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boost_container/include/boost/container/small_vector.hpp
Ion Gaztañaga 8cdfec7890 Add experimental small_vector class
2015-02-26 00:35:59 +01:00

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//////////////////////////////////////////////////////////////////////////////
//
// (C) Copyright Ion Gaztanaga 2015-2015. Distributed under the Boost
// Software License, Version 1.0. (See accompanying file
// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
// See http://www.boost.org/libs/container for documentation.
//
//////////////////////////////////////////////////////////////////////////////
#ifndef BOOST_CONTAINER_CONTAINER_SMALL_VECTOR_HPP
#define BOOST_CONTAINER_CONTAINER_SMALL_VECTOR_HPP
#ifndef BOOST_CONFIG_HPP
# include <boost/config.hpp>
#endif
#if defined(BOOST_HAS_PRAGMA_ONCE)
# pragma once
#endif
#include <boost/container/detail/config_begin.hpp>
#include <boost/container/detail/workaround.hpp>
// container
#include <boost/container/container_fwd.hpp>
#include <boost/container/vector.hpp>
#include <boost/container/allocator_traits.hpp>
#include <boost/container/new_allocator.hpp> //new_allocator
// container/detail
#include <boost/container/detail/type_traits.hpp>
#include <boost/container/detail/version_type.hpp>
//move
#include <boost/move/adl_move_swap.hpp>
#include <boost/move/iterator.hpp>
//move/detail
#if defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES)
#include <boost/move/detail/fwd_macros.hpp>
#endif
//std
#if !defined(BOOST_NO_CXX11_HDR_INITIALIZER_LIST)
#include <initializer_list> //for std::initializer_list
#endif
namespace boost {
namespace container {
template <class T, class Allocator = new_allocator<T> >
class small_vector_base;
/////////////////////////////////////////////////////
//
// small_vector_allocator
//
/////////////////////////////////////////////////////
template<class Allocator>
class small_vector_allocator
: public Allocator
{
typedef unsigned int allocation_type;
#ifndef BOOST_CONTAINER_DOXYGEN_INVOKED
private:
//Self type
typedef small_vector_allocator<Allocator> self_t;
BOOST_COPYABLE_AND_MOVABLE(small_vector_allocator)
#endif //#ifndef BOOST_CONTAINER_DOXYGEN_INVOKED
const Allocator &as_base() const
{ return static_cast<const Allocator&>(*this); }
Allocator &as_base()
{ return static_cast<Allocator&>(*this); }
public:
#ifndef BOOST_CONTAINER_DOXYGEN_INVOKED
typedef allocator_traits<Allocator> allocator_traits_type;
typedef typename
container_detail::version<Allocator>::type version;
#endif //#ifndef BOOST_CONTAINER_DOXYGEN_INVOKED
typedef typename allocator_traits<Allocator>::value_type value_type;
typedef typename allocator_traits<Allocator>::pointer pointer;
typedef typename allocator_traits<Allocator>::const_pointer const_pointer;
typedef typename allocator_traits<Allocator>::reference reference;
typedef typename allocator_traits<Allocator>::const_reference const_reference;
typedef typename allocator_traits<Allocator>::size_type size_type;
typedef typename allocator_traits<Allocator>::difference_type difference_type;
typedef typename allocator_traits<Allocator>::void_pointer void_pointer;
typedef typename allocator_traits<Allocator>::const_void_pointer const_void_pointer;
typedef typename allocator_traits_type::propagate_on_container_copy_assignment propagate_on_container_copy_assignment;
typedef typename allocator_traits_type::propagate_on_container_move_assignment propagate_on_container_move_assignment;
typedef typename allocator_traits_type::propagate_on_container_swap propagate_on_container_swap;
typedef container_detail::bool_<false> is_always_equal;
typedef container_detail::bool_<true> is_partially_propagable;
//!Obtains an small_vector_allocator that allocates
//!objects of type T2
template<class T2>
struct rebind
{
typedef typename allocator_traits_type::template rebind_alloc<T2>::type other;
};
#if !defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES) || defined(BOOST_CONTAINER_DOXYGEN_INVOKED)
//!Constructor from arbitrary arguments
template<class ...Args>
explicit small_vector_allocator(BOOST_FWD_REF(Args) ...args)
: Allocator(::boost::forward<Args>(args)...)
