tvl-depot/absl/container/inlined_vector.h
Abseil Team 3837bd9aae Changes imported from Abseil "staging" branch:
- 7349efb2d18db3a019034f66502b67f7461c15ae Reword the noexcept specification for InlinedVector's def... by Jon Cohen <cohenjon@google.com>
  - f3576b18d039a0c8b533f05ac496fa8d7ff3b207 Remove an unneeded comment in call_once.h by Jon Cohen <cohenjon@google.com>

GitOrigin-RevId: 7349efb2d18db3a019034f66502b67f7461c15ae
Change-Id: I398888e6a82ccd69e23ffc0af9eb198d25e57e02
2018-03-19 15:38:35 -04:00

1384 lines
48 KiB
C++

// Copyright 2017 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
//
// http://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.
//
// -----------------------------------------------------------------------------
// File: inlined_vector.h
// -----------------------------------------------------------------------------
//
// This header file contains the declaration and definition of an "inlined
// vector" which behaves in an equivalent fashion to a `std::vector`, except
// that storage for small sequences of the vector are provided inline without
// requiring any heap allocation.
// An `absl::InlinedVector<T,N>` specifies the size N at which to inline as one
// of its template parameters. Vectors of length <= N are provided inline.
// Typically N is very small (e.g., 4) so that sequences that are expected to be
// short do not require allocations.
// An `absl::InlinedVector` does not usually require a specific allocator; if
// the inlined vector grows beyond its initial constraints, it will need to
// allocate (as any normal `std::vector` would) and it will generally use the
// default allocator in that case; optionally, a custom allocator may be
// specified using an `absl::InlinedVector<T,N,A>` construction.
#ifndef ABSL_CONTAINER_INLINED_VECTOR_H_
#define ABSL_CONTAINER_INLINED_VECTOR_H_
#include <algorithm>
#include <cassert>
#include <cstddef>
#include <cstdlib>
#include <cstring>
#include <initializer_list>
#include <iterator>
#include <memory>
#include <type_traits>
#include <utility>
#include "absl/algorithm/algorithm.h"
#include "absl/base/internal/throw_delegate.h"
#include "absl/base/optimization.h"
#include "absl/base/port.h"
#include "absl/memory/memory.h"
namespace absl {
// -----------------------------------------------------------------------------
// InlinedVector
// -----------------------------------------------------------------------------
//
// An `absl::InlinedVector` is designed to be a drop-in replacement for
// `std::vector` for use cases where the vector's size is sufficiently small
// that it can be inlined. If the inlined vector does grow beyond its estimated
// size, it will trigger an initial allocation on the heap, and will behave as a
// `std:vector`. The API of the `absl::InlinedVector` within this file is
// 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 {
using AllocatorTraits = std::allocator_traits<A>;
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>;
InlinedVector() noexcept(noexcept(allocator_type()))
: allocator_and_tag_(allocator_type()) {}
explicit InlinedVector(const allocator_type& alloc) noexcept
: allocator_and_tag_(alloc) {}
// Create a vector with n copies of value_type().
explicit InlinedVector(size_type n) : allocator_and_tag_(allocator_type()) {
InitAssign(n);
}
// Create a vector with n copies of elem
InlinedVector(size_type n, const value_type& elem,
const allocator_type& alloc = allocator_type())
: allocator_and_tag_(alloc) {
InitAssign(n, elem);
}
// Create and initialize with the elements [first .. last).
// The unused enable_if argument restricts this constructor so that it is
// elided when value_type is an integral type. This prevents ambiguous
// interpretation between a call to this constructor with two integral
// arguments and a call to the preceding (n, elem) constructor.
template <typename InputIterator>
InlinedVector(
InputIterator first, InputIterator last,
const allocator_type& alloc = allocator_type(),
typename std::enable_if<!std::is_integral<InputIterator>::value>::type* =
nullptr)
: allocator_and_tag_(alloc) {
AppendRange(first, last);
}
InlinedVector(std::initializer_list<value_type> init,
const allocator_type& alloc = allocator_type())
: allocator_and_tag_(alloc) {
AppendRange(init.begin(), init.end());
}
InlinedVector(const InlinedVector& v);
InlinedVector(const InlinedVector& v, const allocator_type& alloc);
// This move constructor does not allocate and only moves the underlying
// objects, so its `noexcept` specification depends on whether moving the
// underlying objects can throw or not. We assume
// a) move constructors should only throw due to allocation failure and
// b) if `value_type`'s move constructor allocates, it uses the same
// allocation function as the `InlinedVector`'s allocator, so the move
// constructor is non-throwing if the allocator is non-throwing or
// `value_type`'s move constructor is specified as `noexcept`.
InlinedVector(InlinedVector&& v) noexcept(
absl::allocator_is_nothrow<allocator_type>::value ||
std::is_nothrow_move_constructible<value_type>::value);
// This move constructor allocates and also moves the underlying objects, so
// its `noexcept` specification depends on whether the allocation can throw
// and whether moving the underlying objects can throw. Based on the same
// assumptions above, the `noexcept` specification is dominated by whether the
// allocation can throw regardless of whether `value_type`'s move constructor
// is specified as `noexcept`.
InlinedVector(InlinedVector&& v, const allocator_type& alloc) noexcept(
absl::allocator_is_nothrow<allocator_type>::value);
~InlinedVector() { clear(); }
InlinedVector& operator=(const InlinedVector& v) {
if (this == &v) {
return *this;
}
// Optimized to avoid reallocation.
