diff options
Diffstat (limited to 'absl/container/inlined_vector.h')
| -rw-r--r-- | absl/container/inlined_vector.h | 180 |
1 files changed, 54 insertions, 126 deletions
diff --git a/absl/container/inlined_vector.h b/absl/container/inlined_vector.h index 80929e36..68308750 100644 --- a/absl/container/inlined_vector.h +++ b/absl/container/inlined_vector.h @@ -1,4 +1,4 @@ -// Copyright 2018 The Abseil Authors. +// Copyright 2019 The Abseil Authors. // // Licensed under the Apache License, Version 2.0 (the "License"); // you may not use this file except in compliance with the License. @@ -50,6 +50,7 @@ #include "absl/base/internal/throw_delegate.h" #include "absl/base/optimization.h" #include "absl/base/port.h" +#include "absl/container/internal/inlined_vector.h" #include "absl/memory/memory.h" namespace absl { @@ -65,10 +66,10 @@ namespace absl { // designed to cover the same API footprint as covered by `std::vector`. template <typename T, size_t N, typename A = std::allocator<T>> class InlinedVector { - static_assert(N > 0, "InlinedVector requires inline capacity greater than 0"); - constexpr static typename A::size_type GetInlinedCapacity() { - return static_cast<typename A::size_type>(N); - } + using Storage = inlined_vector_internal::InlinedVectorStorage<T, N, A>; + using Tag = typename Storage::Tag; + using AllocatorAndTag = typename Storage::AllocatorAndTag; + using Allocation = typename Storage::Allocation; template <typename Iterator> using IsAtLeastForwardIterator = std::is_convertible< @@ -83,21 +84,21 @@ class InlinedVector { using DisableIfAtLeastForwardIterator = absl::enable_if_t<!IsAtLeastForwardIterator<Iterator>::value>; - using rvalue_reference = typename A::value_type&&; + using rvalue_reference = typename Storage::rvalue_reference; public: - using allocator_type = A; - 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 allocator_type = typename Storage::allocator_type; + using value_type = typename Storage::value_type; + using pointer = typename Storage::pointer; + using const_pointer = typename Storage::const_pointer; + using reference = typename Storage::reference; + using const_reference = typename Storage::const_reference; + using size_type = typename Storage::size_type; + using difference_type = typename Storage::difference_type; + using iterator = typename Storage::iterator; + using const_iterator = typename Storage::const_iterator; + using reverse_iterator = typename Storage::reverse_iterator; + using const_reverse_iterator = typename Storage::const_reverse_iterator; // --------------------------------------------------------------------------- // InlinedVector Constructors and Destructor @@ -105,30 +106,30 @@ class InlinedVector { // Creates an empty inlined vector with a default initialized allocator. InlinedVector() noexcept(noexcept(allocator_type())) - : allocator_and_tag_(allocator_type()) {} + : storage_(allocator_type()) {} // Creates an empty inlined vector with a specified allocator. explicit InlinedVector(const allocator_type& alloc) noexcept - : allocator_and_tag_(alloc) {} + : storage_(alloc) {} // Creates an inlined vector with `n` copies of `value_type()`. explicit InlinedVector(size_type n, const allocator_type& alloc = allocator_type()) - : allocator_and_tag_(alloc) { + : storage_(alloc) { InitAssign(n); } // Creates an inlined vector with `n` copies of `v`. InlinedVector(size_type n, const_reference v, const allocator_type& alloc = allocator_type()) - : allocator_and_tag_(alloc) { + : storage_(alloc) { InitAssign(n, v); } // Creates an inlined vector of copies of the values in `list`. InlinedVector(std::initializer_list<value_type> list, const allocator_type& alloc = allocator_type()) - : allocator_and_tag_(alloc) { + : storage_(alloc) { AppendForwardRange(list.begin(), list.end()); } @@ -142,7 +143,7 @@ class InlinedVector { EnableIfAtLeastForwardIterator<ForwardIterator>* = nullptr> InlinedVector(ForwardIterator first, ForwardIterator last, const allocator_type& alloc = allocator_type()) - : allocator_and_tag_(alloc) { + : storage_(alloc) { AppendForwardRange(first, last); } @@ -152,7 +153,7 @@ class InlinedVector { DisableIfAtLeastForwardIterator<InputIterator>* = nullptr> InlinedVector(InputIterator