Safeguard: No scalar and vector components side by side

"A scalar component can not be contained at the same time as one or more regular components."

Author: franzpoeschel

include/openPMD/RecordComponent.hpp

@@ -154,7 +154,7 @@ class RecordComponent : public BaseRecordComponent
      *
      * @return RecordComponent&
      */
-    RecordComponent &resetDataset(Dataset);
+    virtual RecordComponent &resetDataset(Dataset);
 
     uint8_t getDimensionality() const;
     Extent getExtent() const;

include/openPMD/backend/BaseRecord.hpp

@@ -20,9 +20,11 @@
  */
 #pragma once
 
+#include "openPMD/Error.hpp"
 #include "openPMD/RecordComponent.hpp"
 #include "openPMD/UnitDimension.hpp"
 #include "openPMD/auxiliary/Variant.hpp"
+#include "openPMD/backend/BaseRecordComponent.hpp"
 #include "openPMD/backend/Container.hpp"
 
 #include <array>
@@ -454,6 +456,17 @@ class BaseRecord
      */
     std::array<double, 7> unitDimension() const;
 
+    void setDatasetDefined(BaseRecordComponent::Data_t &data) override
+    {
+        if (!T_Container::empty())
+        {
+            throw error::WrongAPIUsage(
+                "A scalar component can not be contained at the same time as "
+                "one or more regular components.");
+        }
+        T_RecordComponent::setDatasetDefined(data);
+    }
+
     /** Returns true if this record only contains a single component
      *
      * @return true if a record with only a single component
@@ -528,9 +541,9 @@ auto BaseRecord<T_elem>::operator[](key_type const &key) -> mapped_type &
         bool const keyScalar = (key == RecordComponent::SCALAR);
         if ((keyScalar && !Container<T_elem>::empty() && !scalar()) ||
             (scalar() && !keyScalar))
-            throw std::runtime_error(
-                "A scalar component can not be contained at "
-                "the same time as one or more regular components.");
+            throw error::WrongAPIUsage(
+                "A scalar component can not be contained at the same time as "
+                "one or more regular components.");
 
         if (keyScalar)
         {
@@ -570,9 +583,9 @@ auto BaseRecord<T_elem>::operator[](key_type &&key) -> mapped_type &
         bool const keyScalar = (key == RecordComponent::SCALAR);
         if ((keyScalar && !Container<T_elem>::empty() && !scalar()) ||
             (scalar() && !keyScalar))
-            throw std::runtime_error(
-                "A scalar component can not be contained at "
-                "the same time as one or more regular components.");
+            throw error::WrongAPIUsage(
+                "A scalar component can not be contained at the same time as "
+                "one or more regular components.");
 
         if (keyScalar)
         {
@@ -961,6 +974,17 @@ inline void BaseRecord<T_elem>::flush(
             "RecordComponents: " +
             name);
 
+    /*
+     * Defensive programming. Normally, this error should yield as soon as
+     * possible.
+     */
+    if (scalar() && !T_Container::empty())
+    {
+        throw error::WrongAPIUsage(
+            "A scalar component can not be contained at the same time as "
+            "one or more regular components.");
+    }
+
     this->flush_impl(name, flushParams);
     // flush_impl must take care to correctly set the dirty() flag so this
     // method doesn't do it

include/openPMD/backend/BaseRecordComponent.hpp

@@ -179,7 +179,7 @@ class BaseRecordComponent : virtual public Attributable
         Attributable::setData(m_baseRecordComponentData);
     }
 
-    void setDatasetDefined(Data_t &);
+    virtual void setDatasetDefined(Data_t &);
 
     bool datasetDefined() const;
 

include/openPMD/backend/PatchRecordComponent.hpp

@@ -86,7 +86,7 @@ class PatchRecordComponent : public BaseRecordComponent
 public:
     PatchRecordComponent &setUnitSI(double);
 
-    PatchRecordComponent &resetDataset(Dataset);
+    virtual PatchRecordComponent &resetDataset(Dataset);
 
     uint8_t getDimensionality() const;
     Extent getExtent() const;

test/CoreTest.cpp

@@ -1,4 +1,6 @@
 // expose private and protected members for invasive testing
+#include "openPMD/Datatype.hpp"
+#include "openPMD/Error.hpp"
 #if openPMD_USE_INVASIVE_TESTS
 #define OPENPMD_private public:
 #define OPENPMD_protected public:
@@ -1379,3 +1381,44 @@ TEST_CASE("unique_ptr", "[core]")
     UniquePtrWithLambda<int[]> arrptrFilledCustom{
         new int[5]{}, [](int const *p) { delete[] p; }};
 }
+
+TEST_CASE("scalar_and_vector", "[core]")
+{
+    {
+        Series series("../samples/scalar_and_vector.json", Access::CREATE);
+        auto E = series.iterations[0].meshes["E"];
+        E["x"].makeEmpty(Datatype::FLOAT, 3);
+        REQUIRE_THROWS_AS(
+            E.makeEmpty(Datatype::FLOAT, 3), error::WrongAPIUsage);
+    }
+    {
+        Series series("scalar_and_vector.json", Access::CREATE);
+        auto E = series.iterations[0].meshes["E"];
+        E.makeEmpty(Datatype::FLOAT, 3);
+        REQUIRE_THROWS_AS(E["x"], error::WrongAPIUsage);
+    }
+    {
+        Series series("../samples/scalar_and_vector.json", Access::CREATE);
+        auto E = series.iterations[0].meshes["E"];
+        E["x"].makeEmpty(Datatype::FLOAT, 3);
+    }
+    {
+        Series read("../samples/scalar_and_vector.json", Access::READ_ONLY);
+        auto E = read.iterations[0].meshes["E"];
+        REQUIRE(E.size() == 1);
+        REQUIRE(!E.scalar());
+        REQUIRE(E.contains("x"));
+    }
+    {
+        Series series("../samples/scalar_and_vector.json", Access::CREATE);
+        auto E = series.iterations[0].meshes["E"];
+        E.makeEmpty(Datatype::FLOAT, 3);
+    }
+    {
+        Series read("../samples/scalar_and_vector.json", Access::READ_ONLY);
+        auto E = read.iterations[0].meshes["E"];
+        REQUIRE(E.size() == 1);
+        REQUIRE(E.scalar());
+        REQUIRE(!E.contains("x"));
+    }
+}