Fix type label deduction in VTKWriter

fix #15

src/output/VTKWriter.hpp

@@ -85,6 +85,19 @@ class VTKWriter
   template <typename DataType>
   struct VTKType
   {
+    inline const static std::string name = [] {
+      static_assert(std::is_arithmetic_v<DataType>, "invalid data type");
+
+      if constexpr (std::is_integral_v<DataType>) {
+        if constexpr (std::is_unsigned_v<DataType>) {
+          return "UInt" + std::to_string(sizeof(DataType) * 8);
+        } else {
+          return "UInt" + std::to_string(sizeof(DataType) * 8);
+        }
+      } else if constexpr (std::is_floating_point_v<DataType>) {
+        return "Float" + std::to_string(sizeof(DataType) * 8);
+      }
+    }();
   };
 
   template <typename DataType>
@@ -360,64 +373,4 @@ class VTKWriter
   ~VTKWriter() = default;
 };
 
-template <>
-struct VTKWriter::VTKType<int8_t>
-{
-  inline const static std::string name{"Int8"};
-};
-
-template <>
-struct VTKWriter::VTKType<uint8_t>
-{
-  inline const static std::string name{"UInt8"};
-};
-
-template <>
-struct VTKWriter::VTKType<int16_t>
-{
-  inline const static std::string name{"Int16"};
-};
-
-template <>
-struct VTKWriter::VTKType<uint16_t>
-{
-  inline const static std::string name{"UInt16"};
-};
-
-template <>
-struct VTKWriter::VTKType<int32_t>
-{
-  inline const static std::string name{"Int32"};
-};
-
-template <>
-struct VTKWriter::VTKType<uint32_t>
-{
-  inline const static std::string name{"UInt32"};
-};
-
-template <>
-struct VTKWriter::VTKType<int64_t>
-{
-  inline const static std::string name{"Int64"};
-};
-
-template <>
-struct VTKWriter::VTKType<uint64_t>
-{
-  inline const static std::string name{"UInt64"};
-};
-
-template <>
-struct VTKWriter::VTKType<float>
-{
-  inline const static std::string name{"Float32"};
-};
-
-template <>
-struct VTKWriter::VTKType<double>
-{
-  inline const static std::string name{"Float64"};
-};
-
 #endif   // VTK_WRITER_HPP