first, InputIterator last, const allocator_type& alloc = allocator_type()) - : allocator_and_tag_(alloc) { + : storage_(alloc) { std::copy(first, last, std::back_inserter(*this)); } @@ -162,7 +163,7 @@ class InlinedVector { // Creates a copy of an `other` inlined vector using a specified allocator. InlinedVector(const InlinedVector& other, const allocator_type& alloc) - : allocator_and_tag_(alloc) { + : storage_(alloc) { reserve(other.size()); if (allocated()) { UninitializedCopy(other.begin(), other.end(), allocated_space()); @@ -191,7 +192,7 @@ class InlinedVector { InlinedVector(InlinedVector&& other) noexcept( absl::allocator_is_nothrow<allocator_type>::value || std::is_nothrow_move_constructible<value_type>::value) - : allocator_and_tag_(other.allocator()) { + : storage_(other.allocator()) { if (other.allocated()) { // We can just steal the underlying buffer from the source. // That leaves the source empty, so we clear its size. @@ -222,7 +223,7 @@ class InlinedVector { // ownership of `other`'s allocated memory. InlinedVector(InlinedVector&& other, const allocator_type& alloc) noexcept( absl::allocator_is_nothrow<allocator_type>::value) - : allocator_and_tag_(alloc) { + : storage_(alloc) { if (other.allocated()) { if (alloc == other.allocator()) { // We can just steal the allocation from the source. @@ -282,7 +283,8 @@ class InlinedVector { // will no longer be inlined and `capacity()` will equal its capacity on the // allocated heap. size_type capacity() const noexcept { - return allocated() ? allocation().capacity() : GetInlinedCapacity(); + return allocated() ? allocation().capacity() + : Storage::GetInlinedCapacity(); } // `InlinedVector::data()` @@ -800,19 +802,19 @@ class InlinedVector { // `InlinedVector::shrink_to_fit()` // // Reduces memory usage by freeing unused memory. After this call, calls to - // `capacity()` will be equal to `(std::max)(GetInlinedCapacity(), size())`. + // `capacity()` will be equal to `max(Storage::GetInlinedCapacity(), size())`. // - // If `size() <= GetInlinedCapacity()` and the elements are currently stored - // on the heap, they will be moved to the inlined storage and the heap memory - // will be deallocated. + // If `size() <= Storage::GetInlinedCapacity()` and the elements are currently + // stored on the heap, they will be moved to the inlined storage and the heap + // memory will be deallocated. // - // If `size() > GetInlinedCapacity()` and `size() < capacity()` the elements - // will be moved to a smaller heap allocation. + // If `size() > Storage::GetInlinedCapacity()` and `size() < capacity()` the + // elements will be moved to a smaller heap allocation. void shrink_to_fit() { const auto s = size(); if (ABSL_PREDICT_FALSE(!allocated() || s == capacity())) return; - if (s <= GetInlinedCapacity()) { + if (s <= Storage::GetInlinedCapacity()) { // Move the elements to the inlined storage. // We have to do this using a temporary, because `inlined_storage` and // `allocation_storage` are in a union field. @@ -845,88 +847,33 @@ class InlinedVector { template <typename H, typename TheT, size_t TheN, typename TheA> friend auto AbslHashValue(H h, const InlinedVector<TheT, TheN, TheA>& v) -> H; - // Holds whether the vector is allocated or not in the lowest bit and the size - // in the high bits: - // `size_ = (size << 1) | is_allocated;` - class Tag { - public: - Tag() : size_(0) {} - size_type size() const { return size_ / 2; } - void add_size(size_type n) { size_ += n * 2; } - void set_inline_size(size_type n) { size_ = n * 2; } - void set_allocated_size(size_type n) { size_ = (n * 2) + 1; } - bool allocated() const { return size_ % 2; } - - private: - size_type size_; - }; - - // Derives from `allocator_type` to use the empty base class optimization. - // If the `allocator_type` is stateless, we can store our instance for free. - class AllocatorAndTag : private allocator_type { - public: - explicit AllocatorAndTag(const allocator_type& a) : allocator_type(a) {} - - Tag& tag() { return tag_; } - const Tag& tag() const { return tag_; } - - allocator_type& allocator() { return *this; } - const allocator_type& allocator() const { return *this; } - - private: - Tag tag_; - }; - - class Allocation { - public: - Allocation(allocator_type& a, size_type capacity) - : capacity_(capacity), buffer_(Create(a, capacity)) {} - - void Dealloc(allocator_type& a) { - std::allocator_traits<allocator_type>::deallocate(a, buffer_, capacity_); - } - - size_type capacity() const { return capacity_; } - - const_pointer buffer() const { return buffer_; } - - pointer buffer() { return buffer_; } + const Tag& tag() const { return storage_.allocator_and_tag_.tag(); } - private: - static pointer Create(allocator_type& a, size_type n) { - return std::allocator_traits<allocator_type>::allocate(a, n); - } - - size_type capacity_; - pointer buffer_; - }; - - const Tag& tag() const { return allocator_and_tag_.tag(); } - - Tag& tag() { return allocator_and_tag_.tag(); } + Tag& tag() { return storage_.allocator_and_tag_.tag(); } Allocation& allocation() { - return reinterpret_cast<Allocation&>(rep_.allocation_storage.allocation); + return reinterpret_cast<Allocation&>( + storage_.rep_.allocation_storage.allocation); } const Allocation& allocation() const { return reinterpret_cast<const Allocation&>( - rep_.allocation_storage.allocation); + storage_.rep_.allocation_storage.allocation); } void init_allocation(const Allocation& allocation) { - new (&rep_.allocation_storage.allocation) Allocation(allocation); + new (&storage_.rep_.allocation_storage.allocation) Allocation(allocation); } // TODO(absl-team): investigate whether the reinterpret_cast is appropriate. pointer inlined_space() { return reinterpret_cast<pointer>( - std::addressof(rep_.inlined_storage.inlined[0])); + std::addressof(storage_.rep_.inlined_storage.inlined[0])); } const_pointer inlined_space() const { return reinterpret_cast<const_pointer>( - std::addressof(rep_.inlined_storage.inlined[0])); + std::addressof(storage_.rep_.inlined_storage.inlined[0])); } pointer allocated_space() { return allocation().buffer(); } @@ -934,10 +881,12 @@ class InlinedVector { const_pointer allocated_space() const { return allocation().buffer(); } const allocator_type& allocator() const { - return allocator_and_tag_.allocator(); + return storage_.allocator_and_tag_.allocator(); } - allocator_type& allocator() { return allocator_and_tag_.allocator(); } + allocator_type& allocator() { + return storage_.allocator_and_tag_.allocator(); + } bool allocated() const { return tag().allocated(); } @@ -994,7 +943,7 @@ class InlinedVector { const size_type s = size(); assert(s <= capacity()); - size_type target = (std::max)(GetInlinedCapacity(), s + delta); + size_type target = (std::max)(Storage::GetInlinedCapacity(), s + delta); // Compute new capacity by repeatedly doubling current capacity // TODO(psrc): Check and avoid overflow? @@ -1097,7 +1046,7 @@ class InlinedVector { } void InitAssign(size_type n) { - if (n > GetInlinedCapacity()) { + if (n > Storage::GetInlinedCapacity()) { Allocation new_allocation(allocator(), n); init_allocation(new_allocation); UninitializedFill(allocated_space(), allocated_space() + n); @@ -1109,7 +1058,7 @@ class InlinedVector { } void InitAssign(size_type n, const_reference v) { - if (n > GetInlinedCapacity()) { + if (n > Storage::GetInlinedCapacity()) { Allocation new_allocation(allocator(), n); init_allocation(new_allocation); UninitializedFill(allocated_space(), allocated_space() + n, v); @@ -1267,28 +1216,7 @@ class InlinedVector { assert(a->size() == b_size); } - // Stores either the inlined or allocated representation - union Rep { - using ValueTypeBuffer = - absl::aligned_storage_t<sizeof(value_type), alignof(value_type)>; - using AllocationBuffer = - absl::aligned_storage_t<sizeof(Allocation), alignof(Allocation)>; - - // Structs wrap the buffers to perform indirection that solves a bizarre - // compilation error on Visual Studio (all known versions). - struct InlinedRep { - ValueTypeBuffer inlined[N]; - }; - struct AllocatedRep { - AllocationBuffer allocation; - }; - - InlinedRep inlined_storage; - AllocatedRep allocation_storage; - }; - - AllocatorAndTag allocator_and_tag_; - Rep rep_; + Storage storage_; }; // ----------------------------------------------------------------------------- |