// Prefer reassignment to copy construction for elements.
if (size() < v.size()) { // grow
reserve(v.size());
std::copy(v.begin(), v.begin() + size(), begin());
std::copy(v.begin() + size(), v.end(), std::back_inserter(*this));
} else { // maybe shrink
erase(begin() + v.size(), end());
std::copy(v.begin(), v.end(), begin());
}
return *this;
}
InlinedVector& operator=(InlinedVector&& v) {
if (this == &v) {
return *this;
}
if (v.allocated()) {
clear();
tag().set_allocated_size(v.size());
init_allocation(v.allocation());
v.tag() = Tag();
} else {
if (allocated()) clear();
// Both are inlined now.
if (size() < v.size()) {
auto mid = std::make_move_iterator(v.begin() + size());
std::copy(std::make_move_iterator(v.begin()), mid, begin());
UninitializedCopy(mid, std::make_move_iterator(v.end()), end());
} else {
auto new_end = std::copy(std::make_move_iterator(v.begin()),
std::make_move_iterator(v.end()), begin());
Destroy(new_end, end());
}
tag().set_inline_size(v.size());
}
return *this;
}
InlinedVector& operator=(std::initializer_list<value_type> init) {
AssignRange(init.begin(), init.end());
return *this;
}
// InlinedVector::assign()
//
// Replaces the contents of the inlined vector with copies of those in the
// iterator range [first, last).
template <typename InputIterator>
void assign(
InputIterator first, InputIterator last,
typename std::enable_if<!std::is_integral<InputIterator>::value>::type* =
nullptr) {
AssignRange(first, last);
}
// Overload of `InlinedVector::assign()` to take values from elements of an
// initializer list
void assign(std::initializer_list<value_type> init) {
AssignRange(init.begin(), init.end());
}
// Overload of `InlinedVector::assign()` to replace the first `n` elements of
// the inlined vector with `elem` values.
void assign(size_type n, const value_type& elem) {
if (n <= size()) { // Possibly shrink
std::fill_n(begin(), n, elem);
erase(begin() + n, end());
return;
}
// Grow
reserve(n);
std::fill_n(begin(), size(), elem);
if (allocated()) {
UninitializedFill(allocated_space() + size(), allocated_space() + n,
elem);
tag().set_allocated_size(n);
} else {
UninitializedFill(inlined_space() + size(), inlined_space() + n, elem);
tag().set_inline_size(n);
}
}
// InlinedVector::size()
//
// Returns the number of elements in the inlined vector.
size_type size() const noexcept { return tag().size(); }
// InlinedVector::empty()
//
// Checks if the inlined vector has no elements.
bool empty() const noexcept { return (size() == 0); }
// InlinedVector::capacity()
//
// Returns the number of elements that can be stored in an inlined vector
// without requiring a reallocation of underlying memory. Note that for
// most inlined vectors, `capacity()` should equal its initial size `N`; for
// inlined vectors which exceed this capacity, they will no longer be inlined,
// and `capacity()` will equal its capacity on the allocated heap.
size_type capacity() const noexcept {
return allocated() ? allocation().capacity() : N;
}
// InlinedVector::max_size()
//
// Returns the maximum number of elements the vector can hold.
size_type max_size() const noexcept {
// One bit of the size storage is used to indicate whether the inlined
// vector is allocated; as a result, the maximum size of the container that
// we can express is half of the max for our size type.
return std::numeric_limits<size_type>::max() / 2;
}
// InlinedVector::data()
//
// Returns a const T* pointer to elements of the inlined vector. This pointer
// can be used to access (but not modify) the contained elements.
// Only results within the range `[0,size())` are defined.
const_pointer data() const noexcept {
return allocated() ? allocated_space() : inlined_space();
}
// Overload of InlinedVector::data() to return a T* pointer to elements of the
// inlined vector. This pointer can be used to access and modify the contained
// elements.
pointer data() noexcept {
return allocated() ? allocated_space() : inlined_space();
}
// InlinedVector::clear()
//
// Removes all elements from the inlined vector.
void clear() noexcept {
size_type s = size();
if (allocated()) {
Destroy(allocated_space(), allocated_space() + s);
allocation().Dealloc(allocator());
} else if (s != 0) { // do nothing for empty vectors
Destroy(inlined_space(), inlined_space() + s);
}
tag() = Tag();
}
// InlinedVector::at()
//
// Returns the ith element of an inlined vector.
const value_type& at(size_type i) const {
if (ABSL_PREDICT_FALSE(i >= size())) {
base_internal::ThrowStdOutOfRange(
"InlinedVector::at failed bounds check");
}
return data()[i];
}
// InlinedVector::operator[]
//
// Returns the ith element of an inlined vector using the array operator.
const value_type& operator[](size_type i) const {
assert(i < size());
return data()[i];
}
// Overload of InlinedVector::at() to return the ith element of an inlined
// vector.
value_type& at(size_type i) {
if (i >= size()) {
base_internal::ThrowStdOutOfRange(
"InlinedVector::at failed bounds check");
}
return data()[i];
}
// Overload of InlinedVector::operator[] to return the ith element of an
// inlined vector.
value_type& operator[](size_type i) {
assert(i < size());
return data()[i];
}
// InlinedVector::back()
//
// Returns a reference to the last element of an inlined vector.
value_type& back() {
assert(!empty());
return at(size() - 1);
}
// Overload of InlinedVector::back() returns a reference to the last element
// of an inlined vector of const values.
const value_type& back() const {
assert(!empty());
return at(size() - 1);
}
// InlinedVector::front()
//
// Returns a reference to the first element of an inlined vector.
value_type& front() {
assert(!empty());
return at(0);
}
// Overload of InlinedVector::front() returns a reference to the first element
// of an inlined vector of const values.
const value_type& front() const {
assert(!empty());
return at(0);
}
// InlinedVector::emplace_back()
//
// Constructs and appends an object to the inlined vector.
