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memory: turn is_power_of_two in a constexpr function

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This commit is contained in:
Michele Caini
2021-08-31 17:39:47 +02:00
parent f7d67067ad
commit 5ddc746915
2 changed files with 14 additions and 20 deletions
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20
src/entt/core/memory.hpp
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@@ -74,19 +74,13 @@ constexpr void propagate_on_container_swap(Allocator &lhs, Allocator &rhs) ENTT_
/**
* @brief Utility class to check whether a value is a power of two or not.
* @tparam Value A value that may or may not be a power of two.
* @brief Checks whether a value is a power of two or not.
* @param value A value that may or may not be a power of two.
* @return True if the value is a power of two, false otherwise.
*/
template<std::size_t Value>
using is_power_of_two = std::bool_constant<Value && ((Value & (Value - 1)) == 0)>;
/**
* @brief Helper variable template.
* @tparam Value A value that may or may not be a power of two.
*/
template<std::size_t Value>
inline constexpr bool is_power_of_two_v = is_power_of_two<Value>::value;
[[nodiscard]] inline constexpr bool is_power_of_two(const std::size_t value) ENTT_NOEXCEPT {
return value && ((value & (value - 1)) == 0);
}
/**
@@ -97,7 +91,7 @@ inline constexpr bool is_power_of_two_v = is_power_of_two<Value>::value;
*/
template<std::size_t Value>
[[nodiscard]] constexpr std::size_t fast_mod(const std::size_t value) ENTT_NOEXCEPT {
static_assert(is_power_of_two_v<Value>, "Value must be a power of two");
static_assert(is_power_of_two(Value), "Value must be a power of two");
return value & (Value - 1u);
}

14
test/entt/core/memory.cpp
View File

@@ -33,13 +33,13 @@ TEST(Memory, PoccaPocmaAndPocs) {
}
TEST(Memory, IsPowerOfTwo) {
ASSERT_FALSE(entt::is_power_of_two_v<0u>);
ASSERT_TRUE(entt::is_power_of_two_v<1u>);
ASSERT_TRUE(entt::is_power_of_two_v<2u>);
ASSERT_TRUE(entt::is_power_of_two_v<4u>);
ASSERT_FALSE(entt::is_power_of_two_v<7u>);
ASSERT_TRUE(entt::is_power_of_two_v<128u>);
ASSERT_FALSE(entt::is_power_of_two_v<200u>);
ASSERT_FALSE(entt::is_power_of_two(0u));
ASSERT_TRUE(entt::is_power_of_two(1u));
ASSERT_TRUE(entt::is_power_of_two(2u));
ASSERT_TRUE(entt::is_power_of_two(4u));
ASSERT_FALSE(entt::is_power_of_two(7u));
ASSERT_TRUE(entt::is_power_of_two(128u));
ASSERT_FALSE(entt::is_power_of_two(200u));
}
TEST(Memory, FastMod) {