Make narrow accept types with different signs

albin-johansson · Oct 21, 2024 · 968e13f · 968e13f
1 parent 64825dd
commit 968e13f
Show file tree

Hide file tree

Showing 2 changed files with 14 additions and 7 deletions.
diff --git a/source/base/lib/inc/tactile/base/numeric/conversion.hpp b/source/base/lib/inc/tactile/base/numeric/conversion.hpp
@@ -2,11 +2,10 @@
 
 #pragma once
 
-#include <concepts>     // integral
-#include <limits>       // numeric_limits
-#include <stdexcept>    // underflow_error, overflow_error
-#include <type_traits>  // is_signed_v
-#include <utility>      // cmp_less, cmp_greater
+#include <concepts>   // integral, same_as
+#include <limits>     // numeric_limits
+#include <stdexcept>  // underflow_error, overflow_error
+#include <utility>    // cmp_less, cmp_greater
 
 namespace tactile {
 
@@ -27,10 +26,9 @@ namespace tactile {
 template <std::integral To, std::integral From>
 [[nodiscard]] constexpr auto narrow(const From from) -> To
 {
-  static_assert(std::is_signed_v<To> == std::is_signed_v<From>);
   static_assert(sizeof(To) <= sizeof(From));
 
-  if constexpr (sizeof(To) == sizeof(From)) {
+  if constexpr (std::same_as<To, From>) {
     return static_cast<To>(from);
   }
   else {

diff --git a/source/base/test/src/numeric/conversion_test.cpp b/source/base/test/src/numeric/conversion_test.cpp
@@ -55,18 +55,27 @@ TEST(Conversion, NarrowUnsignedValues)
   EXPECT_EQ(narrow<std::uint16_t>(std::uint32_t {0xABCD}), std::uint16_t {0xABCD});
 }
 
+// tactile::narrow
+TEST(Conversion, NarrowDifferentSignValues)
+{
+  EXPECT_EQ(narrow<std::uint8_t>(std::int16_t {123}), std::uint8_t {123});
+  EXPECT_EQ(narrow<std::int16_t>(std::uint32_t {8432}), std::int16_t {8432});
+}
+
 // tactile::narrow
 TEST(Conversion, NarrowUnderflow)
 {
   EXPECT_THROW((void) narrow<std::int8_t>(std::int16_t {kMinS8} - 1), std::underflow_error);
   EXPECT_THROW((void) narrow<std::int16_t>(std::int32_t {kMinS16} - 1), std::underflow_error);
+  EXPECT_THROW((void) narrow<std::uint8_t>(std::int8_t {-1}), std::underflow_error);
 }
 
 // tactile::narrow
 TEST(Conversion, NarrowOverflow)
 {
   EXPECT_THROW((void) narrow<std::int8_t>(std::int16_t {kMaxS8} + 1), std::overflow_error);
   EXPECT_THROW((void) narrow<std::int16_t>(std::int32_t {kMaxS16} + 1), std::overflow_error);
+  EXPECT_THROW((void) narrow<std::int8_t>(std::uint8_t {129}), std::overflow_error);
 }
 
 }  // namespace