//
// Returns a reference to the inserted element.
template <typename... Args>
value_type& emplace_back(Args&&... args) {
size_type s = size();
assert(s <= capacity());
if (ABSL_PREDICT_FALSE(s == capacity())) {
return GrowAndEmplaceBack(std::forward<Args>(args)...);
}
assert(s < capacity());
value_type* space;
if (allocated()) {
tag().set_allocated_size(s + 1);
space = allocated_space();
} else {
tag().set_inline_size(s + 1);
space = inlined_space();
}
return Construct(space + s, std::forward<Args>(args)...);
}
// InlinedVector::push_back()
//
// Appends a const element to the inlined vector.
void push_back(const value_type& t) { emplace_back(t); }
// Overload of InlinedVector::push_back() to append a move-only element to the
// inlined vector.
void push_back(value_type&& t) { emplace_back(std::move(t)); }
// InlinedVector::pop_back()
//
// Removes the last element (which is destroyed) in the inlined vector.
void pop_back() {
assert(!empty());
size_type s = size();
if (allocated()) {
Destroy(allocated_space() + s - 1, allocated_space() + s);
tag().set_allocated_size(s - 1);
} else {
Destroy(inlined_space() + s - 1, inlined_space() + s);
tag().set_inline_size(s - 1);
}
}
// InlinedVector::resize()
//
// Resizes the inlined vector to contain `n` elements. If `n` is smaller than
// the inlined vector's current size, extra elements are destroyed. If `n` is
// larger than the initial size, new elements are value-initialized.
void resize(size_type n);
// Overload of InlinedVector::resize() to resize the inlined vector to contain
// `n` elements. If `n` is larger than the current size, enough copies of
// `elem` are appended to increase its size to `n`.
void resize(size_type n, const value_type& elem);
// InlinedVector::begin()
//
// Returns an iterator to the beginning of the inlined vector.
iterator begin() noexcept { return data(); }
// Overload of InlinedVector::begin() for returning a const iterator to the
// beginning of the inlined vector.
const_iterator begin() const noexcept { return data(); }
// InlinedVector::cbegin()
//
// Returns a const iterator to the beginning of the inlined vector.
const_iterator cbegin() const noexcept { return begin(); }
// InlinedVector::end()
//
// Returns an iterator to the end of the inlined vector.
iterator end() noexcept { return data() + size(); }
// Overload of InlinedVector::end() for returning a const iterator to the end
// of the inlined vector.
const_iterator end() const noexcept { return data() + size(); }
// InlinedVector::cend()
//
// Returns a const iterator to the end of the inlined vector.
const_iterator cend() const noexcept { return end(); }
// InlinedVector::rbegin()
//
// Returns a reverse iterator from the end of the inlined vector.
reverse_iterator rbegin() noexcept { return reverse_iterator(end()); }
// Overload of InlinedVector::rbegin() for returning a const reverse iterator
// from the end of the inlined vector.
const_reverse_iterator rbegin() const noexcept {
return const_reverse_iterator(end());
}
// InlinedVector::crbegin()
//
// Returns a const reverse iterator from the end of the inlined vector.
const_reverse_iterator crbegin() const noexcept { return rbegin(); }
// InlinedVector::rend()
//
// Returns a reverse iterator from the beginning of the inlined vector.
reverse_iterator rend() noexcept { return reverse_iterator(begin()); }
// Overload of InlinedVector::rend() for returning a const reverse iterator
// from the beginning of the inlined vector.
const_reverse_iterator rend() const noexcept {
return const_reverse_iterator(begin());
}
// InlinedVector::crend()
//
// Returns a reverse iterator from the beginning of the inlined vector.
const_reverse_iterator crend() const noexcept { return rend(); }
// InlinedVector::emplace()
//
// Constructs and inserts an object to the inlined vector at the given
// `position`, returning an iterator pointing to the newly emplaced element.
template <typename... Args>
iterator emplace(const_iterator position, Args&&... args);
// InlinedVector::insert()
//
// Inserts an element of the specified value at `position`, returning an
// iterator pointing to the newly inserted element.
iterator insert(const_iterator position, const value_type& v) {
return emplace(position, v);
}
// Overload of InlinedVector::insert() for inserting an element of the
// specified rvalue, returning an iterator pointing to the newly inserted
// element.
iterator insert(const_iterator position, value_type&& v) {
return emplace(position, std::move(v));
}
// Overload of InlinedVector::insert() for inserting `n` elements of the
// specified value at `position`, returning an iterator pointing to the first
// of the newly inserted elements.
iterator insert(const_iterator position, size_type n, const value_type& v) {
return InsertWithCount(position, n, v);
}
// Overload of `InlinedVector::insert()` to disambiguate the two
// three-argument overloads of `insert()`, returning an iterator pointing to
// the first of the newly inserted elements.