{}
#else
#define BOOST_CONTAINER_SMALL_VECTOR_ALLOCATOR_CTOR_CODE(N) \
BOOST_MOVE_TMPL_LT##N BOOST_MOVE_CLASS##N BOOST_MOVE_GT##N \
explicit small_vector_allocator(BOOST_MOVE_UREF##N)\
: Allocator(BOOST_MOVE_FWD##N)\
{}\
//
BOOST_MOVE_ITERATE_0TO9(BOOST_CONTAINER_SMALL_VECTOR_ALLOCATOR_CTOR_CODE)
#undef BOOST_CONTAINER_SMALL_VECTOR_ALLOCATOR_CTOR_CODE
#endif
//!Constructor from other small_vector_allocator.
//!Never throws
small_vector_allocator(const small_vector_allocator &other) BOOST_NOEXCEPT_OR_NOTHROW
: Allocator(other.as_base())
{}
//!Move constructor from small_vector_allocator.
//!Never throws
small_vector_allocator(BOOST_RV_REF(small_vector_allocator) other) BOOST_NOEXCEPT_OR_NOTHROW
: Allocator(::boost::move(other.as_base()))
{}
//!Constructor from related small_vector_allocator.
//!Never throws
template<class OtherAllocator>
small_vector_allocator(const small_vector_allocator<OtherAllocator> &other) BOOST_NOEXCEPT_OR_NOTHROW
: Allocator(other.as_base())
{}
//!Move constructor from related small_vector_allocator.
//!Never throws
template<class OtherAllocator>
small_vector_allocator(BOOST_RV_REF(small_vector_allocator<OtherAllocator>) other) BOOST_NOEXCEPT_OR_NOTHROW
: Allocator(::boost::move(other.as_base()))
{}
//!Assignment from other small_vector_allocator.
//!Never throws
small_vector_allocator & operator=(BOOST_COPY_ASSIGN_REF(small_vector_allocator) other) BOOST_NOEXCEPT_OR_NOTHROW
{ return static_cast<small_vector_allocator&>(this->Allocator::operator=(other.as_base())); }
//!Move constructor from other small_vector_allocator.
//!Never throws
small_vector_allocator & operator=(BOOST_RV_REF(small_vector_allocator) other) BOOST_NOEXCEPT_OR_NOTHROW
{ return static_cast<small_vector_allocator&>(this->Allocator::operator=(::boost::move(other.as_base()))); }
//!Assignment from related small_vector_allocator.
//!Never throws
template<class OtherAllocator>
small_vector_allocator & operator=(BOOST_COPY_ASSIGN_REF(small_vector_allocator<OtherAllocator>) other) BOOST_NOEXCEPT_OR_NOTHROW
{ return static_cast<small_vector_allocator&>(this->Allocator::operator=(other.as_base())); }
//!Move assignment from related small_vector_allocator.
//!Never throws
template<class OtherAllocator>
small_vector_allocator & operator=(BOOST_RV_REF(small_vector_allocator<OtherAllocator>) other) BOOST_NOEXCEPT_OR_NOTHROW
{ return static_cast<small_vector_allocator&>(this->Allocator::operator=(::boost::move(other.as_base()))); }
pointer allocate(size_type count, const_void_pointer hint)
{ return allocator_traits_type::allocate(this->as_base(), count, hint); }
//!Deallocates previously allocated memory.
//!Never throws
void deallocate(pointer ptr, size_type n) BOOST_NOEXCEPT_OR_NOTHROW
{
if(!this->is_internal_storage(ptr))
allocator_traits_type::deallocate(this->as_base(), ptr, n);
}
//!Returns the maximum number of elements that could be allocated.
