+++ /dev/null
-// Copyright (c) 2018-Present Red Hat Inc. All rights reserved.
-//
-// Copyright (c) 2011-2018, Facebook, Inc. All rights reserved.
-// This source code is licensed under both the GPLv2 and Apache 2.0 License
-
-#ifndef CEPH_AUTOVECTOR_H
-#define CEPH_AUTOVECTOR_H
-
-#include <algorithm>
-#include <cassert>
-#include <initializer_list>
-#include <iterator>
-#include <stdexcept>
-#include <vector>
-
-#include "include/ceph_assert.h"
-
-// A vector that leverages pre-allocated stack-based array to achieve better
-// performance for array with small amount of items.
-//
-// The interface resembles that of vector, but with less features since we aim
-// to solve the problem that we have in hand, rather than implementing a
-// full-fledged generic container.
-//
-// Currently we don't support:
-// * reserve()/shrink_to_fit()
-// If used correctly, in most cases, people should not touch the
-// underlying vector at all.
-// * random insert()/erase(), please only use push_back()/pop_back().
-// * No move/swap operations. Each autovector instance has a
-// stack-allocated array and if we want support move/swap operations, we
-// need to copy the arrays other than just swapping the pointers. In this
-// case we'll just explicitly forbid these operations since they may
-// lead users to make false assumption by thinking they are inexpensive
-// operations.
-//
-// Naming style of public methods almost follows that of the STL's.
-namespace ceph {
-
-template <class T, size_t kSize = 8>
-class autovector {
- public:
- // General STL-style container member types.
- typedef T value_type;
- typedef typename std::vector<T>::difference_type difference_type;
- typedef typename std::vector<T>::size_type size_type;
- typedef value_type& reference;
- typedef const value_type& const_reference;
- typedef value_type* pointer;
- typedef const value_type* const_pointer;
-
- // This class is the base for regular/const iterator
- template <class TAutoVector, class TValueType>
- class iterator_impl {
- public:
- // -- iterator traits
- typedef iterator_impl<TAutoVector, TValueType> self_type;
- typedef TValueType value_type;
- typedef TValueType& reference;
- typedef TValueType* pointer;
- typedef typename TAutoVector::difference_type difference_type;
- typedef std::random_access_iterator_tag iterator_category;
-
- iterator_impl(TAutoVector* vect, size_t index)
- : vect_(vect), index_(index) {};
- iterator_impl(const iterator_impl&) = default;
- ~iterator_impl() {}
- iterator_impl& operator=(const iterator_impl&) = default;
-
- // -- Advancement
- // ++iterator
- self_type& operator++() {
- ++index_;
- return *this;
- }
-
- // iterator++
- self_type operator++(int) {
- auto old = *this;
- ++index_;
- return old;
- }
-
- // --iterator
- self_type& operator--() {
- --index_;
- return *this;
- }
-
- // iterator--
- self_type operator--(int) {
- auto old = *this;
- --index_;
- return old;
- }
-
- self_type operator-(difference_type len) const {
- return self_type(vect_, index_ - len);
- }
-
- difference_type operator-(const self_type& other) const {
- ceph_assert(vect_ == other.vect_);
- return index_ - other.index_;
- }
-
- self_type operator+(difference_type len) const {
- return self_type(vect_, index_ + len);
- }
-
- self_type& operator+=(difference_type len) {
- index_ += len;
- return *this;
- }
-
- self_type& operator-=(difference_type len) {
- index_ -= len;
- return *this;
- }
-
- // -- Reference
- reference operator*() {
- ceph_assert(vect_->size() >= index_);
- return (*vect_)[index_];
- }
-
- const_reference operator*() const {
- ceph_assert(vect_->size() >= index_);
- return (*vect_)[index_];
- }
-
- pointer operator->() {
- ceph_assert(vect_->size() >= index_);
- return &(*vect_)[index_];
- }
-
- const_pointer operator->() const {
- ceph_assert(vect_->size() >= index_);
- return &(*vect_)[index_];
- }
-
-
- // -- Logical Operators
- bool operator==(const self_type& other) const {
- ceph_assert(vect_ == other.vect_);
- return index_ == other.index_;
- }
-
- bool operator!=(const self_type& other) const { return !(*this == other); }
-
- bool operator>(const self_type& other) const {
- ceph_assert(vect_ == other.vect_);
- return index_ > other.index_;
- }
-
- bool operator<(const self_type& other) const {
- ceph_assert(vect_ == other.vect_);
- return index_ < other.index_;
- }
-
- bool operator>=(const self_type& other) const {
- ceph_assert(vect_ == other.vect_);
- return index_ >= other.index_;
- }
-
- bool operator<=(const self_type& other) const {
- ceph_assert(vect_ == other.vect_);
- return index_ <= other.index_;
- }
-
- private:
- TAutoVector* vect_ = nullptr;
- size_t index_ = 0;
- };
-
- typedef iterator_impl<autovector, value_type> iterator;
- typedef iterator_impl<const autovector, const value_type> const_iterator;
- typedef std::reverse_iterator<iterator> reverse_iterator;
- typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
-
- autovector() = default;
-
- autovector(std::initializer_list<T> init_list) {
- for (const T& item : init_list) {
- push_back(item);
- }
- }
-
- ~autovector() = default;
-
- // -- Immutable operations
- // Indicate if all data resides in in-stack data structure.