template <typename InputIterator,
typename = typename std::enable_if<std::is_convertible<
typename std::iterator_traits<InputIterator>::iterator_category,
std::input_iterator_tag>::value>::type>
iterator insert(const_iterator position, InputIterator first,
InputIterator last) {
using IterType =
typename std::iterator_traits<InputIterator>::iterator_category;
return InsertWithRange(position, first, last, IterType());
}
// Overload of InlinedVector::insert() for inserting a list of elements at
// `position`, returning an iterator pointing to the first of the newly
// inserted elements.
iterator insert(const_iterator position,
std::initializer_list<value_type> init) {
return insert(position, init.begin(), init.end());
}
// InlinedVector::erase()
//
// Erases the element at `position` of the inlined vector, returning an
// iterator pointing to the following element or the container's end if the
// last element was erased.
iterator erase(const_iterator position) {
assert(position >= begin());
assert(position < end());
iterator pos = const_cast<iterator>(position);
std::move(pos + 1, end(), pos);
pop_back();
return pos;
}
// Overload of InlinedVector::erase() for erasing all elements in the
// iteraror range [first, last) in the inlined vector, returning an iterator
// pointing to the first element following the range erased, or the
// container's end if range included the container's last element.
iterator erase(const_iterator first, const_iterator last);
// InlinedVector::reserve()
//
// Enlarges the underlying representation of the inlined vector so it can hold
// at least `n` elements. This method does not change `size()` or the actual
// contents of the vector.
//
// Note that if `n` does not exceed the inlined vector's initial size `N`,
// `reserve()` will have no effect; if it does exceed its initial size,
// `reserve()` will trigger an initial allocation and move the inlined vector
// onto the heap. If the vector already exists on the heap and the requested
// size exceeds it, a reallocation will be performed.
void reserve(size_type n) {
if (n > capacity()) {
// Make room for new elements
EnlargeBy(n - size());
}
}
// InlinedVector::shrink_to_fit()
//
// Reduces memory usage by freeing unused memory.
// After this call `capacity()` will be equal to `max(N, size())`.
//
// If `size() <= N` and the elements are currently stored on the heap, they
// will be moved to the inlined storage and the heap memory deallocated.
// If `size() > N` and `size() < capacity()` the elements will be moved to
// a reallocated storage on heap.
void shrink_to_fit() {
const auto s = size();
if (!allocated() || s == capacity()) {
// There's nothing to deallocate.
return;
}
if (s <= N) {
// 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.
auto temp = std::move(*this);
assign(std::make_move_iterator(temp.begin()),
std::make_move_iterator(temp.end()));
return;
}
// Reallocate storage and move elements.
// We can't simply use the same approach as above, because assign() would
// call into reserve() internally and reserve larger capacity than we need.
Allocation new_allocation(allocator(), s);
UninitializedCopy(std::make_move_iterator(allocated_space()),
std::make_move_iterator(allocated_space() + s),
new_allocation.buffer());
ResetAllocation(new_allocation, s);
}
// InlinedVector::swap()
//
// Swaps the contents of this inlined vector with the contents of `other`.
void swap(InlinedVector& other);
// InlinedVector::get_allocator()
//
// Returns the allocator of this inlined vector.
allocator_type get_allocator() const { return allocator(); }
private:
static_assert(N > 0, "inlined vector with nonpositive size");
// It holds whether the vector is allocated or not in the lowest bit.
// The size is held in the high bits:
// size_ = (size << 1) | is_allocated;
class Tag {
public:
Tag() : size_(0) {}
size_type size() const { return size_ >> 1; }
void add_size(size_type n) { size_ += n << 1; }
void set_inline_size(size_type n) { size_ = n << 1; }
void set_allocated_size(size_type n) { size_ = (n << 1) | 1; }
bool allocated() const { return size_ & 1; }
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 of it for free.
class AllocatorAndTag : private allocator_type {
public:
explicit AllocatorAndTag(const allocator_type& a, Tag t = Tag())
: allocator_type(a), tag_(t) {
}
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, // NOLINT(runtime/references)
size_type capacity)
: capacity_(capacity),
buffer_(AllocatorTraits::allocate(a, capacity_)) {}
void Dealloc(allocator_type& a) { // NOLINT(runtime/references)
AllocatorTraits::deallocate(a, buffer(), capacity());
}
size_type capacity() const { return capacity_; }
const value_type* buffer() const { return buffer_; }
value_type* buffer() { return buffer_; }
private:
size_type capacity_;
value_type* buffer_;
};
const Tag& tag() const { return allocator_and_tag_.tag(); }
Tag& tag() { return allocator_and_tag_.tag(); }
Allocation& allocation() {
return reinterpret_cast<Allocation&>(rep_.allocation_storage.allocation);
}
const Allocation& allocation() const {
return reinterpret_cast<const Allocation&>(
rep_.allocation_storage.allocation);
}
void init_allocation(const Allocation& allocation) {
new (&rep_.allocation_storage.allocation) Allocation(allocation);
}
value_type* inlined_space() {
return reinterpret_cast<value_type*>(&rep_.inlined_storage.inlined);
}
const value_type* inlined_space() const {
return reinterpret_cast<const value_type*>(&rep_.inlined_storage.inlined);
}
value_type* allocated_space() {
return allocation().buffer();
}
const value_type* allocated_space() const {
return allocation().buffer();
}
const allocator_type& allocator() const {
return allocator_and_tag_.allocator();
}
allocator_type& allocator() {
return allocator_and_tag_.allocator();
}
bool allocated() const { return tag().allocated(); }
// Enlarge the underlying representation so we can store size_ + delta elems.
