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/*
* Copyright (c) Facebook, Inc. and its affiliates.
*
* 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.
*/
/*
* For high-level documentation and usage examples see
* folly/docs/small_vector.md
*
* @author Jordan DeLong <delong.j@fb.com>
*/
#pragma once
#include <algorithm>
#include <cassert>
#include <cstdlib>
#include <cstring>
#include <iterator>
#include <stdexcept>
#include <type_traits>
#include <utility>
#include <boost/mpl/count.hpp>
#include <boost/mpl/empty.hpp>
#include <boost/mpl/eval_if.hpp>
#include <boost/mpl/filter_view.hpp>
#include <boost/mpl/front.hpp>
#include <boost/mpl/identity.hpp>
#include <boost/mpl/if.hpp>
#include <boost/mpl/placeholders.hpp>
#include <boost/mpl/size.hpp>
#include <boost/mpl/vector.hpp>
#include <boost/operators.hpp>
#include <folly/ConstexprMath.h>
#include <folly/FormatTraits.h>
#include <folly/Likely.h>
#include <folly/Portability.h>
#include <folly/ScopeGuard.h>
#include <folly/Traits.h>
#include <folly/lang/Assume.h>
#include <folly/lang/Exception.h>
#include <folly/memory/Malloc.h>
#include <folly/portability/Malloc.h>
#if (FOLLY_X64 || FOLLY_PPC64)
#define FOLLY_SV_PACK_ATTR FOLLY_PACK_ATTR
#define FOLLY_SV_PACK_PUSH FOLLY_PACK_PUSH
#define FOLLY_SV_PACK_POP FOLLY_PACK_POP
#else
#define FOLLY_SV_PACK_ATTR
#define FOLLY_SV_PACK_PUSH
#define FOLLY_SV_PACK_POP
#endif
// Ignore shadowing warnings within this file, so includers can use -Wshadow.
FOLLY_PUSH_WARNING
FOLLY_GNU_DISABLE_WARNING("-Wshadow")
namespace folly {
//////////////////////////////////////////////////////////////////////
namespace small_vector_policy {
//////////////////////////////////////////////////////////////////////
/*
* A flag which makes us refuse to use the heap at all. If we
* overflow the in situ capacity we throw an exception.
*/
struct NoHeap;
//////////////////////////////////////////////////////////////////////
} // namespace small_vector_policy
//////////////////////////////////////////////////////////////////////
template <class T, std::size_t M, class A, class B, class C>
class small_vector;
//////////////////////////////////////////////////////////////////////
namespace detail {
/*
* Move objects in memory to the right into some uninitialized
* memory, where the region overlaps. Then call create(size_t) for each
* "hole" passing it the offset of the hole from first.
*
* This doesn't just use std::move_backward because move_backward only works
* if all the memory is initialized to type T already.
*
* The create function should return a reference type, to avoid
* extra copies and moves for non-trivial types.
*/
template <class T, class Create>
typename std::enable_if<!folly::is_trivially_copyable<T>::value>::type
moveObjectsRightAndCreate(
T* const first,
T* const lastConstructed,
T* const realLast,
Create&& create) {
if (lastConstructed == realLast) {
return;
}
T* out = realLast;
T* in = lastConstructed;
{
auto rollback = makeGuard([&] {
// We want to make sure the same stuff is uninitialized memory
// if we exit via an exception (this is to make sure we provide
// the basic exception safety guarantee for insert functions).
if (out < lastConstructed) {
out = lastConstructed - 1;
}
for (auto it = out + 1; it != realLast; ++it) {
it->~T();
}
});
// Decrement the pointers only when it is known that the resulting pointer
// is within the boundaries of the object. Decrementing past the beginning
// of the object is UB. Note that this is asymmetric wrt forward iteration,
// as past-the-end pointers are explicitly allowed.
for (; in != first && out > lastConstructed;) {
// Out must be decremented before an exception can be thrown so that
// the rollback guard knows where to start.
--out;
new (out) T(std::move(*(--in)));
}
for (; in != first;) {
--out;
*out = std::move(*(--in));
}
for (; out > lastConstructed;) {
--out;
new (out) T(create(out - first));
}
for (; out != first;) {
--out;
*out = create(out - first);
}
rollback.dismiss();
}
}
// Specialization for trivially copyable types. The call to
// std::move_backward here will just turn into a memmove.
