numDer > 0) {
-            data_.expandSize(1 + numDer);
+            data_.resize(1 + numDer);
         }
     }
 };