// The size is not changed, and any newly added memory is not initialized.
void EnlargeBy(size_type delta);
// Shift all elements from position to end() n places to the right.
// If the vector needs to be enlarged, memory will be allocated.
// Returns iterators pointing to the start of the previously-initialized
// portion and the start of the uninitialized portion of the created gap.
// The number of initialized spots is pair.second - pair.first;
// the number of raw spots is n - (pair.second - pair.first).
//
// Updates the size of the InlinedVector internally.
std::pair<iterator, iterator> ShiftRight(const_iterator position,
size_type n);
void ResetAllocation(Allocation new_allocation, size_type new_size) {
if (allocated()) {
Destroy(allocated_space(), allocated_space() + size());
assert(begin() == allocated_space());
allocation().Dealloc(allocator());
allocation() = new_allocation;
} else {
Destroy(inlined_space(), inlined_space() + size());
init_allocation(new_allocation); // bug: only init once
}
tag().set_allocated_size(new_size);
}
template <typename... Args>
value_type& GrowAndEmplaceBack(Args&&... args) {
assert(size() == capacity());
const size_type s = size();
Allocation new_allocation(allocator(), 2 * capacity());
value_type& new_element =
Construct(new_allocation.buffer() + s, std::forward<Args>(args)...);
UninitializedCopy(std::make_move_iterator(data()),
std::make_move_iterator(data() + s),
new_allocation.buffer());
ResetAllocation(new_allocation, s + 1);
return new_element;
}
void InitAssign(size_type n);
void InitAssign(size_type n, const value_type& t);
template <typename... Args>
value_type& Construct(pointer p, Args&&... args) {
AllocatorTraits::construct(allocator(), p, std::forward<Args>(args)...);
return *p;
}
template <typename Iter>
void UninitializedCopy(Iter src, Iter src_last, value_type* dst) {
for (; src != src_last; ++dst, ++src) Construct(dst, *src);
}
template <typename... Args>
void UninitializedFill(value_type* dst, value_type* dst_last,
const Args&... args) {
for (; dst != dst_last; ++dst) Construct(dst, args...);
}
// Destroy [ptr, ptr_last) in place.
void Destroy(value_type* ptr, value_type* ptr_last);
template <typename Iter>
void AppendRange(Iter first, Iter last, std::input_iterator_tag) {
std::copy(first, last, std::back_inserter(*this));
}
// Faster path for forward iterators.
template <typename Iter>
void AppendRange(Iter first, Iter last, std::forward_iterator_tag);
template <typename Iter>
void AppendRange(Iter first, Iter last) {
using IterTag = typename std::iterator_traits<Iter>::iterator_category;
AppendRange(first, last, IterTag());
}
template <typename Iter>
void AssignRange(Iter first, Iter last, std::input_iterator_tag);
// Faster path for forward iterators.
template <typename Iter>
void AssignRange(Iter first, Iter last, std::forward_iterator_tag);
template <typename Iter>
void AssignRange(Iter first, Iter last) {
using IterTag = typename std::iterator_traits<Iter>::iterator_category;
AssignRange(first, last, IterTag());
}
iterator InsertWithCount(const_iterator position, size_type n,
const value_type& v);
template <typename InputIter>
iterator InsertWithRange(const_iterator position, InputIter first,
InputIter last, std::input_iterator_tag);
template <typename ForwardIter>
iterator InsertWithRange(const_iterator position, ForwardIter first,
ForwardIter last, std::forward_iterator_tag);
AllocatorAndTag allocator_and_tag_;
// Either the inlined or allocated representation
union Rep {
// Use struct to perform indirection that solves a bizarre compilation
// error on Visual Studio (all known versions).
struct {
typename std::aligned_storage<sizeof(value_type),
alignof(value_type)>::type inlined[N];
} inlined_storage;
struct {
typename std::aligned_storage<sizeof(Allocation),
alignof(Allocation)>::type allocation;
} allocation_storage;
} rep_;
};
// -----------------------------------------------------------------------------
// InlinedVector Non-Member Functions
// -----------------------------------------------------------------------------
// swap()
//
// Swaps the contents of two inlined vectors. This convenience function
// simply calls InlinedVector::swap(other_inlined_vector).
template <typename T, size_t N, typename A>
void swap(InlinedVector<T, N, A>& a,
InlinedVector<T, N, A>& b) noexcept(noexcept(a.swap(b))) {
a.swap(b);
}
// operator==()
//
// Tests the equivalency of the contents of two inlined vectors.
template <typename T, size_t N, typename A>
bool operator==(const InlinedVector<T, N, A>& a,
const InlinedVector<T, N, A>& b) {
return absl::equal(a.begin(), a.end(), b.begin(), b.end());
}
// operator!=()
//
// Tests the inequality of the contents of two inlined vectors.
template <typename T, size_t N, typename A>
bool operator!=(const InlinedVector<T, N, A>& a,
const InlinedVector<T, N, A>& b) {
return !(a == b);
}
// operator<()
//
// Tests whether the contents of one inlined vector are less than the contents
// of another through a lexicographical comparison operation.
template <typename T, size_t N, typename A>
bool operator<(const InlinedVector<T, N, A>& a,
const InlinedVector<T, N, A>& b) {
return std::lexicographical_compare(a.begin(), a.end(), b.begin(), b.end());
}
// operator>()
//
// Tests whether the contents of one inlined vector are greater than the
// contents of another through a lexicographical comparison operation.