// This must only be used with trivially copyable types because some of the
// memory may be uninitialized, and std::move_backward() won't work when it
// can't memmove().
template <class T, class Create>
typename std::enable_if<folly::is_trivially_copyable<T>::value>::type
moveObjectsRightAndCreate(
T* const first,
T* const lastConstructed,
T* const realLast,
Create&& create) {
std::move_backward(first, lastConstructed, realLast);
T* const end = first - 1;
T* out = first + (realLast - lastConstructed) - 1;
for (; out != end; --out) {
*out = create(out - first);
}
}
/*
* Populate a region of memory using `op' to construct elements. If
* anything throws, undo what we did.
*/
template <class T, class Function>
void populateMemForward(T* mem, std::size_t n, Function const& op) {
std::size_t idx = 0;
{
auto rollback = makeGuard([&] {
for (std::size_t i = 0; i < idx; ++i) {
mem[i].~T();
}
});
for (size_t i = 0; i < n; ++i) {
op(&mem[idx]);
++idx;
}
rollback.dismiss();
}
}
template <class SizeType, bool ShouldUseHeap>
struct IntegralSizePolicyBase {
typedef SizeType InternalSizeType;
IntegralSizePolicyBase() : size_(0) {}
protected:
static constexpr std::size_t policyMaxSize() {
return SizeType(~kExternMask);
}
std::size_t doSize() const {
return size_ & ~kExternMask;
}
std::size_t isExtern() const {
return kExternMask & size_;
}
void setExtern(bool b) {
if (b) {
size_ |= kExternMask;
} else {
size_ &= ~kExternMask;
}
}
void setSize(std::size_t sz) {
assert(sz <= policyMaxSize());
size_ = (kExternMask & size_) | SizeType(sz);
}
void swapSizePolicy(IntegralSizePolicyBase& o) {
std::swap(size_, o.size_);
}
protected:
static bool constexpr kShouldUseHeap = ShouldUseHeap;
private:
static SizeType constexpr kExternMask =
kShouldUseHeap ? SizeType(1) << (sizeof(SizeType) * 8 - 1) : 0;
SizeType size_;
};
template <class SizeType, bool ShouldUseHeap>
struct IntegralSizePolicy;
template <class SizeType>
struct IntegralSizePolicy<SizeType, true>
: public IntegralSizePolicyBase<SizeType, true> {
public:
/*
* Move a range to a range of uninitialized memory. Assumes the
* ranges don't overlap.
*/
template <class T>
typename std::enable_if<!folly::is_trivially_copyable<T>::value>::type
moveToUninitialized(T* first, T* last, T* out) {
std::size_t idx = 0;
{
auto rollback = makeGuard([&] {
// Even for callers trying to give the strong guarantee
// (e.g. push_back) it's ok to assume here that we don't have to
// move things back and that it was a copy constructor that
// threw: if someone throws from a move constructor the effects
// are unspecified.
for (std::size_t i = 0; i < idx; ++i) {
out[i].~T();
}
});
for (; first != last; ++first, ++idx) {
new (&out[idx]) T(std::move(*first));
}
rollback.dismiss();
}
}
// Specialization for trivially copyable types.
template <class T>
typename std::enable_if<folly::is_trivially_copyable<T>::value>::type
moveToUninitialized(T* first, T* last, T* out) {
std::memmove(
static_cast<void*>(out),
static_cast<void const*>(first),
(last - first) * sizeof *first);
}
/*
* Move a range to a range of uninitialized memory. Assumes the
* ranges don't overlap. Inserts an element at out + pos using
* emplaceFunc(). out will contain (end - begin) + 1 elements on success and
* none on failure. If emplaceFunc() throws [begin, end) is unmodified.
*/
template <class T, class EmplaceFunc>
void moveToUninitializedEmplace(
T* begin,
T* end,
T* out,
SizeType pos,
EmplaceFunc&& emplaceFunc) {
// Must be called first so that if it throws [begin, end) is unmodified.
// We have to support the strong exception guarantee for emplace_back().
emplaceFunc(out + pos);
// move old elements to the left of the new one
{
auto rollback = makeGuard([&] { //
out[pos].~T();
});
this->moveToUninitialized(begin, begin + pos, out);
rollback.dismiss();
}
// move old elements to the right of the new one
{
auto rollback = makeGuard([&] {
for (SizeType i = 0; i <= pos; ++i) {
out[i].~T();
}
});
if (begin + pos < end) {
this->moveToUninitialized(begin + pos, end, out + pos + 1);
}
rollback.dismiss();
}
}
};
template <class SizeType>
struct IntegralSizePolicy<SizeType, false>
: public IntegralSizePolicyBase<SizeType, false> {
public:
template <class T>
void moveToUninitialized(T* /*first*/, T* /*last*/, T* /*out*/) {
assume_unreachable();
}
template <class T, class EmplaceFunc>
void moveToUninitializedEmplace(
T* /* begin */,
T* /* end */,
T* /* out */,
SizeType /* pos */,
EmplaceFunc&& /* emplaceFunc */) {
assume_unreachable();
}
};
/*
* If you're just trying to use this class, ignore everything about
* this next small_vector_base class thing.
