Added ensure() utility to throw an exception if a condition isn't fulfilled.

source/mijin/util/exception.hpp

@@ -0,0 +1,30 @@
+
+#pragma once
+
+#ifndef MIJIN_UTIL_EXCEPTION_HPP_INCLUDED
+#define MIJIN_UTIL_EXCEPTION_HPP_INCLUDED 1
+
+#include <stdexcept>
+
+namespace mijin
+{
+
+//
+// public defines
+//
+
+//
+// public functions
+//
+
+template<typename TCondition, typename TException = std::runtime_error, typename... TExceptionArgs>
+inline decltype(auto) ensure(TCondition&& condition, TExceptionArgs&&... args)
+{
+    if (!static_cast<bool>(std::forward<TCondition>(condition)))
+    {
+        throw TException(std::forward<TExceptionArgs>(args)...);
+    }
+    return std::forward<TCondition>(condition);
+}
+} // namespace mijin
+#endif // MIJIN_UTIL_EXCEPTION_HPP_INCLUDED