From 4b8ab3eeda06f7779c6ee71e36bfa70a517d42a0 Mon Sep 17 00:00:00 2001
From: John Wellbelove <john.wellbelove@etlcpp.com>
Date: Mon, 13 Oct 2025 23:02:45 +0100
Subject: [PATCH] Added type_list_has_duplicates_of and type_list_count_of

---
 include/etl/type_list.h | 46 +++++++++++++++++++++++++++++++++++
 test/test_type_list.cpp | 54 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 100 insertions(+)

diff --git a/include/etl/type_list.h b/include/etl/type_list.h
index 2042ff79..eeea5052 100644
--- a/include/etl/type_list.h
+++ b/include/etl/type_list.h
@@ -205,6 +205,52 @@ namespace etl
   inline constexpr bool type_list_contains_v = etl::type_list_contains<TTypeList, T>::value;
 #endif
 
+  //***************************************************************************
+  /// Defines a bool constant that is true if the type_list has duplicates of the specified type, otherwise false.
+  //***************************************************************************
+  template <typename T, typename TTypes>
+  struct type_list_has_duplicates_of;
+
+  template <typename T, typename... TTypes>
+  struct type_list_has_duplicates_of<etl::type_list<TTypes...>, T>
+    : public etl::has_duplicates_of<T, TTypes...>
+  {
+  };
+
+  template <typename T>
+  struct type_list_has_duplicates_of<type_list<>, T>
+    : public etl::integral_constant<bool, false>
+  {
+  };
+
+#if ETL_USING_CPP17
+  template <typename TTypeList, typename T>
+  inline constexpr bool type_list_has_duplicates_of_v = etl::type_list_has_duplicates_of<TTypeList, T>::value;
+#endif
+
+  //***************************************************************************
+  /// Defines an integral constant that is the count of the number of times a type is in the type list.
+  //***************************************************************************
+  template <typename T, typename TTypes>
+  struct type_list_count_of;
+
+  template <typename T, typename... TTypes>
+  struct type_list_count_of<etl::type_list<TTypes...>, T>
+    : public etl::count_of<T, TTypes...>
+  {
+  };
+
+  template <typename T>
+  struct type_list_count_of<type_list<>, T>
+    : public etl::integral_constant<size_t, 0>
+  {
+  };
+
+#if ETL_USING_CPP17
+  template <typename TTypeList, typename T>
+  inline constexpr size_t type_list_count_of_v = etl::type_list_count_of<TTypeList, T>::value;
+#endif
+
   //***************************************************************************
   /// Defines an integral constant that is maximum sizeof all types in the type_list.
   /// If the type_list is empty, then defined as 0.
diff --git a/test/test_type_list.cpp b/test/test_type_list.cpp
index 5cd253d0..df37af51 100644
--- a/test/test_type_list.cpp
+++ b/test/test_type_list.cpp
@@ -105,6 +105,60 @@ namespace
 #endif
     }
 
+    //*************************************************************************
+    TEST(test_type_list_has_duplicates_of)
+    {
+      typedef etl::type_list<char, int, uint32_t> t1;
+      typedef etl::type_list<uint8_t, uint16_t, uint8_t>   t2;
+      typedef etl::type_list<uint16_t> t3;
+      typedef etl::type_list<> t4;
+
+      CHECK_FALSE((etl::type_list_has_duplicates_of<t1,  char>::value));
+      CHECK_FALSE((etl::type_list_has_duplicates_of<t1, uint8_t>::value));
+      CHECK_FALSE((etl::type_list_has_duplicates_of<t2, int>::value));
+      CHECK_TRUE((etl::type_list_has_duplicates_of<t2,  uint8_t>::value));
+      CHECK_FALSE((etl::type_list_has_duplicates_of<t3,  uint16_t>::value));
+      CHECK_FALSE((etl::type_list_has_duplicates_of<t3, uint32_t>::value));
+      CHECK_FALSE((etl::type_list_has_duplicates_of<t4, uint32_t>::value));
+
+#if ETL_USING_CPP17
+      CHECK_FALSE((etl::type_list_has_duplicates_of_v<t1,  char>));
+      CHECK_FALSE((etl::type_list_has_duplicates_of_v<t1, uint8_t>));
+      CHECK_FALSE((etl::type_list_has_duplicates_of_v<t2, int>));
+      CHECK_TRUE((etl::type_list_has_duplicates_of_v<t2,  uint8_t>));
+      CHECK_FALSE((etl::type_list_has_duplicates_of_v<t3,  uint16_t>));
+      CHECK_FALSE((etl::type_list_has_duplicates_of_v<t3, uint32_t>));
+      CHECK_FALSE((etl::type_list_has_duplicates_of_v<t4, uint32_t>));
+#endif
+    }
+
+    //*************************************************************************
+    TEST(test_type_list_count_of)
+    {
+      typedef etl::type_list<char, int, uint32_t> t1;
+      typedef etl::type_list<uint8_t, uint16_t, uint8_t>   t2;
+      typedef etl::type_list<uint16_t> t3;
+      typedef etl::type_list<> t4;
+
+      CHECK_EQUAL(1, (etl::type_list_count_of<t1,  char>::value));
+      CHECK_EQUAL(0, (etl::type_list_count_of<t1, uint8_t>::value));
+      CHECK_EQUAL(0, (etl::type_list_count_of<t2, int>::value));
+      CHECK_EQUAL(2, (etl::type_list_count_of<t2,  uint8_t>::value));
+      CHECK_EQUAL(1, (etl::type_list_count_of<t3,  uint16_t>::value));
+      CHECK_EQUAL(0, (etl::type_list_count_of<t3, uint32_t>::value));
+      CHECK_EQUAL(0, (etl::type_list_count_of<t4, uint32_t>::value));
+
+#if ETL_USING_CPP17
+      CHECK_EQUAL(1, (etl::type_list_count_of_v<t1,  char>));
+      CHECK_EQUAL(0, (etl::type_list_count_of_v<t1, uint8_t>));
+      CHECK_EQUAL(0, (etl::type_list_count_of_v<t2, int>));
+      CHECK_EQUAL(2, (etl::type_list_count_of_v<t2,  uint8_t>));
+      CHECK_EQUAL(1, (etl::type_list_count_of_v<t3,  uint16_t>));
+      CHECK_EQUAL(0, (etl::type_list_count_of_v<t3, uint32_t>));
+      CHECK_EQUAL(0, (etl::type_list_count_of_v<t4, uint32_t>));
+#endif
+    }
+
     //*************************************************************************
     TEST(test_type_list_index_of_type)
     {