*
* The purpose of this junk is to minimize sizeof(small_vector<>)
* and allow specifying the template parameters in whatever order is
* convenient for the user. There's a few extra steps here to try
* to keep the error messages at least semi-reasonable.
*
* Apologies for all the black magic.
*/
namespace mpl = boost::mpl;
template <
class Value,
std::size_t RequestedMaxInline,
class InPolicyA,
class InPolicyB,
class InPolicyC>
struct small_vector_base {
typedef mpl::vector<InPolicyA, InPolicyB, InPolicyC> PolicyList;
/*
* Determine the size type
*/
typedef typename mpl::filter_view<
PolicyList,
std::is_integral<mpl::placeholders::_1>>::type Integrals;
typedef typename mpl::eval_if<
mpl::empty<Integrals>,
mpl::identity<std::size_t>,
mpl::front<Integrals>>::type SizeType;
static_assert(
std::is_unsigned<SizeType>::value,
"Size type should be an unsigned integral type");
static_assert(
mpl::size<Integrals>::value == 0 || mpl::size<Integrals>::value == 1,
"Multiple size types specified in small_vector<>");
/*
* Determine whether we should allow spilling to the heap or not.
*/
typedef typename mpl::count<PolicyList, small_vector_policy::NoHeap>::type
HasNoHeap;
static_assert(
HasNoHeap::value == 0 || HasNoHeap::value == 1,
"Multiple copies of small_vector_policy::NoHeap "
"supplied; this is probably a mistake");
/*
* Make the real policy base classes.
*/
typedef IntegralSizePolicy<SizeType, !HasNoHeap::value> ActualSizePolicy;
/*
* Now inherit from them all. This is done in such a convoluted
* way to make sure we get the empty base optimizaton on all these
* types to keep sizeof(small_vector<>) minimal.
*/
typedef boost::totally_ordered1<
small_vector<Value, RequestedMaxInline, InPolicyA, InPolicyB, InPolicyC>,
ActualSizePolicy>
type;
};
template <class T>
T* pointerFlagSet(T* p) {
return reinterpret_cast<T*>(reinterpret_cast<uintptr_t>(p) | 1);
}
template <class T>
bool pointerFlagGet(T* p) {
return reinterpret_cast<uintptr_t>(p) & 1;
}
template <class T>
T* pointerFlagClear(T* p) {
return reinterpret_cast<T*>(reinterpret_cast<uintptr_t>(p) & ~uintptr_t(1));
}
inline void* shiftPointer(void* p, size_t sizeBytes) {
return static_cast<char*>(p) + sizeBytes;
}
} // namespace detail
//////////////////////////////////////////////////////////////////////
FOLLY_SV_PACK_PUSH
template <
class Value,
std::size_t RequestedMaxInline = 1,
class PolicyA = void,
class PolicyB = void,
class PolicyC = void>
class small_vector : public detail::small_vector_base<
Value,
RequestedMaxInline,
PolicyA,
PolicyB,
PolicyC>::type {
typedef typename detail::
small_vector_base<Value, RequestedMaxInline, PolicyA, PolicyB, PolicyC>::
type BaseType;
typedef typename BaseType::InternalSizeType InternalSizeType;
/*
* Figure out the max number of elements we should inline. (If
* the user asks for less inlined elements than we can fit unioned
* into our value_type*, we will inline more than they asked.)