template <typename T, size_t N, typename A>
bool operator>(const InlinedVector<T, N, A>& a,
const InlinedVector<T, N, A>& b) {
return b < a;
}
// operator<=()
//
// Tests whether the contents of one inlined vector are less than or equal to
// the contents of another through a lexicographical comparison operation.
template <typename T, size_t N, typename A>
bool operator<=(const InlinedVector<T, N, A>& a,
const InlinedVector<T, N, A>& b) {
return !(b < a);
}
// operator>=()
//
// Tests whether the contents of one inlined vector are greater than or equal to
// the contents of another through a lexicographical comparison operation.
template <typename T, size_t N, typename A>
bool operator>=(const InlinedVector<T, N, A>& a,
const InlinedVector<T, N, A>& b) {
return !(a < b);
}
// -----------------------------------------------------------------------------
// Implementation of InlinedVector
// -----------------------------------------------------------------------------
//
// Do not depend on any implementation details below this line.
template <typename T, size_t N, typename A>
InlinedVector<T, N, A>::InlinedVector(const InlinedVector& v)
: allocator_and_tag_(v.allocator()) {
reserve(v.size());
if (allocated()) {
UninitializedCopy(v.begin(), v.end(), allocated_space());
tag().set_allocated_size(v.size());
} else {
UninitializedCopy(v.begin(), v.end(), inlined_space());
tag().set_inline_size(v.size());
}
}
template <typename T, size_t N, typename A>
InlinedVector<T, N, A>::InlinedVector(const InlinedVector& v,
const allocator_type& alloc)
: allocator_and_tag_(alloc) {
reserve(v.size());
if (allocated()) {
UninitializedCopy(v.begin(), v.end(), allocated_space());
tag().set_allocated_size(v.size());
} else {
UninitializedCopy(v.begin(), v.end(), inlined_space());
tag().set_inline_size(v.size());
}
}
template <typename T, size_t N, typename A>
InlinedVector<T, N, A>::InlinedVector(InlinedVector&& v) noexcept(
absl::allocator_is_nothrow<allocator_type>::value ||
std::is_nothrow_move_constructible<value_type>::value)
: allocator_and_tag_(v.allocator_and_tag_) {
if (v.allocated()) {
// We can just steal the underlying buffer from the source.
// That leaves the source empty, so we clear its size.
init_allocation(v.allocation());
v.tag() = Tag();
} else {
UninitializedCopy(std::make_move_iterator(v.inlined_space()),
std::make_move_iterator(v.inlined_space() + v.size()),
inlined_space());
}
}
template <typename T, size_t N, typename A>
InlinedVector<T, N, A>::InlinedVector(
InlinedVector&& v,
const allocator_type&
alloc) noexcept(absl::allocator_is_nothrow<allocator_type>::value)
: allocator_and_tag_(alloc) {
if (v.allocated()) {
if (alloc == v.allocator()) {
// We can just steal the allocation from the source.
tag() = v.tag();
init_allocation(v.allocation());
v.tag() = Tag();
} else {
// We need to use our own allocator
reserve(v.size());
UninitializedCopy(std::make_move_iterator(v.begin()),
std::make_move_iterator(v.end()), allocated_space());
tag().set_allocated_size(v.size());
}
} else {
UninitializedCopy(std::make_move_iterator(v.inlined_space()),
std::make_move_iterator(v.inlined_space() + v.size()),
inlined_space());
tag().set_inline_size(v.size());
}
}
template <typename T, size_t N, typename A>
void InlinedVector<T, N, A>::InitAssign(size_type n, const value_type& t) {
if (n > static_cast<size_type>(N)) {
Allocation new_allocation(allocator(), n);
init_allocation(new_allocation);
UninitializedFill(allocated_space(), allocated_space() + n, t);
tag().set_allocated_size(n);
} else {
UninitializedFill(inlined_space(), inlined_space() + n, t);
tag().set_inline_size(n);
}
}
template <typename T, size_t N, typename A>
void InlinedVector<T, N, A>::InitAssign(size_type n) {
if (n > static_cast<size_type>(N)) {
Allocation new_allocation(allocator(), n);
init_allocation(new_allocation);
UninitializedFill(allocated_space(), allocated_space() + n);
tag().set_allocated_size(n);
} else {
UninitializedFill(inlined_space(), inlined_space() + n);
tag().set_inline_size(n);
}
}
template <typename T, size_t N, typename A>
void InlinedVector<T, N, A>::resize(size_type n) {
size_type s = size();
if (n < s) {
erase(begin() + n, end());
return;
}
reserve(n);
assert(capacity() >= n);
// Fill new space with elements constructed in-place.
if (allocated()) {
UninitializedFill(allocated_space() + s, allocated_space() + n);
tag().set_allocated_size(n);
} else {
UninitializedFill(inlined_space() + s, inlined_space() + n);
tag().set_inline_size(n);
}
}
template <typename T, size_t N, typename A>
void InlinedVector<T, N, A>::resize(size_type n, const value_type& elem) {
size_type s = size();
if (n < s) {
erase(begin() + n, end());
return;
}
reserve(n);
assert(capacity() >= n);
// Fill new space with copies of 'elem'.
