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Add span::subspan

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This commit is contained in:
Steven Le Rouzic
2024-11-04 22:09:50 +01:00
parent cb5967d8f4
commit 8b1110c61c
3 changed files with 182 additions and 13 deletions
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14
MODULE.bazel.lock generated
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@ -64,20 +64,20 @@
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@ -92,7 +92,7 @@
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55
asl/span.hpp
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@ -13,7 +13,12 @@ static constexpr int64_t dynamic_size = -1;
template<is_object T, int64_t kSize = dynamic_size>
class span
{
static constexpr bool kIsDynamic = kSize < 0;
static constexpr bool is_dynamic(int64_t size)
{
return size < 0;
}
static constexpr bool kIsDynamic = is_dynamic(kSize);
using SizeType = select_t<kIsDynamic, int64_t, empty>;
@ -21,7 +26,7 @@ class span
ASL_NO_UNIQUE_ADDRESS SizeType m_size{};
public:
constexpr span() = default;
constexpr span() requires (kIsDynamic || kSize == 0) = default;
constexpr span(T* data, int64_t size)
requires kIsDynamic
@ -55,7 +60,7 @@ public:
requires (
(
kIsDynamic ||
span<U, kOtherSize>::kIsDynamic ||
is_dynamic(kOtherSize) ||
kOtherSize == kSize
) && convertible_from<T(&)[], U(&)[]>
)
@ -92,11 +97,49 @@ public:
return m_data[i]; // NOLINT(*-pointer-arithmetic)
}
// @Todo subspan, first, last
// @Todo first, last
// @Todo as_(mutable_)bytes
template<is_object U, int64_t kOtherSize>
friend class span;
template<int64_t kOffset, int64_t kSubSize = dynamic_size>
constexpr auto subspan() const
requires (
kOffset >= 0 &&
(kIsDynamic || kOffset <= kSize) &&
(kIsDynamic || is_dynamic(kSubSize) || kSubSize <= kSize - kOffset)
)
{
ASL_ASSERT(kOffset <= size());
if constexpr (is_dynamic(kSubSize))
{
if constexpr (kIsDynamic)
{
return span<T>(data() + kOffset, size() - kOffset);
}
else
{
return span<T, kSize - kOffset>(data() + kOffset, size() - kOffset);
}
}
else
{
ASL_ASSERT(kSubSize <= size() - kOffset);
return span<T, kSubSize>(data() + kOffset, kSubSize);
}
}
constexpr span<T> subspan(int64_t offset, int64_t sub_size = dynamic_size) const
{
ASL_ASSERT(offset <= size());
if (is_dynamic(sub_size))
{
return span<T>{ data() + offset, size() - offset };
}
ASL_ASSERT(sub_size <= size() - offset);
return span<T>{ data() + offset, sub_size };
}
};
} // namespace asl

