diff options
Diffstat (limited to 'absl/container/fixed_array.h')
| -rw-r--r-- | absl/container/fixed_array.h | 154 |
1 files changed, 94 insertions, 60 deletions
diff --git a/absl/container/fixed_array.h b/absl/container/fixed_array.h index 62600df05b..f480047a5d 100644 --- a/absl/container/fixed_array.h +++ b/absl/container/fixed_array.h @@ -47,6 +47,7 @@ #include "absl/base/macros.h" #include "absl/base/optimization.h" #include "absl/base/port.h" +#include "absl/container/internal/compressed_tuple.h" #include "absl/memory/memory.h" namespace absl { @@ -76,73 +77,99 @@ constexpr static auto kFixedArrayUseDefault = static_cast<size_t>(-1); // heap allocation, it will do so with global `::operator new[]()` and // `::operator delete[]()`, even if T provides class-scope overrides for these // operators. -template <typename T, size_t inlined = kFixedArrayUseDefault> +template <typename T, size_t N = kFixedArrayUseDefault, + typename A = std::allocator<T>> class FixedArray { static_assert(!std::is_array<T>::value || std::extent<T>::value > 0, "Arrays with unknown bounds cannot be used with FixedArray."); + static constexpr size_t kInlineBytesDefault = 256; + using AllocatorTraits = std::allocator_traits<A>; // std::iterator_traits isn't guaranteed to be SFINAE-friendly until C++17, // but this seems to be mostly pedantic. template <typename Iterator> using EnableIfForwardIterator = absl::enable_if_t<std::is_convertible< typename std::iterator_traits<Iterator>::iterator_category, std::forward_iterator_tag>::value>; + static constexpr bool NoexceptCopyable() { + return std::is_nothrow_copy_constructible<StorageElement>::value && + absl::allocator_is_nothrow<allocator_type>::value; + } + static constexpr bool NoexceptMovable() { + return std::is_nothrow_move_constructible<StorageElement>::value && + absl::allocator_is_nothrow<allocator_type>::value; + } + static constexpr bool DefaultConstructorIsNonTrivial() { + return !absl::is_trivially_default_constructible<StorageElement>::value; + } public: - using value_type = T; - using iterator = T*; - using const_iterator = const T*; + using allocator_type = typename AllocatorTraits::allocator_type; + using value_type = typename allocator_type::value_type; + using pointer = typename allocator_type::pointer; + using const_pointer = typename allocator_type::const_pointer; + using reference = typename allocator_type::reference; + using const_reference = typename allocator_type::const_reference; + using size_type = typename allocator_type::size_type; + using difference_type = typename allocator_type::difference_type; + using iterator = pointer; + using const_iterator = const_pointer; using reverse_iterator = std::reverse_iterator<iterator>; using const_reverse_iterator = std::reverse_iterator<const_iterator>; - using reference = T&; - using const_reference = const T&; - using pointer = T*; - using const_pointer = const T*; - using difference_type = ptrdiff_t; - using size_type = size_t; static constexpr size_type inline_elements = - inlined == kFixedArrayUseDefault - ? kInlineBytesDefault / sizeof(value_type) - : inlined; + (N == kFixedArrayUseDefault ? kInlineBytesDefault / sizeof(value_type) + : static_cast<size_type>(N)); - FixedArray(const FixedArray& other) - : FixedArray(other.begin(), other.end()) {} + FixedArray( + const FixedArray& other, + const allocator_type& a = allocator_type()) noexcept(NoexceptCopyable()) + : FixedArray(other.begin(), other.end(), a) {} - FixedArray(FixedArray&& other) noexcept( - absl::conjunction<absl::allocator_is_nothrow<std::allocator<value_type>>, - std::is_nothrow_move_constructible<value_type>>::value) + FixedArray( + FixedArray&& other, + const