Enable empty string attributes (#1338)

* Enable empty string attributes

* Disable empty strings exclusively for ADIOS1

Author: franzpoeschel

include/openPMD/backend/Attributable.hpp

@@ -81,39 +81,6 @@ namespace internal
         A_MAP m_attributes;
     };
 
-    enum class SetAttributeMode : char
-    {
-        WhileReadingAttributes,
-        FromPublicAPICall
-    };
-
-    /** Verify values of attributes in the frontend
-     *
-     * verify string attributes are not empty (backend restriction, e.g., HDF5)
-     */
-    template <typename T>
-    inline void attr_value_check(
-        std::string const /* key */, T /* value */, SetAttributeMode)
-    {}
-
-    template <>
-    inline void attr_value_check(
-        std::string const key, std::string const value, SetAttributeMode mode)
-    {
-        switch (mode)
-        {
-        case SetAttributeMode::FromPublicAPICall:
-            if (value.empty())
-                throw std::runtime_error(
-                    "[setAttribute] Value for string attribute '" + key +
-                    "' must not be empty!");
-            break;
-        case SetAttributeMode::WhileReadingAttributes:
-            // no checks while reading
-            break;
-        }
-    }
-
     template <typename>
     class BaseRecordData;
 } // namespace internal
@@ -289,12 +256,6 @@ OPENPMD_protected
 
     void flushAttributes(internal::FlushParams const &);
 
-    template <typename T>
-    bool setAttributeImpl(
-        std::string const &key, T value, internal::SetAttributeMode);
-    bool setAttributeImpl(
-        std::string const &key, char const value[], internal::SetAttributeMode);
-
     enum ReadMode
     {
         /**
@@ -435,30 +396,11 @@ OPENPMD_protected
     virtual void linkHierarchy(Writable &w);
 }; // Attributable
 
-template <typename T>
-inline bool Attributable::setAttribute(std::string const &key, T value)
-{
-    return setAttributeImpl(
-        key, std::move(value), internal::SetAttributeMode::FromPublicAPICall);
-}
-
-inline bool
-Attributable::setAttribute(std::string const &key, char const value[])
-{
-    return setAttributeImpl(
-        key, value, internal::SetAttributeMode::FromPublicAPICall);
-}
-
 // note: we explicitly instantiate Attributable::setAttributeImpl for all T in
 // Datatype in Attributable.cpp
 template <typename T>
-inline bool Attributable::setAttributeImpl(
-    std::string const &key,
-    T value,
-    internal::SetAttributeMode setAttributeMode)
+inline bool Attributable::setAttribute(std::string const &key, T value)
 {
-    internal::attr_value_check(key, value, setAttributeMode);
-
     auto &attri = get();
     if (IOHandler() &&
         IOHandler()->m_seriesStatus == internal::SeriesStatus::Default &&
@@ -487,12 +429,10 @@ inline bool Attributable::setAttributeImpl(
     }
 }
 
-inline bool Attributable::setAttributeImpl(
-    std::string const &key,
-    char const value[],
-    internal::SetAttributeMode setAttributeMode)
+inline bool
+Attributable::setAttribute(std::string const &key, char const value[])
 {
-    return this->setAttributeImpl(key, std::string(value), setAttributeMode);
+    return this->setAttribute(key, std::string(value));
 }
 
 template <typename T>

src/IO/ADIOS/CommonADIOS1IOHandler.cpp

@@ -235,6 +235,11 @@ void CommonADIOS1IOHandlerImpl<ChildClass>::flush_attribute(
     }
     case DT::STRING: {
         auto const &v = att.get<std::string>();
+        if (v.empty())
+        {
+            error::throwOperationUnsupportedInBackend(
+                "ADIOS1", "Empty string attributes not supported.");
+        }
         values = auxiliary::allocatePtr(Datatype::CHAR, v.length() + 1u);
         strcpy((char *)values.get(), v.c_str());
         break;
@@ -352,6 +357,11 @@ void CommonADIOS1IOHandlerImpl<ChildClass>::flush_attribute(
         auto const &vec = att.get<std::vector<std::string> >();
         for (size_t i = 0; i < vec.size(); ++i)
         {
+            if (vec[i].empty())
+            {
+                error::throwOperationUnsupportedInBackend(
+                    "ADIOS1", "Empty string attributes not supported.");
+            }
             size_t size = vec[i].size() + 1;
             ptr[i] = new char[size];
             strncpy(ptr[i], vec[i].c_str(), size);

src/IO/HDF5/HDF5Auxiliary.cpp

@@ -111,8 +111,7 @@ hid_t openPMD::GetH5DataType::operator()(Attribute const &att)
             m_userTypes.at(typeid(std::complex<long double>).name()));
     case DT::STRING: {
         hid_t string_t_id = H5Tcopy(H5T_C_S1);
-        size_t const max_len = att.get<std::string>().size();
-        VERIFY(max_len > 0, "[HDF5] max_len must be >0 for STRING");
+        size_t const max_len = att.get<std::string>().size() + 1;
         herr_t status = H5Tset_size(string_t_id, max_len);
         VERIFY(
             status >= 0,
@@ -123,7 +122,7 @@ hid_t openPMD::GetH5DataType::operator()(Attribute const &att)
         hid_t string_t_id = H5Tcopy(H5T_C_S1);
         size_t max_len = 0;
         for (std::string const &s : att.get<std::vector<std::string> >())
-            max_len = std::max(max_len, s.size());
+            max_len = std::max(max_len, s.size() + 1);
         VERIFY(max_len > 0, "[HDF5] max_len must be >0 for VEC_STRING");
         herr_t status = H5Tset_size(string_t_id, max_len);
         VERIFY(

src/IO/HDF5/HDF5IOHandler.cpp

@@ -1621,8 +1621,8 @@ void HDF5IOHandlerImpl::writeAttribute(
         auto vs = att.get<std::vector<std::string> >();
         size_t max_len = 0;
         for (std::string const &s : vs)
-            max_len = std::max(max_len, s.size());
-        std::unique_ptr<char[]> c_str(new char[max_len * vs.size()]);
+            max_len = std::max(max_len, s.size() + 1);
+        std::unique_ptr<char[]> c_str(new char[max_len * vs.size()]());
         for (size_t i = 0; i < vs.size(); ++i)
             strncpy(c_str.get() + i * max_len, vs[i].c_str(), max_len);
         status = H5Awrite(attribute_id, dataType, c_str.get());