//!Never throws
size_type max_size() const BOOST_NOEXCEPT_OR_NOTHROW
{ return allocator_traits_type::max_size(this->as_base()); }
small_vector_allocator select_on_container_copy_construction() const
{ return small_vector_allocator(allocator_traits_type::select_on_container_copy_construction(this->as_base())); }
bool storage_can_be_propagated(pointer p, const small_vector_allocator &to, const bool propagate_a) const
{
return !this->is_internal_storage(p) &&
allocator_traits_type::storage_can_be_propagated(this->as_base(), p, to.as_base(), propagate_a);
}
//!Swaps two allocators, does nothing
//!because this small_vector_allocator is stateless
friend void swap(self_t &l, self_t &r) BOOST_NOEXCEPT_OR_NOTHROW
{ boost::adl_move_swap(l.as_base(), r.as_base()); }
//!An small_vector_allocator always compares to true, as memory allocated with one
//!instance can be deallocated by another instance
friend bool operator==(const small_vector_allocator &, const small_vector_allocator &) BOOST_NOEXCEPT_OR_NOTHROW
{ return false; }
//!An small_vector_allocator always compares to false, as memory allocated with one
//!instance can be deallocated by another instance
friend bool operator!=(const small_vector_allocator &, const small_vector_allocator &) BOOST_NOEXCEPT_OR_NOTHROW
{ return true; }
/*
//!An advanced function that offers in-place expansion shrink to fit and new allocation
//!capabilities. Memory allocated with this function can only be deallocated with deallocate()
//!or deallocate_many().
//!This function is available only with Version == 2
pointer allocation_command(allocation_type command,
size_type limit_size,
size_type &prefer_in_recvd_out_size,
pointer &reuse)
{ return allocator_traits_type::allocation_command(command, limit_size, prefer_in_recvd_out_size, reuse); }
//!Returns maximum the number of objects the previously allocated memory
//!pointed by p can hold.
//!Memory must not have been allocated with
//!allocate_one or allocate_individual.
//!This function is available only with Version == 2
size_type size(pointer p) const BOOST_NOEXCEPT_OR_NOTHROW
{ return allocator_traits_type::size(p); }
*/
private:
//!Allocates just one object. Memory allocated with this function
//!must be deallocated only with deallocate_one().
//!Throws bad_alloc if there is no enough memory
//!This function is available only with Version == 2
/*
using Allocator::allocate_one;
using Allocator::allocate_individual;
using Allocator::deallocate_one;
using Allocator::deallocate_individual;
using Allocator::allocate_many;
using Allocator::deallocate_many;*/
private:
bool is_internal_storage(pointer p) const
{ return this->internal_storage() == p; }
pointer internal_storage() const
{
typedef typename Allocator::value_type value_type;
typedef container_detail::vector_alloc_holder< small_vector_allocator<Allocator> > vector_alloc_holder_t;
typedef vector<value_type, small_vector_allocator<Allocator> > vector_base;
typedef small_vector_base<value_type, Allocator> derived_type;
//
const vector_alloc_holder_t &v_holder = static_cast<const vector_alloc_holder_t &>(*this);
const vector_base &v_base = reinterpret_cast<const vector_base &>(v_holder);
const derived_type &d_base = static_cast<const derived_type &>(v_base);
return d_base.internal_storage();
}
};
/////////////////////////////////////////////////////
//
// small_vector_base
//
/////////////////////////////////////////////////////
template <class T, class SecondaryAllocator>
class small_vector_base
: public vector<T, small_vector_allocator<SecondaryAllocator> >
{
typedef typename allocator_traits<SecondaryAllocator>::pointer pointer;
BOOST_COPYABLE_AND_MOVABLE(small_vector_base)
public:
typedef vector<T, small_vector_allocator<SecondaryAllocator> > base_type;
typedef typename container_detail::aligned_storage
<sizeof(T), container_detail::alignment_of<T>::value>::type storage_type;
typedef small_vector_allocator<SecondaryAllocator> allocator_type;
pointer internal_storage() const BOOST_NOEXCEPT_OR_NOTHROW