if (allocated()) {
UninitializedFill(allocated_space() + s, allocated_space() + n, elem);
tag().set_allocated_size(n);
} else {
UninitializedFill(inlined_space() + s, inlined_space() + n, elem);
tag().set_inline_size(n);
}
}
template <typename T, size_t N, typename A>
template <typename... Args>
typename InlinedVector<T, N, A>::iterator InlinedVector<T, N, A>::emplace(
const_iterator position, Args&&... args) {
assert(position >= begin());
assert(position <= end());
if (position == end()) {
emplace_back(std::forward<Args>(args)...);
return end() - 1;
}
T new_t = T(std::forward<Args>(args)...);
auto range = ShiftRight(position, 1);
if (range.first == range.second) {
// constructing into uninitialized memory
Construct(range.first, std::move(new_t));
} else {
// assigning into moved-from object
*range.first = T(std::move(new_t));
}
return range.first;
}
template <typename T, size_t N, typename A>
typename InlinedVector<T, N, A>::iterator InlinedVector<T, N, A>::erase(
const_iterator first, const_iterator last) {
assert(begin() <= first);
assert(first <= last);
assert(last <= end());
iterator range_start = const_cast<iterator>(first);
iterator range_end = const_cast<iterator>(last);
size_type s = size();
ptrdiff_t erase_gap = std::distance(range_start, range_end);
if (erase_gap > 0) {
pointer space;
if (allocated()) {
space = allocated_space();
tag().set_allocated_size(s - erase_gap);
} else {
space = inlined_space();
tag().set_inline_size(s - erase_gap);
}
std::move(range_end, space + s, range_start);
Destroy(space + s - erase_gap, space + s);
}
return range_start;
}
template <typename T, size_t N, typename A>
void InlinedVector<T, N, A>::swap(InlinedVector& other) {
using std::swap; // Augment ADL with std::swap.
if (&other == this) {
return;
}
if (allocated() && other.allocated()) {
// Both out of line, so just swap the tag, allocation, and allocator.
swap(tag(), other.tag());
swap(allocation(), other.allocation());
swap(allocator(), other.allocator());
return;
}
if (!allocated() && !other.allocated()) {
// Both inlined: swap up to smaller size, then move remaining elements.
InlinedVector* a = this;
InlinedVector* b = &other;
if (size() < other.size()) {
swap(a, b);
}
const size_type a_size = a->size();
const size_type b_size = b->size();
assert(a_size >= b_size);
// 'a' is larger. Swap the elements up to the smaller array size.
std::swap_ranges(a->inlined_space(),
a->inlined_space() + b_size,
b->inlined_space());
// Move the remaining elements: A[b_size,a_size) -> B[b_size,a_size)
b->UninitializedCopy(a->inlined_space() + b_size,
a->inlined_space() + a_size,
b->inlined_space() + b_size);
a->Destroy(a->inlined_space() + b_size, a->inlined_space() + a_size);
swap(a->tag(), b->tag());
swap(a->allocator(), b->allocator());
assert(b->size() == a_size);
assert(a->size() == b_size);
return;
}
// One is out of line, one is inline.
// We first move the elements from the inlined vector into the
// inlined space in the other vector. We then put the other vector's
// pointer/capacity into the originally inlined vector and swap
// the tags.
InlinedVector* a = this;
InlinedVector* b = &other;
if (a->allocated()) {
swap(a, b);
}
assert(!a->allocated());
assert(b->allocated());
const size_type a_size = a->size();
const size_type b_size = b->size();
// In an optimized build, b_size would be unused.
(void)b_size;
// Made Local copies of size(), don't need tag() accurate anymore
swap(a->tag(), b->tag());
// Copy b_allocation out before b's union gets clobbered by inline_space.
Allocation b_allocation = b->allocation();
b->UninitializedCopy(a->inlined_space(), a->inlined_space() + a_size,
b->inlined_space());
a->Destroy(a->inlined_space(), a->inlined_space() + a_size);
a->allocation() = b_allocation;
if (a->allocator() != b->allocator()) {
swap(a->allocator(), b->allocator());
}
assert(b->size() == a_size);
assert(a->size() == b_size);
}
template <typename T, size_t N, typename A>
void InlinedVector<T, N, A>::EnlargeBy(size_type delta) {
const size_type s = size();
assert(s <= capacity());
size_type target = std::max(static_cast<size_type>(N), s + delta);
// Compute new capacity by repeatedly doubling current capacity
// TODO(psrc): Check and avoid overflow?
size_type new_capacity = capacity();
while (new_capacity < target) {
new_capacity <<= 1;
}
Allocation new_allocation(allocator(), new_capacity);
UninitializedCopy(std::make_move_iterator(data()),
std::make_move_iterator(data() + s),
new_allocation.buffer());
ResetAllocation(new_allocation, s);
}
template <typename T, size_t N, typename A>
auto InlinedVector<T, N, A>::ShiftRight(const_iterator position, size_type n)
-> std::pair<iterator, iterator> {
iterator start_used = const_cast<iterator>(position);
iterator start_raw = const_cast<iterator>(position);
size_type s = size();
size_type required_size = s + n;
if (required_size > capacity()) {
// Compute new capacity by repeatedly doubling current capacity
size_type new_capacity = capacity();
while (new_capacity < required_size) {
new_capacity <<= 1;
}
// Move everyone into the new allocation, leaving a gap of n for the
// requested shift.
Allocation new_allocation(allocator(), new_capacity);
size_type index = position - begin();
UninitializedCopy(std::make_move_iterator(data()),
std::make_move_iterator(data() + index),
new_allocation.buffer());
UninitializedCopy(std::make_move_iterator(data() + index),
std::make_move_iterator(data() + s),
new_allocation.buffer() + index + n);
ResetAllocation(new_allocation, s);
// New allocation means our iterator is invalid, so we'll recalculate.