*/
static constexpr std::size_t MaxInline{
constexpr_max(sizeof(Value*) / sizeof(Value), RequestedMaxInline)};
public:
typedef std::size_t size_type;
typedef Value value_type;
typedef std::allocator<Value> allocator_type;
typedef value_type& reference;
typedef value_type const& const_reference;
typedef value_type* iterator;
typedef value_type* pointer;
typedef value_type const* const_iterator;
typedef value_type const* const_pointer;
typedef std::ptrdiff_t difference_type;
typedef std::reverse_iterator<iterator> reverse_iterator;
typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
small_vector() = default;
// Allocator is unused here. It is taken in for compatibility with std::vector
// interface, but it will be ignored.
small_vector(const std::allocator<Value>&) {}
small_vector(small_vector const& o) {
auto n = o.size();
makeSize(n);
{
auto rollback = makeGuard([&] {
if (this->isExtern()) {
u.freeHeap();
}
});
std::uninitialized_copy(o.begin(), o.end(), begin());
rollback.dismiss();
}
this->setSize(n);
}
small_vector(small_vector&& o) noexcept(
std::is_nothrow_move_constructible<Value>::value) {
if (o.isExtern()) {
swap(o);
} else {
std::uninitialized_copy(
std::make_move_iterator(o.begin()),
std::make_move_iterator(o.end()),
begin());
this->setSize(o.size());
}
}
small_vector(std::initializer_list<value_type> il) {
constructImpl(il.begin(), il.end(), std::false_type());
}
explicit small_vector(size_type n) {
doConstruct(n, [&](void* p) { new (p) value_type(); });
}
small_vector(size_type n, value_type const& t) {
doConstruct(n, [&](void* p) { new (p) value_type(t); });
}
template <class Arg>
explicit small_vector(Arg arg1, Arg arg2) {
// Forward using std::is_arithmetic to get to the proper
// implementation; this disambiguates between the iterators and
// (size_t, value_type) meaning for this constructor.
constructImpl(arg1, arg2, std::is_arithmetic<Arg>());
}
~small_vector() {
for (auto& t : *this) {
(&t)->~value_type();
}
if (this->isExtern()) {
u.freeHeap();
}
}
small_vector& operator=(small_vector const& o) {
if (FOLLY_LIKELY(this != &o)) {
assign(o.begin(), o.end());
}
return *this;
}
small_vector& operator=(small_vector&& o) {
// TODO: optimization:
// if both are internal, use move assignment where possible
if (FOLLY_LIKELY(this != &o)) {
clear();
swap(o);
}
return *this;
}
bool operator==(small_vector const& o) const {
return size() == o.size() && std::equal(begin(), end(), o.begin());
}
bool operator<(small_vector const& o) const {
return std::lexicographical_compare(begin(), end(), o.begin(), o.end());
}
static constexpr size_type max_size() {
return !BaseType::kShouldUseHeap ? static_cast<size_type>(MaxInline)
: BaseType::policyMaxSize();
}
allocator_type get_allocator() const {
return {};
}
size_type size() const {
return this->doSize();
}
bool empty() const {
return !size();
}
iterator begin() {
return data();
}
iterator end() {
return data() + size();
}
const_iterator begin() const {
return data();
}
const_iterator end() const {
return data() + size();
}
const_iterator cbegin() const {
return begin();
}
const_iterator cend() const {
return end();
}
reverse_iterator rbegin() {
return reverse_iterator(end());
}
reverse_iterator rend() {
return reverse_iterator(begin());
}
const_reverse_iterator rbegin() const {
return const_reverse_iterator(end());
}
const_reverse_iterator rend() const {
return const_reverse_iterator(begin());
}
const_reverse_iterator crbegin() const {
return rbegin();
}
const_reverse_iterator crend() const {
return rend();
}
/*
* Usually one of the simplest functions in a Container-like class
* but a bit more complex here. We have to handle all combinations
* of in-place vs. heap between this and o.
*
* Basic guarantee only. Provides the nothrow guarantee iff our
* value_type has a nothrow move or copy constructor.
*/
void swap(small_vector& o) {
using std::swap; // Allow ADL on swap for our value_type.