allocator_type& a = allocator_type()) noexcept(NoexceptMovable()) : FixedArray(std::make_move_iterator(other.begin()), - std::make_move_iterator(other.end())) {} + std::make_move_iterator(other.end()), a) {} // Creates an array object that can store `n` elements. // Note that trivially constructible elements will be uninitialized. - explicit FixedArray(size_type n) : storage_(n) { - absl::memory_internal::uninitialized_default_construct_n(storage_.begin(), - size()); + explicit FixedArray(size_type n, const allocator_type& a = allocator_type()) + : storage_(n, a) { + if (DefaultConstructorIsNonTrivial()) { + memory_internal::ConstructStorage(storage_.alloc(), storage_.begin(), + storage_.end()); + } } // Creates an array initialized with `n` copies of `val`. - FixedArray(size_type n, const value_type& val) : storage_(n) { - std::uninitialized_fill_n(data(), size(), val); + FixedArray(size_type n, const value_type& val, + const allocator_type& a = allocator_type()) + : storage_(n, a) { + memory_internal::ConstructStorage(storage_.alloc(), storage_.begin(), + storage_.end(), val); } + // Creates an array initialized with the size and contents of `init_list`. + FixedArray(std::initializer_list<value_type> init_list, + const allocator_type& a = allocator_type()) + : FixedArray(init_list.begin(), init_list.end(), a) {} + // Creates an array initialized with the elements from the input // range. The array's size will always be `std::distance(first, last)`. // REQUIRES: Iterator must be a forward_iterator or better. template <typename Iterator, EnableIfForwardIterator<Iterator>* = nullptr> - FixedArray(Iterator first, Iterator last) - : storage_(std::distance(first, last)) { - std::uninitialized_copy(first, last, data()); + FixedArray(Iterator first, Iterator last, + const allocator_type& a = allocator_type()) + : storage_(std::distance(first, last), a) { + memory_internal::CopyToStorageFromRange(storage_.alloc(), storage_.begin(), + first, last); } - FixedArray(std::initializer_list<value_type> init_list) - : FixedArray(init_list.begin(), init_list.end()) {} - ~FixedArray() noexcept { - for (const StorageElement& cur : storage_) { - cur.~StorageElement(); + for (auto* cur = storage_.begin(); cur != storage_.end(); ++cur) { + AllocatorTraits::destroy(*storage_.alloc(), cur); } } @@ -332,7 +359,6 @@ class FixedArray { friend bool operator>=(const FixedArray& lhs, const FixedArray& rhs) { return !(lhs < rhs); } - private: // StorageElement // @@ -364,6 +390,8 @@ class FixedArray { using StorageElement = absl::conditional_t<std::is_array<value_type>::value, StorageElementWrapper<value_type>, value_type>; + using StorageElementBuffer = + absl::aligned_storage_t<sizeof(StorageElement), alignof(StorageElement)>; static pointer AsValueType(pointer ptr) { return ptr; } static pointer AsValueType(StorageElementWrapper<value_type>* ptr) { @@ -374,9 +402,6 @@ class FixedArray { static_assert(alignof(StorageElement) == alignof(value_type), ""); struct NonEmptyInlinedStorage { - using StorageElementBuffer = - absl::aligned_storage_t<sizeof(StorageElement), - alignof(StorageElement)>; StorageElement* data() { return reinterpret_cast<StorageElement*>(inlined_storage_.data()); } @@ -386,8 +411,8 @@ class FixedArray { void* RedzoneEnd() { return &redzone_end_ + 1; } #endif // ADDRESS_SANITIZER - void AnnotateConstruct(size_t); - void AnnotateDestruct(size_t); + void AnnotateConstruct(size_type); + void AnnotateDestruct(size_type); ADDRESS_SANITIZER_REDZONE(redzone_begin_); std::array<StorageElementBuffer, inline_elements> inlined_storage_; @@ -396,8 +421,8 @@ class FixedArray { struct EmptyInlinedStorage { StorageElement* data() { return nullptr; } - void AnnotateConstruct(size_t) {} - void AnnotateDestruct(size_t) {} + void AnnotateConstruct(size_type) {} + void AnnotateDestruct(size_type) {} }; using InlinedStorage = @@ -414,48 +439,57 @@ class FixedArray { // class Storage : public InlinedStorage { public: - explicit Storage(size_type n) : data_(CreateStorage(n)), size_(n) {} + Storage(size_type n, const allocator_type& a) + : size_alloc_(n, a), data_(InitializeData()) {} + ~Storage() noexcept { if (UsingInlinedStorage(size())) { - this->AnnotateDestruct(size()); + InlinedStorage::AnnotateDestruct(size()); } else { - std::allocator<StorageElement>().deallocate(begin(), size()); + AllocatorTraits::deallocate(*alloc(), AsValueType(begin()), size()); } } - size_type size() const { return size_; } + size_type size() const { return size_alloc_.template get<0>(); } StorageElement* begin() const { return data_; } StorageElement* end() const { return begin() + size(); } + allocator_type* alloc() { + return std::addressof(size_alloc_.template get<1>()); + } private: static bool UsingInlinedStorage(size_type n) { return n <= inline_elements; } - StorageElement* CreateStorage(size_type n) { - if (UsingInlinedStorage(n)) { - this->AnnotateConstruct(n); + StorageElement* InitializeData() { + if (UsingInlinedStorage(size())) { + InlinedStorage::AnnotateConstruct(size()); return InlinedStorage::data(); } else { - return std::allocator<StorageElement>().allocate(n); + return reinterpret_cast<StorageElement*>( + AllocatorTraits::allocate(*alloc(), size())); } } - StorageElement* const data_; - const size_type size_; + // `CompressedTuple` takes advantage of EBCO for stateless `allocator_type`s + container_internal::CompressedTuple<size_type, allocator_type> size_alloc_; + StorageElement* data_; }; - const Storage storage_; + Storage storage_; }; -template <typename T, size_t N> -constexpr size_t FixedArray<T, N>::inline_elements; +template <typename T, size_t N, typename A> +constexpr size_t FixedArray<T, N, A>::kInlineBytesDefault; -template <typename T, size_t N> -constexpr size_t FixedArray<T, N>::kInlineBytesDefault; +template <typename T, size_t N, typename A> +constexpr typename FixedArray<T, N, A>::size_type + FixedArray<T, N, A>::inline_elements; -template <typename T, size_t N> -void FixedArray<T, N>::NonEmptyInlinedStorage::AnnotateConstruct(size_t n) { +template <typename T, size_t N, typename A> +void FixedArray<T, N, A>::NonEmptyInlinedStorage::AnnotateConstruct( + typename FixedArray<T, N, A>::size_type n) { #ifdef ADDRESS_SANITIZER if (!n) return; ANNOTATE_CONTIGUOUS_CONTAINER(data(), RedzoneEnd(), RedzoneEnd(), data() + n); @@ -464,8 +498,9 @@ void FixedArray<T, N>::NonEmptyInlinedStorage::AnnotateConstruct(size_t n) { static_cast<void>(n); // Mark used when not in asan mode } -template <typename T, size_t N> -void FixedArray<T, N>::NonEmptyInlinedStorage::AnnotateDestruct(size_t n) { +template <typename T, size_t N, typename A> +void FixedArray<T, N, A>::NonEmptyInlinedStorage::AnnotateDestruct( + typename FixedArray<T, N, A>::size_type n) { #ifdef ADDRESS_SANITIZER if (!n) return; ANNOTATE_CONTIGUOUS_CONTAINER(data(), RedzoneEnd(), data() + n, RedzoneEnd()); @@ -473,6 +508,5 @@ void FixedArray<T, N>::NonEmptyInlinedStorage::AnnotateDestruct(size_t n) { #endif // ADDRESS_SANITIZER static_cast<void>(n); // Mark used when not in asan mode } - } // namespace absl #endif // ABSL_CONTAINER_FIXED_ARRAY_H_ |