- bool only_in_stack() const {
- // If no element was inserted at all, the vector's capacity will be `0`.
- return vect_.capacity() == 0;
- }
-
- size_type size() const { return num_stack_items_ + vect_.size(); }
-
- // resize does not guarantee anything about the contents of the newly
- // available elements
- void resize(size_type n) {
- if (n > kSize) {
- vect_.resize(n - kSize);
- num_stack_items_ = kSize;
- } else {
- vect_.clear();
- num_stack_items_ = n;
- }
- }
-
- bool empty() const { return size() == 0; }
-
- const_reference operator[](size_type n) const {
- ceph_assert(n < size());
- return n < kSize ? values_[n] : vect_[n - kSize];
- }
-
- reference operator[](size_type n) {
- ceph_assert(n < size());
- return n < kSize ? values_[n] : vect_[n - kSize];
- }
-
- const_reference at(size_type n) const {
- ceph_assert(n < size());
- return (*this)[n];
- }
-
- reference at(size_type n) {
- ceph_assert(n < size());
- return (*this)[n];
- }
-
- reference front() {
- ceph_assert(!empty());
- return *begin();
- }
-
- const_reference front() const {
- ceph_assert(!empty());
- return *begin();
- }
-
- reference back() {
- ceph_assert(!empty());
- return *(end() - 1);
- }
-
- const_reference back() const {
- ceph_assert(!empty());
- return *(end() - 1);
- }
-
- // -- Mutable Operations
- void push_back(T&& item) {
- if (num_stack_items_ < kSize) {
- values_[num_stack_items_++] = std::move(item);
- } else {
- vect_.push_back(item);
- }
- }
-
- void push_back(const T& item) {
- if (num_stack_items_ < kSize) {
- values_[num_stack_items_++] = item;
- } else {
- vect_.push_back(item);
- }
- }
-
- template <class... Args>
- void emplace_back(Args&&... args) {
- push_back(value_type(args...));
- }
-
- void pop_back() {
- ceph_assert(!empty());
- if (!vect_.empty()) {
- vect_.pop_back();
- } else {
- --num_stack_items_;
- }
- }
-
- void clear() {
- num_stack_items_ = 0;
- vect_.clear();
- }
-
- // -- Copy and Assignment
- autovector& assign(const autovector& other);
-
- autovector(const autovector& other) { assign(other); }
-
- autovector& operator=(const autovector& other) { return assign(other); }
-
- // -- Iterator Operations
- iterator begin() { return iterator(this, 0); }
-
- const_iterator begin() const { return const_iterator(this, 0); }
-
- iterator end() { return iterator(this, this->size()); }
-
- const_iterator end() const { return const_iterator(this, this->size()); }
-
- reverse_iterator rbegin() { return reverse_iterator(end()); }
-
- const_reverse_iterator rbegin() const {
- return const_reverse_iterator(end());
- }
-
- reverse_iterator rend() { return reverse_iterator(begin()); }
-
- const_reverse_iterator rend() const {
- return const_reverse_iterator(begin());
- }
-
- private:
- size_type num_stack_items_ = 0; // current number of items
- value_type values_[kSize]; // the first `kSize` items
- // used only if there are more than `kSize` items.
- std::vector<T> vect_;
-};
-
-template <class T, size_t kSize>
-autovector<T, kSize>& autovector<T, kSize>::assign(const autovector& other) {
- // copy the internal vector
- vect_.assign(other.vect_.begin(), other.vect_.end());
-
- // copy array
- num_stack_items_ = other.num_stack_items_;
- std::copy(other.values_, other.values_ + num_stack_items_, values_);
-
- return *this;
-}
-} // namespace ceph
-#endif // CEPH_AUTOVECTOR_H
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