if (this->isExtern() && o.isExtern()) {
this->swapSizePolicy(o);
auto thisCapacity = this->capacity();
auto oCapacity = o.capacity();
auto* tmp = u.pdata_.heap_;
u.pdata_.heap_ = o.u.pdata_.heap_;
o.u.pdata_.heap_ = tmp;
this->setCapacity(oCapacity);
o.setCapacity(thisCapacity);
return;
}
if (!this->isExtern() && !o.isExtern()) {
auto& oldSmall = size() < o.size() ? *this : o;
auto& oldLarge = size() < o.size() ? o : *this;
for (size_type i = 0; i < oldSmall.size(); ++i) {
swap(oldSmall[i], oldLarge[i]);
}
size_type i = oldSmall.size();
const size_type ci = i;
{
auto rollback = makeGuard([&] {
oldSmall.setSize(i);
for (; i < oldLarge.size(); ++i) {
oldLarge[i].~value_type();
}
oldLarge.setSize(ci);
});
for (; i < oldLarge.size(); ++i) {
auto addr = oldSmall.begin() + i;
new (addr) value_type(std::move(oldLarge[i]));
oldLarge[i].~value_type();
}
rollback.dismiss();
}
oldSmall.setSize(i);
oldLarge.setSize(ci);
return;
}
// isExtern != o.isExtern()
auto& oldExtern = o.isExtern() ? o : *this;
auto& oldIntern = o.isExtern() ? *this : o;
auto oldExternCapacity = oldExtern.capacity();
auto oldExternHeap = oldExtern.u.pdata_.heap_;
auto buff = oldExtern.u.buffer();
size_type i = 0;
{
auto rollback = makeGuard([&] {
for (size_type kill = 0; kill < i; ++kill) {
buff[kill].~value_type();
}
for (; i < oldIntern.size(); ++i) {
oldIntern[i].~value_type();
}
oldIntern.setSize(0);
oldExtern.u.pdata_.heap_ = oldExternHeap;
oldExtern.setCapacity(oldExternCapacity);
});
for (; i < oldIntern.size(); ++i) {
new (&buff[i]) value_type(std::move(oldIntern[i]));
oldIntern[i].~value_type();
}
rollback.dismiss();
}
oldIntern.u.pdata_.heap_ = oldExternHeap;
this->swapSizePolicy(o);
oldIntern.setCapacity(oldExternCapacity);
}
void resize(size_type sz) {
if (sz < size()) {
erase(begin() + sz, end());
return;
}
makeSize(sz);
detail::populateMemForward(
begin() + size(), sz - size(), [&](void* p) { new (p) value_type(); });
this->setSize(sz);
}
void resize(size_type sz, value_type const& v) {
if (sz < size()) {
erase(begin() + sz, end());
return;
}
makeSize(sz);
detail::populateMemForward(
begin() + size(), sz - size(), [&](void* p) { new (p) value_type(v); });
this->setSize(sz);
}
value_type* data() noexcept {
return this->isExtern() ? u.heap() : u.buffer();
}
value_type const* data() const noexcept {
return this->isExtern() ? u.heap() : u.buffer();
}
template <class... Args>
iterator emplace(const_iterator p, Args&&... args) {
if (p == cend()) {
emplace_back(std::forward<Args>(args)...);
return end() - 1;
}
/*
* We implement emplace at places other than at the back with a
* temporary for exception safety reasons. It is possible to
* avoid having to do this, but it becomes hard to maintain the
* basic exception safety guarantee (unless you respond to a copy
* constructor throwing by clearing the whole vector).
*
* The reason for this is that otherwise you have to destruct an
* element before constructing this one in its place---if the
* constructor throws, you either need a nothrow default
* constructor or a nothrow copy/move to get something back in the
* "gap", and the vector requirements don't guarantee we have any
* of these. Clearing the whole vector is a legal response in
* this situation, but it seems like this implementation is easy
* enough and probably better.
*/
return insert(p, value_type(std::forward<Args>(args)...));
}
void reserve(size_type sz) {
makeSize(sz);
}
size_type capacity() const {
if (this->isExtern()) {
if (u.hasCapacity()) {
return u.getCapacity();
}
return malloc_usable_size(u.pdata_.heap_) / sizeof(value_type);
}
return MaxInline;
}
void shrink_to_fit() {
if (!this->isExtern()) {
return;
}
small_vector tmp(begin(), end());
tmp.swap(*this);
}
template <class... Args>
reference emplace_back(Args&&... args) {
if (capacity() == size()) {
// Any of args may be references into the vector.
// When we are reallocating, we have to be careful to construct the new
// element before modifying the data in the old buffer.
makeSize(
size() + 1,
[&](void* p) { new (p) value_type(std::forward<Args>(args)...); },
size());
} else {
new (end()) value_type(std::forward<Args>(args)...);
}
this->setSize(size() + 1);
return back();
}
void push_back(value_type&& t) {
emplace_back(std::move(t));
}
void push_back(value_type const& t) {
emplace_back(t);
}
void pop_back() {
erase(end() - 1);
}
iterator insert(const_iterator constp, value_type&& t) {
iterator p = unconst(constp);
if (p == end()) {
push_back(std::move(t));
return end() - 1;
}
auto offset = p - begin();
if (capacity() == size()) {
makeSize(
size() + 1,
[&t](void* ptr) { new (ptr) value_type(std::move(t)); },
offset);
this->setSize(this->size() + 1);
} else {
detail::moveObjectsRightAndCreate(
data() + offset,
data() + size(),
data() + size() + 1,
[&](size_t i) -> value_type&& {
assert(i == 0);
(void)i;
return std::move(t);
});
this->setSize(size() + 1);
}
return begin() + offset;
}
iterator insert(const_iterator p, value_type const& t) {
// Make a copy and forward to the rvalue value_type&& overload
// above.