126
asl/tests/span_tests.cpp
View File

@ -38,6 +38,10 @@ ASL_TEST(from_array_dynamic)
ASL_TEST_EXPECT(span[2] == 3);
}
static_assert(asl::default_constructible<asl::span<int>>);
static_assert(asl::default_constructible<asl::span<int, 0>>);
static_assert(!asl::default_constructible<asl::span<int, 8>>);
static_assert(asl::constructible_from<asl::span<int32_t>, int32_t(&)[8]>);
static_assert(!asl::constructible_from<asl::span<int32_t>, const int32_t(&)[8]>);
static_assert(asl::constructible_from<asl::span<const int32_t>, int32_t(&)[8]>);
@ -89,3 +93,125 @@ ASL_TEST(conversion)
ASL_TEST_EXPECT(span4[1] == 2);
ASL_TEST_EXPECT(span4[2] == 3);
}
template<typename Span, int64_t kOffset, int64_t kSize = asl::dynamic_size>
[[maybe_unused]] static auto try_static_subspan(int)
-> decltype(asl::declval<Span>().template subspan<kOffset, kSize>());
template<typename, int64_t, int64_t>
[[maybe_unused]] static auto try_static_subspan(...) -> asl::empty;
template<typename Span, int64_t kOffset, int64_t kSize = asl::dynamic_size>
concept invalid_subspan = asl::same_as<decltype(try_static_subspan<Span, kOffset, kSize>(0)), asl::empty>;
static_assert(asl::same_as<asl::span<int, 4>,
decltype(asl::declval<asl::span<int, 4>>().subspan<0>())>);
static_assert(asl::same_as<asl::span<int, 3>,
decltype(asl::declval<asl::span<int, 4>>().subspan<1>())>);
static_assert(asl::same_as<asl::span<int, 2>,
decltype(asl::declval<asl::span<int, 4>>().subspan<2>())>);
static_assert(asl::same_as<asl::span<int, 1>,
decltype(asl::declval<asl::span<int, 4>>().subspan<3>())>);
static_assert(asl::same_as<asl::span<int, 0>,
decltype(asl::declval<asl::span<int, 4>>().subspan<4>())>);
static_assert(invalid_subspan<asl::span<int, 4>, 5>);
static_assert(asl::same_as<asl::span<int>,
decltype(asl::declval<asl::span<int>>().subspan<0>())>);
static_assert(asl::same_as<asl::span<int, 4>,
decltype(asl::declval<asl::span<int>>().subspan<0, 4>())>);
static_assert(asl::same_as<asl::span<int, 4>,
decltype(asl::declval<asl::span<int, 4>>().subspan<0, 4>())>);
static_assert(asl::same_as<asl::span<int, 2>,
decltype(asl::declval<asl::span<int, 4>>().subspan<1, 2>())>);
static_assert(asl::same_as<asl::span<int, 2>,
decltype(asl::declval<asl::span<int, 4>>().subspan<2, 2>())>);
static_assert(invalid_subspan<asl::span<int, 4>, 2, 3>);
ASL_TEST(subspan_static_from_static)
{
int array[] = {1, 2, 3, 4};
asl::span<int, 4> span{array};
auto s1 = span.subspan<0>();
ASL_TEST_EXPECT(s1.size() == 4);
ASL_TEST_ASSERT(s1[0] == 1);
ASL_TEST_ASSERT(s1[1] == 2);
ASL_TEST_ASSERT(s1[2] == 3);
ASL_TEST_ASSERT(s1[3] == 4);
auto s2 = span.subspan<2>();
ASL_TEST_EXPECT(s2.size() == 2);
ASL_TEST_ASSERT(s2[0] == 3);
ASL_TEST_ASSERT(s2[1] == 4);
auto s3 = span.subspan<4>();
ASL_TEST_EXPECT(s3.size() == 0);
auto s4 = span.subspan<1, 2>();
ASL_TEST_EXPECT(s4.size() == 2);
ASL_TEST_ASSERT(s4[0] == 2);
ASL_TEST_ASSERT(s4[1] == 3);
}
ASL_TEST(subspan_static_from_dynamic)
{
int array[] = {1, 2, 3, 4};
asl::span<int> span{array};
auto s1 = span.subspan<0>();
ASL_TEST_EXPECT(s1.size() == 4);
ASL_TEST_ASSERT(s1[0] == 1);
ASL_TEST_ASSERT(s1[1] == 2);
ASL_TEST_ASSERT(s1[2] == 3);
ASL_TEST_ASSERT(s1[3] == 4);
auto s2 = span.subspan<2>();
ASL_TEST_EXPECT(s2.size() == 2);
ASL_TEST_ASSERT(s2[0] == 3);
ASL_TEST_ASSERT(s2[1] == 4);
auto s3 = span.subspan<4>();
ASL_TEST_EXPECT(s3.size() == 0);
auto s4 = span.subspan<1, 2>();
ASL_TEST_EXPECT(s4.size() == 2);
ASL_TEST_ASSERT(s4[0] == 2);
ASL_TEST_ASSERT(s4[1] == 3);
}
ASL_TEST(subspan_dynamic)
{
int array[] = {1, 2, 3, 4};
asl::span<int> span{array};
auto s1 = span.subspan(0);
ASL_TEST_EXPECT(s1.size() == 4);
ASL_TEST_ASSERT(s1[0] == 1);
ASL_TEST_ASSERT(s1[1] == 2);
ASL_TEST_ASSERT(s1[2] == 3);
ASL_TEST_ASSERT(s1[3] == 4);
auto s2 = span.subspan(2);
ASL_TEST_EXPECT(s2.size() == 2);
ASL_TEST_ASSERT(s2[0] == 3);
ASL_TEST_ASSERT(s2[1] == 4);
auto s3 = span.subspan(4);
ASL_TEST_EXPECT(s3.size() == 0);
auto s4 = span.subspan(1, 2);
ASL_TEST_EXPECT(s4.size() == 2);
ASL_TEST_ASSERT(s4[0] == 2);
ASL_TEST_ASSERT(s4[1] == 3);
}