// Since the entire gap is in new space, there's no used space to reuse.
start_raw = begin() + index;
start_used = start_raw;
} else {
// If we had enough space, it's a two-part move. Elements going into
// previously-unoccupied space need an UninitializedCopy. Elements
// going into a previously-occupied space are just a move.
iterator pos = const_cast<iterator>(position);
iterator raw_space = end();
size_type slots_in_used_space = raw_space - pos;
size_type new_elements_in_used_space = std::min(n, slots_in_used_space);
size_type new_elements_in_raw_space = n - new_elements_in_used_space;
size_type old_elements_in_used_space =
slots_in_used_space - new_elements_in_used_space;
UninitializedCopy(std::make_move_iterator(pos + old_elements_in_used_space),
std::make_move_iterator(raw_space),
raw_space + new_elements_in_raw_space);
std::move_backward(pos, pos + old_elements_in_used_space, raw_space);
// If the gap is entirely in raw space, the used space starts where the raw
// space starts, leaving no elements in used space. If the gap is entirely
// in used space, the raw space starts at the end of the gap, leaving all
// elements accounted for within the used space.
start_used = pos;
start_raw = pos + new_elements_in_used_space;
}
tag().add_size(n);
return std::make_pair(start_used, start_raw);
}
template <typename T, size_t N, typename A>
void InlinedVector<T, N, A>::Destroy(value_type* ptr, value_type* ptr_last) {
for (value_type* p = ptr; p != ptr_last; ++p) {
AllocatorTraits::destroy(allocator(), p);
}
// 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.
#ifndef NDEBUG
if (ptr != ptr_last) {
memset(reinterpret_cast<void*>(ptr), 0xab,
sizeof(*ptr) * (ptr_last - ptr));
}
#endif
}
template <typename T, size_t N, typename A>
template <typename Iter>
void InlinedVector<T, N, A>::AppendRange(Iter first, Iter last,
std::forward_iterator_tag) {
using Length = typename std::iterator_traits<Iter>::difference_type;
Length length = std::distance(first, last);
reserve(size() + length);
if (allocated()) {
UninitializedCopy(first, last, allocated_space() + size());
tag().set_allocated_size(size() + length);
} else {
UninitializedCopy(first, last, inlined_space() + size());
tag().set_inline_size(size() + length);
}
}
template <typename T, size_t N, typename A>
template <typename Iter>
void InlinedVector<T, N, A>::AssignRange(Iter first, Iter last,
std::input_iterator_tag) {
// Optimized to avoid reallocation.
// Prefer reassignment to copy construction for elements.
iterator out = begin();
for ( ; first != last && out != end(); ++first, ++out)
*out = *first;
erase(out, end());
std::copy(first, last, std::back_inserter(*this));
}
template <typename T, size_t N, typename A>
template <typename Iter>
void InlinedVector<T, N, A>::AssignRange(Iter first, Iter last,
std::forward_iterator_tag) {
using Length = typename std::iterator_traits<Iter>::difference_type;
Length length = std::distance(first, last);
// Prefer reassignment to copy construction for elements.
if (static_cast<size_type>(length) <= size()) {
erase(std::copy(first, last, begin()), end());
return;
}
reserve(length);
iterator out = begin();
for (; out != end(); ++first, ++out) *out = *first;
if (allocated()) {
UninitializedCopy(first, last, out);
tag().set_allocated_size(length);
} else {
UninitializedCopy(first, last, out);
tag().set_inline_size(length);
}
}
template <typename T, size_t N, typename A>
auto InlinedVector<T, N, A>::InsertWithCount(const_iterator position,
size_type n, const value_type& v)
-> iterator {
assert(position >= begin() && position <= end());
if (n == 0) return const_cast<iterator>(position);
value_type copy = v;
std::pair<iterator, iterator> it_pair = ShiftRight(position, n);
std::fill(it_pair.first, it_pair.second, copy);
UninitializedFill(it_pair.second, it_pair.first + n, copy);
return it_pair.first;
}
template <typename T, size_t N, typename A>
template <typename InputIter>
auto InlinedVector<T, N, A>::InsertWithRange(const_iterator position,
InputIter first, InputIter last,
std::input_iterator_tag)
-> iterator {
assert(position >= begin() && position <= end());
size_type index = position - cbegin();
size_type i = index;
while (first != last) insert(begin() + i++, *first++);
return begin() + index;
}
// Overload of InlinedVector::InsertWithRange()
template <typename T, size_t N, typename A>
template <typename ForwardIter>
auto InlinedVector<T, N, A>::InsertWithRange(const_iterator position,
ForwardIter first,
ForwardIter last,
std::forward_iterator_tag)
-> iterator {
assert(position >= begin() && position <= end());
if (first == last) {
return const_cast<iterator>(position);
}
using Length = typename std::iterator_traits<ForwardIter>::difference_type;
Length n = std::distance(first, last);
std::pair<iterator, iterator> it_pair = ShiftRight(position, n);
size_type used_spots = it_pair.second - it_pair.first;
ForwardIter open_spot = std::next(first, used_spots);
std::copy(first, open_spot, it_pair.first);
UninitializedCopy(open_spot, last, it_pair.second);
return it_pair.first;
}
} // namespace absl
#endif // ABSL_CONTAINER_INLINED_VECTOR_H_