return insert(p, value_type(t));
}
iterator insert(const_iterator pos, size_type n, value_type const& val) {
auto offset = pos - begin();
makeSize(size() + n);
detail::moveObjectsRightAndCreate(
data() + offset,
data() + size(),
data() + size() + n,
[&](size_t i) -> value_type const& {
assert(i < n);
(void)i;
return val;
});
this->setSize(size() + n);
return begin() + offset;
}
template <class Arg>
iterator insert(const_iterator p, Arg arg1, Arg arg2) {
// Forward using std::is_arithmetic to get to the proper
// implementation; this disambiguates between the iterators and
// (size_t, value_type) meaning for this function.
return insertImpl(unconst(p), arg1, arg2, std::is_arithmetic<Arg>());
}
iterator insert(const_iterator p, std::initializer_list<value_type> il) {
return insert(p, il.begin(), il.end());
}
iterator erase(const_iterator q) {
std::move(unconst(q) + 1, end(), unconst(q));
(data() + size() - 1)->~value_type();
this->setSize(size() - 1);
return unconst(q);
}
iterator erase(const_iterator q1, const_iterator q2) {
if (q1 == q2) {
return unconst(q1);
}
std::move(unconst(q2), end(), unconst(q1));
for (auto it = (end() - std::distance(q1, q2)); it != end(); ++it) {
it->~value_type();
}
this->setSize(size() - (q2 - q1));
return unconst(q1);
}
void clear() {
erase(begin(), end());
}
template <class Arg>
void assign(Arg first, Arg last) {
clear();
insert(end(), first, last);
}
void assign(std::initializer_list<value_type> il) {
assign(il.begin(), il.end());
}
void assign(size_type n, const value_type& t) {
clear();
insert(end(), n, t);
}
reference front() {
assert(!empty());
return *begin();
}
reference back() {
assert(!empty());
return *(end() - 1);
}
const_reference front() const {
assert(!empty());
return *begin();
}
const_reference back() const {
assert(!empty());
return *(end() - 1);
}
reference operator[](size_type i) {
assert(i < size());
return *(begin() + i);
}
const_reference operator[](size_type i) const {
assert(i < size());
return *(begin() + i);
}
reference at(size_type i) {
if (i >= size()) {
throw_exception<std::out_of_range>("index out of range");
}
return (*this)[i];
}
const_reference at(size_type i) const {
if (i >= size()) {
throw_exception<std::out_of_range>("index out of range");
}
return (*this)[i];
}
private:
static iterator unconst(const_iterator it) {
return const_cast<iterator>(it);
}
// The std::false_type argument is part of disambiguating the
// iterator insert functions from integral types (see insert().)
template <class It>
iterator insertImpl(iterator pos, It first, It last, std::false_type) {
using categ = typename std::iterator_traits<It>::iterator_category;
using it_ref = typename std::iterator_traits<It>::reference;
if (std::is_same<categ, std::input_iterator_tag>::value) {
auto offset = pos - begin();
while (first != last) {
pos = insert(pos, *first++);
++pos;
}
return begin() + offset;
}
auto const distance = std::distance(first, last);
auto const offset = pos - begin();
assert(distance >= 0);
assert(offset >= 0);
makeSize(size() + distance);
detail::moveObjectsRightAndCreate(
data() + offset,
data() + size(),
data() + size() + distance,
[&](size_t i) -> it_ref {
assert(i < size_t(distance));
return *(first + i);
});
this->setSize(size() + distance);
return begin() + offset;
}
iterator
insertImpl(iterator pos, size_type n, const value_type& val, std::true_type) {
// The true_type means this should call the size_t,value_type
// overload. (See insert().)
return insert(pos, n, val);
}
// The std::false_type argument came from std::is_arithmetic as part
// of disambiguating an overload (see the comment in the
// constructor).
