From 1c341c6888c4a3771318fcff239dd096074bec02 Mon Sep 17 00:00:00 2001
From: hashlag <hashlag@hashlag.local>
Date: Tue, 1 Sep 2026 00:43:27 +0300
Subject: [PATCH] Replace Padder CRTP base with a concept.

---
 Chaos/Padding/Padder.hpp                  | 32 ++++-------------------
 Chaos/Padding/PadderIso7816.hpp           |  4 ++-
 Chaos/Padding/PadderPkcs7.hpp             |  4 ++-
 ChaosTests/Padding/PadderIso7816Tests.cpp | 12 ++++-----
 ChaosTests/Padding/PadderPkcs7Tests.cpp   | 12 ++++-----
 5 files changed, 23 insertions(+), 41 deletions(-)

diff --git a/Chaos/Padding/Padder.hpp b/Chaos/Padding/Padder.hpp
index 5ae50e0..1807d5e 100644
--- a/Chaos/Padding/Padder.hpp
+++ b/Chaos/Padding/Padder.hpp
@@ -1,38 +1,16 @@
 #ifndef CHAOS_PADDING_PADDER_HPP
 #define CHAOS_PADDING_PADDER_HPP
 
+#include <cstdint>
+
 namespace Chaos::Padding
 {
 
 template<typename T>
-class Padder
+concept Padder = requires(uint8_t * begin, uint8_t * end)
 {
-public:
-    template<typename OutputIt>
-    void Pad(OutputIt begin, OutputIt end) const
-    {
-        Impl().Pad(begin, end);
-    }
-
-    template<typename InputIt>
-    auto ComputeUnpad(InputIt begin, InputIt end) const noexcept
-    {
-        return Impl().ComputeUnpad(begin, end);
-    }
-
-protected:
-    Padder() = default;
-
-private:
-    const T & Impl() const
-    {
-        return static_cast<const T &>(*this);
-    }
-
-    T & Impl()
-    {
-        return static_cast<T &>(*this);
-    }
+    T::Pad(begin, end);
+    { T::ComputeUnpad(begin, end) } noexcept;
 };
 
 } // namespace Chaos::Padding
diff --git a/Chaos/Padding/PadderIso7816.hpp b/Chaos/Padding/PadderIso7816.hpp
index c5af640..ee21f27 100644
--- a/Chaos/Padding/PadderIso7816.hpp
+++ b/Chaos/Padding/PadderIso7816.hpp
@@ -12,7 +12,7 @@
 namespace Chaos::Padding
 {
 
-class PadderIso7816 : public Padder<PadderIso7816>
+class PadderIso7816
 {
 public:
     template<typename OutputIt>
@@ -82,6 +82,8 @@ private:
     using Branchless = Service::Branchless;
 };
 
+static_assert(Padder<PadderIso7816>);
+
 } // namespace Chaos::Padding
 
 #endif // CHAOS_PADDING_PADDERISO7816_HPP
diff --git a/Chaos/Padding/PadderPkcs7.hpp b/Chaos/Padding/PadderPkcs7.hpp
index 325a01f..61c4a60 100644
--- a/Chaos/Padding/PadderPkcs7.hpp
+++ b/Chaos/Padding/PadderPkcs7.hpp
@@ -13,7 +13,7 @@
 namespace Chaos::Padding
 {
 
-class PadderPkcs7 : public Padder<PadderPkcs7>
+class PadderPkcs7
 {
 public:
     template<typename OutputIt>
@@ -75,6 +75,8 @@ private:
     using Branchless = Service::Branchless;
 };
 
+static_assert(Padder<PadderPkcs7>);
+
 } // namespace Chaos::Padding
 
 #endif // CHAOS_PADDING_PADDERPKCS7_HPP
diff --git a/ChaosTests/Padding/PadderIso7816Tests.cpp b/ChaosTests/Padding/PadderIso7816Tests.cpp
index 0118032..e917063 100644
--- a/ChaosTests/Padding/PadderIso7816Tests.cpp
+++ b/ChaosTests/Padding/PadderIso7816Tests.cpp
@@ -109,8 +109,8 @@ TEST(PadIso7816Tests, PadOutIteratorUsageTest)
     }
 }
 
