Added function field_operation()

src/Diff.cc

@@ -124,13 +124,24 @@ diff(size_t n, const Field &field1, const Field &field2)
   return diffParam;
 }
 
-static void
-use_real_part(size_t gridsize, Field &field)
+template <typename FUNC, typename FIELD, typename... ARGS>
+inline auto
+field_operation(FUNC func, FIELD &field, ARGS &...args) -> decltype(func(field.vec_f, args...))
 {
   if (field.memType == MemType::Float)
-    for (size_t i = 0; i < gridsize; ++i) field.vec_f[i] = field.vec_f[i * 2];
+    return func(field.vec_f, args...);
   else
-    for (size_t i = 0; i < gridsize; ++i) field.vec_d[i] = field.vec_d[i * 2];
+    return func(field.vec_d, args...);
+}
+
+static void
+use_real_part(Field &field)
+{
+  auto func = [](auto &v) {
+    auto n = v.size() / 2;
+    for (size_t i = 0; i < n; ++i) v[i] = v[i * 2];
+  };
+  return field_operation(func, field);
 }
 
 struct DiffParam
@@ -385,11 +396,11 @@ public:
 
             field1.init(var1);
             cdo_read_record(streamID1, field1);
-            if (var1.nwpv == CDI_COMP) use_real_part(var1.gridsize, field1);
+            if (var1.nwpv == CDI_COMP) use_real_part(field1);
 
             field2.init(var2);
             cdo_read_record(streamID2, field2);
-            if (var2.nwpv == CDI_COMP) use_real_part(var1.gridsize, field2);
+            if (var2.nwpv == CDI_COMP) use_real_part(field2);
 
             if (runAsync && numSets > 0)
               {