Add Padder<>. A CRTP base for padding algorithms.

Chaos/Padding/Padder.hpp

@@ -0,0 +1,34 @@
+#ifndef CHAOS_PADDING_PADDER_HPP
+#define CHAOS_PADDING_PADDER_HPP
+
+namespace Chaos::Padding
+{
+
+template<typename T>
+class Padder
+{
+public:
+    template<typename OutputIt>
+    void Pad(OutputIt begin, OutputIt end) const
+    {
+        Impl().Pad(begin, end);
+    }
+
+protected:
+    Padder() = default;
+
+private:
+    const T & Impl() const
+    {
+        return static_cast<const T &>(*this);
+    }
+
+    T & Impl()
+    {
+        return static_cast<T &>(*this);
+    }
+};
+
+} // namespace Chaos::Padding
+
+#endif // CHAOS_PADDING_PADDER_HPP

Chaos/Padding/PadderPkcs7.hpp

@@ -5,12 +5,13 @@
 #include <iterator>
 #include <limits>
 
+#include "Padding/Padder.hpp"
 #include "Service/ChaosException.hpp"
 
 namespace Chaos::Padding
 {
 
-class PadderPkcs7
+class PadderPkcs7 : public Padder<PadderPkcs7>
 {
 public:
     template<typename OutputIt>