{ return boost::intrusive::pointer_traits<pointer>::pointer_to(*const_cast<T*>(static_cast<const T*>(static_cast<const void*>(&m_storage_start)))); }
protected:
base_type &as_base() { return static_cast<base_type&>(*this); }
const base_type &as_base() const { return static_cast<const base_type&>(*this); }
typedef typename base_type::initial_capacity_t initial_capacity_t;
explicit small_vector_base(initial_capacity_t, std::size_t initial_capacity)
: base_type(initial_capacity_t(), this->internal_storage(), initial_capacity)
{}
template<class AllocFwd>
explicit small_vector_base(initial_capacity_t, std::size_t capacity, BOOST_FWD_REF(AllocFwd) a)
: base_type(initial_capacity_t(), this->internal_storage(), capacity, ::boost::forward<AllocFwd>(a))
{}
~small_vector_base(){}
small_vector_base& operator=(BOOST_COPY_ASSIGN_REF(small_vector_base) other)
{ return static_cast<small_vector_base&>(this->base_type::operator=(static_cast<base_type const&>(other))); }
small_vector_base& operator=(BOOST_RV_REF(small_vector_base) other)
{ return static_cast<small_vector_base&>(this->base_type::operator=(BOOST_MOVE_BASE(base_type, other))); }
void swap(small_vector_base &other)
{ return this->base_type::swap(other); }
using base_type::is_propagable_from;
using base_type::steal_resources;
private:
//The only member
storage_type m_storage_start;
};
/////////////////////////////////////////////////////
//
// small_vector_storage_calculator
//
/////////////////////////////////////////////////////
template<std::size_t Needed, std::size_t Hdr, std::size_t SSize, bool NeedsZero = (0u == Needed || Needed <= Hdr)>
struct small_vector_storage_calculator_helper
{
static const std::size_t value = (Needed - Hdr - 1u)/SSize + 1u;
};
template<std::size_t Needed, std::size_t Hdr, std::size_t SSize>
struct small_vector_storage_calculator_helper<Needed, Hdr, SSize, true>
{
static const std::size_t value = 0u;
};
template<class Storage, class Allocator, class T, std::size_t N>
struct small_vector_storage_calculator
{
typedef small_vector_base<T, Allocator> svh_type;
typedef typename svh_type::base_type svhb_type;
static const std::size_t s_align = container_detail::alignment_of<Storage>::value;
static const std::size_t s_size = sizeof(Storage);
static const std::size_t svh_sizeof = sizeof(svh_type);
static const std::size_t svhb_sizeof = sizeof(svhb_type);
static const std::size_t s_start = ((svhb_sizeof-1)/s_align+1)*s_align;
static const std::size_t header_bytes = svh_sizeof-s_start;
static const std::size_t needed_bytes = sizeof(T)*N;
static const std::size_t needed_extra_storages =
small_vector_storage_calculator_helper<needed_bytes, header_bytes, s_size>::value;
};
/////////////////////////////////////////////////////
//
// small_vector_storage_definer
//
/////////////////////////////////////////////////////
template<class Storage, std::size_t N>
struct small_vector_storage
{
Storage m_rest_of_storage[N];
};
template<class Storage>
struct small_vector_storage<Storage, 0>
{};
template<class Allocator, std::size_t N>
struct small_vector_storage_definer
{
typedef typename Allocator::value_type value_type;
typedef typename small_vector_base<value_type, Allocator>::storage_type storage_type;
static const std::size_t needed_extra_storages =
small_vector_storage_calculator<storage_type, Allocator, value_type, N>::needed_extra_storages;
typedef small_vector_storage<storage_type, needed_extra_storages> type;
};
//! small_vector a vector-like container optimized for the case when it contains few elements.
//! It contains some preallocated elements in-place, which allows it to avoid the use of the small_vector_allocator
//! when the actual number of elements is below that preallocated threshold.
//!
//! small_vector<T, N, Allocator> is convertible to small_vector_unbounded<T, Allocator> that is independent
//! from the preallocated element capacity, so client code does not need to be templated on that N argument.
//!
