root: src: Random: support multiple types

Allows signed/alternative-unsigned types (impl-specific).

container/src/root/src/internal/impl/random.hh

@@ -54,6 +54,9 @@ namespace impl
 //! \since docker-finance 1.0.0
 namespace common
 {
+
+namespace type = docker_finance::internal::type;
+
 //! \brief Generic Random implementation common among all library-specific implementations
 //! \ingroup cpp_API_impl
 //! \since docker-finance 1.0.0
@@ -76,15 +79,14 @@ class RandomImpl : public ::docker_finance::internal::Random<t_impl>
   t_random generate_impl()
   {
     static_assert(
-        std::is_same_v<t_random, uint32_t>, "Random interface has changed");
+        type::is_real_integral<t_random>::value,
+        "Random interface has changed");
 
     return t_impl::that()->template generate<t_random>();
   }
 };
 }  // namespace common
 
-namespace type = docker_finance::internal::type;
-
 //! \namespace docker_finance::crypto::impl::botan
 //! \since docker-finance 1.0.0
 namespace botan
@@ -118,7 +120,13 @@ class Random : public common::RandomImpl<botan::Random>
   t_random generate_impl()
   {
     static_assert(
-        std::is_same_v<t_random, uint32_t>, "Random interface has changed");
+        type::is_real_integral<t_random>::value,
+        "Random interface has changed");
+
+    static_assert(
+        std::is_same_v<t_random, uint16_t>
+            || std::is_same_v<t_random, uint32_t>,
+        "Invalid type (only uint16_t or uint32_t supported)");
 
     THROW_IF(!m_csprng.is_seeded(), type::RuntimeError, "Botan is not seeded")
 
@@ -170,8 +178,15 @@ class Random : public common::RandomImpl<cryptopp::Random>
   template <typename t_random>
   t_random generate_impl()
   {
+    // NOTE: signed/unsigned types are supported (up to uint32_t)
     static_assert(
-        std::is_same_v<t_random, uint32_t>, "Random interface has changed");
+        type::is_real_integral<t_random>::value,
+        "Random interface has changed");
+
+    static_assert(
+        !std::is_same_v<t_random, int64_t>
+            && !std::is_same_v<t_random, uint64_t>,
+        "Invalid type (no greater than uint32_t allowed)");
 
     return m_csprng.GenerateWord32(0, std::numeric_limits<t_random>::max());
   }
@@ -226,7 +241,14 @@ class Random : public common::RandomImpl<libsodium::Random>
   t_random generate_impl()
   {
     static_assert(
-        std::is_same_v<t_random, uint32_t>, "Random interface has changed");
+        type::is_real_integral<t_random>::value,
+        "Random interface has changed");
+
+    // signed or uint64_t types are not supported
+    static_assert(
+        std::is_same_v<t_random, uint16_t>
+            || std::is_same_v<t_random, uint32_t>,
+        "Invalid type (only uint16_t or uint32_t supported)");
 
     return ::randombytes_random();
   }

container/src/root/src/random.hh

@@ -25,6 +25,7 @@
 #define CONTAINER_SRC_ROOT_SRC_RANDOM_HH_
 
 #include <cstdint>
+#include <type_traits>
 
 #include "./internal/impl/random.hh"
 
@@ -64,9 +65,17 @@ class Random final : public t_impl
 
  public:
   //! \brief Random number generator
-  //! \details Returns a random value between 0 and 0xFFFFFFFF
+  //! \details Returns a random value between 0 and 0xFFFFFFFF (depending on type)
-  //! \todo May as well enable_if uint32_t for consistency
+  //! \warning Signed types will return positive value (per implementation)
-  uint32_t generate() { return t_impl::template generate<uint32_t>(); }
+  //! \tparam t_random Integral type of random number
+  //! \return t_random Random number of type t_random
+  template <
+      typename t_random = uint32_t,
+      std::enable_if_t<type::is_real_integral<t_random>::value, bool> = true>
+  t_random generate()
+  {
+    return t_impl::template generate<t_random>();
+  }
 };
 }  // namespace common