-template<typename Impl, typename OutputIt>
-void PadThroughBase(const Padder<Impl> & padder, OutputIt begin, OutputIt end)
+template<Padder PadderImpl, typename OutputIt>
+void PadGeneric(const PadderImpl & padder, OutputIt begin, OutputIt end)
 {
     padder.Pad(begin, end);
 }
@@ -127,7 +127,7 @@ TEST(PadIso7816Tests, PadThroughBaseTest)
         };
 
         const PadderIso7816 padder;
-        PadThroughBase(padder, fact.begin(), fact.end());
+        PadGeneric(padder, fact.begin(), fact.end());
 
         ASSERT_EQ(expected, fact);
     }
@@ -324,8 +324,8 @@ TEST(PadIso7816Tests, UnpadErrorTest)
     }
 }
 
-template<typename Impl, typename OutputIt>
-auto ComputeUnpadThroughBase(const Padder<Impl> & padder, OutputIt begin, OutputIt end)
+template<Padder PadderImpl, typename OutputIt>
+auto ComputeUnpadGeneric(const PadderImpl & padder, OutputIt begin, OutputIt end)
 {
     return padder.ComputeUnpad(begin, end);
 }
@@ -336,7 +336,7 @@ TEST(PadIso7816Tests, ComputeUnpadThroughBaseTest)
         std::array<uint8_t, 5> data = { 0x80, 0x00, 0x00, 0x00, 0x00 };
 
         const PadderIso7816 padder;
-        auto result = ComputeUnpadThroughBase(padder, data.begin(), data.end());
+        auto result = ComputeUnpadGeneric(padder, data.begin(), data.end());
 
         ASSERT_TRUE(result.IsOkay_);
         ASSERT_EQ(5, result.PadSize_);
diff --git a/ChaosTests/Padding/PadderPkcs7Tests.cpp b/ChaosTests/Padding/PadderPkcs7Tests.cpp
index 112918b..57240ac 100644
--- a/ChaosTests/Padding/PadderPkcs7Tests.cpp
+++ b/ChaosTests/Padding/PadderPkcs7Tests.cpp
@@ -137,8 +137,8 @@ TEST(PadPkcs7Tests, PadOutIteratorUsageTest)
     }
 }
 
-template<typename Impl, typename OutputIt>
-void PadThroughBase(const Padder<Impl> & padder, OutputIt begin, OutputIt end)
+template<Padder PadderImpl, typename OutputIt>
+void PadGeneric(const PadderImpl & padder, OutputIt begin, OutputIt end)
 {
     padder.Pad(begin, end);
 }
@@ -153,7 +153,7 @@ TEST(PadPkcs7Tests, PadThroughBaseTest)
         };
 
         const PadderPkcs7 padder;
-        PadThroughBase(padder, fact.begin(), fact.end());
+        PadGeneric(padder, fact.begin(), fact.end());
 
         ASSERT_EQ(expected, fact);
     }
@@ -347,8 +347,8 @@ TEST(PadPkcs7Tests, UnpadErrorTest)
     }
 }
 
-template<typename Impl, typename OutputIt>
-auto ComputeUnpadThroughBase(const Padder<Impl> & padder, OutputIt begin, OutputIt end)
+template<Padder PadderImpl, typename OutputIt>
+auto ComputeUnpadGeneric(const PadderImpl & padder, OutputIt begin, OutputIt end)
 {
     return padder.ComputeUnpad(begin, end);
 }
@@ -359,7 +359,7 @@ TEST(PadPkcs7Tests, ComputeUnpadThroughBaseTest)
         std::array<uint8_t, 5> data = { 0x05, 0x05, 0x05, 0x05, 0x05 };
 
         const PadderPkcs7 padder;
-        auto result = ComputeUnpadThroughBase(padder, data.begin(), data.end());
+        auto result = ComputeUnpadGeneric(padder, data.begin(), data.end());
 
         ASSERT_TRUE(result.IsOkay_);
         ASSERT_EQ(5, result.PadSize_);