//! \tparam T The type of object that is stored in the small_vector
//! \tparam N The number of preallocated elements stored inside small_vector. It shall be less than Allocator::max_size();
//! \tparam Allocator The small_vector_allocator used for memory management when the number of elements exceeds N.
template <class T, std::size_t N, class Allocator BOOST_CONTAINER_DOCONLY(= new_allocator<T>) >
class small_vector : public small_vector_base<T, Allocator>
, private small_vector_storage_definer<Allocator, N>::type
{
typedef small_vector_base<T, Allocator> base_type;
typedef typename small_vector_storage_definer<Allocator, N>::type remaining_storage_holder;
BOOST_COPYABLE_AND_MOVABLE(small_vector)
typedef typename base_type::initial_capacity_t initial_capacity_t;
typedef allocator_traits<typename base_type::allocator_type> allocator_traits_type;
public:
typedef small_vector_storage_calculator< typename small_vector_base<T, Allocator>
::storage_type, Allocator, T, N> storage_test;
static const std::size_t needed_extra_storages = storage_test::needed_extra_storages;
static const std::size_t needed_bytes = storage_test::needed_bytes;
static const std::size_t header_bytes = storage_test::header_bytes;
static const std::size_t s_start = storage_test::s_start;
typedef typename base_type::allocator_type allocator_type;
typedef typename base_type::size_type size_type;
static std::size_t internal_capacity()
{ return (sizeof(small_vector) - storage_test::s_start)/sizeof(T); }
small_vector()
: base_type(initial_capacity_t(), internal_capacity())
{}
explicit small_vector(size_type n)
: base_type(initial_capacity_t(), internal_capacity())
{ this->resize(n); }
explicit small_vector(const allocator_type &a)
: base_type(initial_capacity_t(), internal_capacity(), a)
{}
small_vector(size_type n, const allocator_type &a)
: base_type(initial_capacity_t(), internal_capacity(), a)
{ this->resize(n); }
small_vector(const small_vector &other)
: base_type( initial_capacity_t(), internal_capacity()
, allocator_traits_type::select_on_container_copy_construction(other.get_stored_allocator()))
{ this->assign(other.cbegin(), other.cend()); }
small_vector(const small_vector &other, const allocator_type &a)
: base_type(initial_capacity_t(), internal_capacity(), a)
{ this->assign(other.cbegin(), other.cend()); }
small_vector(BOOST_RV_REF(small_vector) other)
: base_type(initial_capacity_t(), internal_capacity(), ::boost::move(other.get_stored_allocator()))
{ this->move_construct_impl(other, other.get_stored_allocator()); }
small_vector(BOOST_RV_REF(small_vector) other, const allocator_type &a)
: base_type(initial_capacity_t(), internal_capacity(), a)
{ this->move_construct_impl(other, a); }
small_vector& operator=(BOOST_COPY_ASSIGN_REF(small_vector) other)
{ return static_cast<small_vector&>(this->base_type::operator=(static_cast<base_type const&>(other))); }
small_vector& operator=(BOOST_RV_REF(small_vector) other)
{ return static_cast<small_vector&>(this->base_type::operator=(BOOST_MOVE_BASE(base_type, other))); }
void swap(small_vector &other)
{ return this->base_type::swap(other); }
private:
void move_construct_impl(small_vector &x, const allocator_type &a)
{
if(base_type::is_propagable_from(x, a, true)){
this->steal_resources(x);
}
else{
this->assign( boost::make_move_iterator(container_detail::iterator_to_raw_pointer(x.begin()))
, boost::make_move_iterator(container_detail::iterator_to_raw_pointer(x.end ()))
);
}
}
};
}}
#ifndef BOOST_CONTAINER_DOXYGEN_INVOKED
/*
namespace boost {
//!has_trivial_destructor_after_move<> == true_type
//!specialization for optimizations
template <class T, class Allocator>
struct has_trivial_destructor_after_move<boost::container::vector<T, Allocator> >
{
typedef typename ::boost::container::allocator_traits<Allocator>::pointer pointer;
static const bool value = ::boost::has_trivial_destructor_after_move<Allocator>::value &&
::boost::has_trivial_destructor_after_move<pointer>::value;
};
}
*/
#endif //#ifndef BOOST_CONTAINER_DOXYGEN_INVOKED
#include <boost/container/detail/config_end.hpp>
#endif // #ifndef BOOST_CONTAINER_CONTAINER_SMALL_VECTOR_HPP
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