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-rw-r--r--absl/container/fixed_array.h154
1 files changed, 94 insertions, 60 deletions
diff --git a/absl/container/fixed_array.h b/absl/container/fixed_array.h
index 62600df0..f480047a 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_
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