template <class It>
void constructImpl(It first, It last, std::false_type) {
typedef typename std::iterator_traits<It>::iterator_category categ;
if (std::is_same<categ, std::input_iterator_tag>::value) {
// With iterators that only allow a single pass, we can't really
// do anything sane here.
while (first != last) {
emplace_back(*first++);
}
return;
}
auto distance = std::distance(first, last);
makeSize(distance);
this->setSize(distance);
{
auto rollback = makeGuard([&] {
if (this->isExtern()) {
u.freeHeap();
}
});
detail::populateMemForward(
data(), distance, [&](void* p) { new (p) value_type(*first++); });
rollback.dismiss();
}
}
template <typename InitFunc>
void doConstruct(size_type n, InitFunc&& func) {
makeSize(n);
this->setSize(n);
{
auto rollback = makeGuard([&] {
if (this->isExtern()) {
u.freeHeap();
}
});
detail::populateMemForward(data(), n, std::forward<InitFunc>(func));
rollback.dismiss();
}
}
// The true_type means we should forward to the size_t,value_type
// overload.
void constructImpl(size_type n, value_type const& val, std::true_type) {
doConstruct(n, [&](void* p) { new (p) value_type(val); });
}
/*
* Compute the size after growth.
*/
size_type computeNewSize() const {
return std::min((3 * capacity()) / 2 + 1, max_size());
}
void makeSize(size_type newSize) {
makeSizeInternal(newSize, false, [](void*) { assume_unreachable(); }, 0);
}
template <typename EmplaceFunc>
void makeSize(size_type newSize, EmplaceFunc&& emplaceFunc, size_type pos) {
assert(size() == capacity());
makeSizeInternal(
newSize, true, std::forward<EmplaceFunc>(emplaceFunc), pos);
}
/*
* Ensure we have a large enough memory region to be size `newSize'.
* Will move/copy elements if we are spilling to heap_ or needed to
* allocate a new region, but if resized in place doesn't initialize
* anything in the new region. In any case doesn't change size().
* Supports insertion of new element during reallocation by given
* pointer to new element and position of new element.
* NOTE: If reallocation is not needed, insert must be false,
* because we only know how to emplace elements into new memory.
*/
template <typename EmplaceFunc>
void makeSizeInternal(
size_type newSize,
bool insert,
EmplaceFunc&& emplaceFunc,
size_type pos) {
if (newSize > max_size()) {
throw_exception<std::length_error>("max_size exceeded in small_vector");
}
if (newSize <= capacity()) {
assert(!insert);
return;
}
assert(this->kShouldUseHeap);
// This branch isn't needed for correctness, but allows the optimizer to
// skip generating code for the rest of this function in NoHeap
// small_vectors.
if (!this->kShouldUseHeap) {
return;
}
newSize = std::max(newSize, computeNewSize());
auto needBytes = newSize * sizeof(value_type);
// If the capacity isn't explicitly stored inline, but the heap
// allocation is grown to over some threshold, we should store
// a capacity at the front of the heap allocation.
bool heapifyCapacity =
!kHasInlineCapacity && needBytes > kHeapifyCapacityThreshold;
if (heapifyCapacity) {
needBytes += kHeapifyCapacitySize;
}
auto const sizeBytes = goodMallocSize(needBytes);
void* newh = checkedMalloc(sizeBytes);
// We expect newh to be at least 2-aligned, because we want to
// use its least significant bit as a flag.
assert(!detail::pointerFlagGet(newh));
value_type* newp = static_cast<value_type*>(
heapifyCapacity ? detail::shiftPointer(newh, kHeapifyCapacitySize)
: newh);
{
auto rollback = makeGuard([&] { //
free(newh);
});
if (insert) {
// move and insert the new element
this->moveToUninitializedEmplace(
begin(), end(), newp, pos, std::forward<EmplaceFunc>(emplaceFunc));
} else {
// move without inserting new element
this->moveToUninitialized(begin(), end(), newp);
}
rollback.dismiss();
}
for (auto& val : *this) {
val.~value_type();
}
if (this->isExtern()) {
u.freeHeap();
}
auto availableSizeBytes = sizeBytes;
if (heapifyCapacity) {
u.pdata_.heap_ = detail::pointerFlagSet(newh);
availableSizeBytes -= kHeapifyCapacitySize;
} else {
u.pdata_.heap_ = newh;
}
this->setExtern(true);
this->setCapacity(availableSizeBytes / sizeof(value_type));
}
/*
* This will set the capacity field, stored inline in the storage_ field
* if there is sufficient room to store it.
