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// 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.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#ifndef ABSL_CONTAINER_INTERNAL_INLINED_VECTOR_INTERNAL_H_
#define ABSL_CONTAINER_INTERNAL_INLINED_VECTOR_INTERNAL_H_
#include <cstddef>
#include <cstring>
#include <iterator>
#include <memory>
#include <utility>
#include "absl/container/internal/compressed_tuple.h"
#include "absl/memory/memory.h"
#include "absl/meta/type_traits.h"
namespace absl {
namespace inlined_vector_internal {
template <typename Iterator>
using IsAtLeastForwardIterator = std::is_convertible<
typename std::iterator_traits<Iterator>::iterator_category,
std::forward_iterator_tag>;
template <typename AllocatorType, typename ValueType, typename SizeType>
void DestroyElements(AllocatorType* alloc_ptr, ValueType* destroy_first,
SizeType destroy_size) {
using AllocatorTraits = absl::allocator_traits<AllocatorType>;
for (SizeType i = 0; i < destroy_size; ++i) {
AllocatorTraits::destroy(*alloc_ptr, destroy_first + i);
}
#ifndef NDEBUG
// Overwrite unused memory with `0xab` so we can catch uninitialized usage.
//
// Cast to `void*` to tell the compiler that we don't care that we might be
// scribbling on a vtable pointer.
void* memory = reinterpret_cast<void*>(destroy_first);
size_t memory_size = sizeof(ValueType) * destroy_size;
std::memset(memory, 0xab, memory_size);
#endif // NDEBUG
}
template <typename AllocatorType>
struct StorageView {
using pointer = typename AllocatorType::pointer;
using size_type = typename AllocatorType::size_type;
pointer data;
size_type size;
size_type capacity;
};
template <typename T, size_t N, typename A>
class Storage {
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 rvalue_reference = typename allocator_type::value_type&&;
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 AllocatorTraits = absl::allocator_traits<allocator_type>;
using StorageView = inlined_vector_internal::StorageView<allocator_type>;
Storage() : metadata_() {}
explicit Storage(const allocator_type& alloc)
: metadata_(alloc, /* empty and inlined */ 0) {}
~Storage() { DestroyAndDeallocate(); }
size_type GetSize() const { return GetSizeAndIsAllocated() >> 1; }
bool GetIsAllocated() const { return GetSizeAndIsAllocated() & 1; }
pointer GetInlinedData() {
return reinterpret_cast<pointer>(
std::addressof(data_.inlined.inlined_data[0]));
}
const_pointer GetInlinedData() const {
return reinterpret_cast<const_pointer>(
std::addressof(data_.inlined.inlined_data[0]));
}
pointer GetAllocatedData() { return data_.allocated.allocated_data; }
const_pointer GetAllocatedData() const {
return data_.allocated.allocated_data;
}
size_type GetAllocatedCapacity() const {
return data_.allocated.allocated_capacity;
}
StorageView MakeStorageView() {
return GetIsAllocated() ? StorageView{GetAllocatedData(), GetSize(),
GetAllocatedCapacity()}
: StorageView{GetInlinedData(), GetSize(),
static_cast<size_type>(N)};
}
allocator_type* GetAllocPtr() {
return std::addressof(metadata_.template get<0>());
}
const allocator_type* GetAllocPtr() const {
return std::addressof(metadata_.template get<0>());
}
void SetAllocatedSize(size_type size) {
GetSizeAndIsAllocated() = (size << 1) | static_cast<size_type>(1);
}
void SetInlinedSize(size_type size) { GetSizeAndIsAllocated() = size << 1; }
void AddSize(size_type count) { GetSizeAndIsAllocated() += count << 1; }
void SetAllocatedData(pointer data, size_type capacity) {
data_.allocated.allocated_data = data;
data_.allocated.allocated_capacity = capacity;
}
void SwapSizeAndIsAllocated(Storage* other) {
using std::swap;
swap(GetSizeAndIsAllocated(), other->GetSizeAndIsAllocated());
}
void SwapAllocatedSizeAndCapacity(Storage* other) {
using std::swap;
swap(data_.allocated, other->data_.allocated);
}
void DestroyAndDeallocate();
private:
size_type& GetSizeAndIsAllocated() { return metadata_.template get<1>(); }
const size_type& GetSizeAndIsAllocated() const {
return metadata_.template get<1>();
}
using Metadata =
container_internal::CompressedTuple<allocator_type, size_type>;
struct Allocated {
pointer allocated_data;
size_type allocated_capacity;
};
struct Inlined {
using InlinedDataElement =
absl::aligned_storage_t<sizeof(value_type), alignof(value_type)>;
InlinedDataElement inlined_data[N];
};
union Data {
Allocated allocated;
Inlined inlined;
};
Metadata metadata_;
Data data_;
};
template <typename T, size_t N, typename A>
void Storage<T, N, A>::DestroyAndDeallocate() {
namespace ivi = inlined_vector_internal;
StorageView storage_view = MakeStorageView();
ivi::DestroyElements(GetAllocPtr(), storage_view.data, storage_view.size);
if (GetIsAllocated()) {
AllocatorTraits::deallocate(*GetAllocPtr(), storage_view.data,
storage_view.capacity);
}
}
} // namespace inlined_vector_internal
} // namespace absl
#endif // ABSL_CONTAINER_INTERNAL_INLINED_VECTOR_INTERNAL_H_
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