update type name rtti

doc/reference.md

@@ -12,6 +12,7 @@
 * [`NAMEOF_FULL_TYPE` macro that obtains string name of full type, with reference and cv-qualifiers.](#nameof_full_type-1)
 * [`NAMEOF_TYPE_EXPR` macro that obtains string name type of expression, reference and cv-qualifiers are ignored.](#nameof_type_expr)
 * [`NAMEOF_FULL_TYPE_EXPR` macro that obtains string name full type of expression, with reference and cv-qualifiers.](#nameof_full_type_expr)
+* [`NAMEOF_TYPE_RTTI` macro that obtains string name type, using RTTI.](#nameof_type_rtti)
 
 ## Synopsis
 
@@ -256,3 +257,20 @@
   T var = 42;
   NAMEOF_FULL_TYPE_EXPR(var) -> "const int&"
   ```
+
+## `NAMEOF_TYPE_RTTI`
+
+* Macro macro that obtains string name of type, using RTTI.
+
+* Returns demangled RTTI type name.
+
+* Examples
+
+  ```cpp
+  struct Base { virtual void foo() {} };
+  struct Derived : Base {};
+
+  Base* ptr = new Derived();
+  NAMEOF_TYPE_RTTI(ptr)  -> "Base *"
+  NAMEOF_TYPE_RTTI(*ptr) -> "Derived"
+  ```

example/example.cpp

@@ -27,6 +27,10 @@
 #include <sstream>
 #include <stdexcept>
 
+struct Base { virtual void foo() {} };
+
+struct Derived : Base {};
+
 struct SomeStruct {
   int somefield = 0;
 
@@ -161,6 +165,13 @@ int main() {
   std::cout << NAMEOF_RAW(structvar.somefield) << std::endl; // 'structvar.somefield'
   std::cout << NAMEOF_RAW(&SomeStruct::SomeMethod1) << std::endl; // '&SomeStruct::SomeMethod1'
 
+#if defined(NAMEOF_TYPE_RTTI_SUPPORTED)
+  // Nameof type using RTTI.
+  Base* ptr = new Derived();
+  std::cout << NAMEOF_TYPE_RTTI(ptr) << std::endl; // "Base *"
+  std::cout << NAMEOF_TYPE_RTTI(*ptr) << std::endl; // "Derived"
+#endif
+
   // Some more complex example.
 
   std::cout << SomeMethod4<int>(structvar) << std::endl; // 'SomeMethod4<int, SomeStruct>(SomeStruct value)'

include/nameof.hpp

@@ -568,14 +568,18 @@ inline constexpr auto type_name_v = n<T...>();
 
 #if __has_include(<cxxabi.h>)
 inline std::string demangle(const char* tn) {
+  if (tn == nullptr) {
+    return {};
+  }
+
   auto dmg = abi::__cxa_demangle(tn, nullptr, nullptr, nullptr);
   auto r = std::string{dmg != nullptr ? dmg : tn};
   std::free(dmg);
   return r;
 }
 #else
 constexpr std::string_view demangle(const char* tn) noexcept {
-  return std::string_view{tn};
+  return {tn};
 }
 #endif
 
@@ -699,7 +703,7 @@ template <typename T>
 // Obtains string name full type of expression, with reference and cv-qualifiers.
 #define NAMEOF_FULL_TYPE_EXPR(...) ::nameof::nameof_full_type<decltype(__VA_ARGS__)>()
 
-// Obtains string name of type using RTTI.
+// Obtains string name of type, using RTTI.
 #define NAMEOF_TYPE_RTTI(...) ::nameof::detail::demangle(typeid(__VA_ARGS__).name())
 
 #if defined(_MSC_VER)