*/
void setCapacity(size_type newCapacity) {
assert(this->isExtern());
if (u.hasCapacity()) {
assert(newCapacity < std::numeric_limits<InternalSizeType>::max());
u.setCapacity(newCapacity);
}
}
private:
struct HeapPtrWithCapacity {
void* heap_;
InternalSizeType capacity_;
InternalSizeType getCapacity() const {
return capacity_;
}
void setCapacity(InternalSizeType c) {
capacity_ = c;
}
} FOLLY_SV_PACK_ATTR;
struct HeapPtr {
// Lower order bit of heap_ is used as flag to indicate whether capacity is
// stored at the front of the heap allocation.
void* heap_;
InternalSizeType getCapacity() const {
assert(detail::pointerFlagGet(heap_));
return *static_cast<InternalSizeType*>(detail::pointerFlagClear(heap_));
}
void setCapacity(InternalSizeType c) {
*static_cast<InternalSizeType*>(detail::pointerFlagClear(heap_)) = c;
}
} FOLLY_SV_PACK_ATTR;
typedef aligned_storage_for_t<value_type[MaxInline]> InlineStorageDataType;
typedef typename std::conditional<
sizeof(value_type) * MaxInline != 0,
InlineStorageDataType,
void*>::type InlineStorageType;
static bool constexpr kHasInlineCapacity =
sizeof(HeapPtrWithCapacity) < sizeof(InlineStorageType);
// This value should we multiple of word size.
static size_t constexpr kHeapifyCapacitySize = sizeof(
typename std::
aligned_storage<sizeof(InternalSizeType), alignof(value_type)>::type);
// Threshold to control capacity heapifying.
static size_t constexpr kHeapifyCapacityThreshold =
100 * kHeapifyCapacitySize;
typedef typename std::
conditional<kHasInlineCapacity, HeapPtrWithCapacity, HeapPtr>::type
PointerType;
union Data {
explicit Data() {
pdata_.heap_ = nullptr;
}
PointerType pdata_;
InlineStorageType storage_;
value_type* buffer() noexcept {
void* vp = &storage_;
return static_cast<value_type*>(vp);
}
value_type const* buffer() const noexcept {
return const_cast<Data*>(this)->buffer();
}
value_type* heap() noexcept {
if (kHasInlineCapacity || !detail::pointerFlagGet(pdata_.heap_)) {
return static_cast<value_type*>(pdata_.heap_);
} else {
return static_cast<value_type*>(detail::shiftPointer(
detail::pointerFlagClear(pdata_.heap_), kHeapifyCapacitySize));
}
}
value_type const* heap() const noexcept {
return const_cast<Data*>(this)->heap();
}
bool hasCapacity() const {
return kHasInlineCapacity || detail::pointerFlagGet(pdata_.heap_);
}
InternalSizeType getCapacity() const {
return pdata_.getCapacity();
}
void setCapacity(InternalSizeType c) {
pdata_.setCapacity(c);
}
void freeHeap() {
auto vp = detail::pointerFlagClear(pdata_.heap_);
free(vp);
}
} u;
};
FOLLY_SV_PACK_POP
//////////////////////////////////////////////////////////////////////
// Basic guarantee only, or provides the nothrow guarantee iff T has a
// nothrow move or copy constructor.
template <class T, std::size_t MaxInline, class A, class B, class C>
void swap(
small_vector<T, MaxInline, A, B, C>& a,
small_vector<T, MaxInline, A, B, C>& b) {
a.swap(b);
}
template <class T, std::size_t MaxInline, class A, class B, class C, class U>
void erase(small_vector<T, MaxInline, A, B, C>& v, U value) {
v.erase(std::remove(v.begin(), v.end(), value), v.end());
}
template <
class T,
std::size_t MaxInline,
class A,
class B,
class C,
class Predicate>
void erase_if(small_vector<T, MaxInline, A, B, C>& v, Predicate predicate) {
v.erase(std::remove_if(v.begin(), v.end(), predicate), v.end());
}
//////////////////////////////////////////////////////////////////////
namespace detail {
// Format support.
template <class T, size_t M, class A, class B, class C>
struct IndexableTraits<small_vector<T, M, A, B, C>>
: public IndexableTraitsSeq<small_vector<T, M, A, B, C>> {};
} // namespace detail
} // namespace folly
FOLLY_POP_WARNING
#undef FOLLY_SV_PACK_ATTR
#undef FOLLY_SV_PACK_PUSH
#undef FOLLY_SV_PACK_POP
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