prime_less_than_next_pow_2_or_1 template for unsigned types (#6)

Author: polytypic

internals/tests/testing/primes_test.cpp

@@ -2,6 +2,9 @@
 
 #include "testing_v1/test.hpp"
 
+#include <cstddef>
+#include <cstdint>
+
 using namespace testing_v1;
 
 #define VERIFY_IS_PRIME_OR_1 0
@@ -33,7 +36,23 @@ template <class T> static void test() {
   }
 }
 
+template <class T> static void test_overload() {
+  verify(127 ==
+         dumpster_v1::prime_less_than_next_pow_2_or_1(static_cast<T>(101)));
+}
+
 auto primes_test = test([]() {
   test<uint32_t>();
   test<uint64_t>();
+
+  test_overload<uint8_t>();
+  test_overload<uint16_t>();
+
+  test_overload<unsigned char>();
+  test_overload<unsigned short>();
+  test_overload<unsigned int>();
+  test_overload<unsigned long>();
+  test_overload<unsigned long long>();
+
+  test_overload<size_t>();
 });

provides/include/dumpster_v1/primes.hpp

@@ -1,3 +1,13 @@
 #pragma once
 
 #include "dumpster_v1/synopsis.hpp"
+
+template <class UnsignedType, class>
+UnsignedType dumpster_v1::prime_less_than_next_pow_2_or_1(UnsignedType x) {
+  if constexpr (sizeof(UnsignedType) <= sizeof(uint32_t))
+    return static_cast<UnsignedType>(
+        prime_less_than_next_pow_2_or_1(static_cast<uint32_t>(x)));
+  else
+    return static_cast<UnsignedType>(
+        prime_less_than_next_pow_2_or_1(static_cast<uint64_t>(x)));
+}

provides/include/dumpster_v1/synopsis.hpp

@@ -65,10 +65,17 @@ void insertion_sort(RandomIt values, Less less, IsSentinel is_sentinel);
 /// next power of 2 or 1.
 uint32_t prime_less_than_next_pow_2_or_1(uint32_t x);
 
-/// Returns the largest prime that is less than the given value rounded
-/// to the next power of 2 or 1.
+/// Returns the largest prime that is less than the given value rounded to the
+/// next power of 2 or 1.
 uint64_t prime_less_than_next_pow_2_or_1(uint64_t x);
 
+/// Returns the largest prime that is less than the given value rounded to the
+/// next power of 2 or 1.
+template <class UnsignedType,
+          class = std::enable_if_t<(std::is_unsigned_v<UnsignedType> &&
+                                    sizeof(UnsignedType) <= sizeof(uint64_t))>>
+UnsignedType prime_less_than_next_pow_2_or_1(UnsignedType x);
+
 // ranqd1.hpp ==================================================================
 
 /// The `ranqd1` generator from Numerical Recipes in C, 2nd Edition.