C++ 概念： Allocator

 

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C++ 的概念

基礎
DefaultConstructible CopyAssignable CopyConstructible	MoveAssignable （C++11） MoveConstructible （C++11） Destructible
庫
EqualityComparable LessThanComparable Swappable （C++11） ValueSwappable （C++11）	NullablePointer （C++11） Hash （C++11） Allocator
容器
Container SequenceContainer ReversibleContainer	AssociativeContainer AllocatorAwareContainer UnorderedAssociativeContainer （C++11）
容器元素
CopyInsertable （C++11） MoveInsertable （C++11）	EmplaceConstructible （C++11）
迭代器
Iterator OutputIterator InputIterator	ForwardIterator BidirectionalIterator RandomAccessIterator
隨機數
SeedSequence （C++11） RandomNumberEngine （C++11）	RandomNumberDistribution （C++11） UniformRandomNumberGenerator （C++11） RandomNumberEngineAdaptor （C++11）
並發
BasicLockable （C++11） Lockable （C++11） TimedLockable （C++11）	Mutex （C++11） TimedMutex （C++11）
其它
CharTraits pos_type off_type Clock （C++11）	UnaryTypeTrait （C++11） BinaryTypeTrait （C++11） TransformationTrait （C++11） TrivialClock （C++11）

 

封裝內存分配和釋放策略.

Original:

Encapsulates memory allocation and deallocation strategy.

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每一個標準庫組件，可能需要分配或釋放存儲，從std::string，std::vector，和每一個容器除了std::array，以std::shared_ptrstd::function，通過Allocator：滿足以下要求的類類型的對象.....

Original:

Every standard library component that may need to allocate or release storage, from std::string, std::vector, and every container except std::array, to std::shared_ptr and std::function, does so through an Allocator: an object of a class type that satisfies the following requirements.

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有些要求是可選的：模板std::allocator_traits提供的默認實現所有可選的要求，和所有的標準庫容器和其他分配器感知類訪問的分配器通過std::allocator_traits，而不是直接.

Original:

Some requirements are optional: the template std::allocator_traits supplies the default implementations for all optional requirements, and all standard library containers and other allocator-aware classes access the allocator through std::allocator_traits, not directly.

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要求

鑒於

Original:

Given

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• A，的分配器類型T

  Original:

  A, an Allocator for type T

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• B，相同類型U分配器

  Original:

  B, the same Allocator for type U

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• ptr，allocator_traits<A>::pointer類型的值，通過調用allocator_traits<A>::allocate()

  Original:

  ptr, a value of type allocator_traits<A>::pointer, obtained by calling allocator_traits<A>::allocate()

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• cptr，allocator_traits<A>::const_pointer類型的值，得到的轉換，從ptr

  Original:

  cptr, a value of type allocator_traits<A>::const_pointer, obtained by conversion from ptr

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• vptr，allocator_traits<A>::void_pointer類型的值，得到的轉換，從ptr

  Original:

  vptr, a value of type allocator_traits<A>::void_pointer, obtained by conversion from ptr

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• cvptr，值類型allocator_traits<A>::const_void_pointer，得到的轉換cptr或vptr

  Original:

  cvptr, a value of type allocator_traits<A>::const_void_pointer, obtained by conversion from cptr or from vptr

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• xptr的dereferencable的指針某種類型X

  Original:

  xptr, a dereferencable pointer to some type X

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Expression	Requirements	Return type
A::pointer （可選的）	Satisfies NullablePointer and RandomAccessIterator
A::const_pointer （可選的）	A::pointer is convertible to A::const_pointer. Satisfies NullablePointer and RandomAccessIterator
A::void_pointer （可選的）	A::pointer is convertible to A::void_pointer B::void_pointer和A::void_pointer是相同的類型。滿足NullablePointer Original: B::void_pointer and A::void_pointer are the same type. Satisfies NullablePointer The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
A::const_void_pointer （可選的）	A::pointer, A::const_pointer, and A::void_pointer are convertible to A::const_void_pointer B::const_void_pointer和A::const_void_pointer是相同的類型。滿足NullablePointer Original: B::const_void_pointer and A::const_void_pointer are the same type. Satisfies NullablePointer The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
A::value_type		the type T
A::size_type （可選的）	A::size_type can represent the size of the largest object A can allocate	unsigned integer type
A::difference_type （可選的）	A::difference_type can represent the difference of any two pointers to the objects allocated by A	signed integer type
A::template rebind<U>::other （可選的[1]）	for any U, B::template rebind<T>::other is A	the type B
*ptr		T&
*cptr	*cptr and *ptr identify the same object	const T&
ptr->m	same as (*ptr).m, if (*ptr).m is well-defined	the type of T::m
cptr->m	same as (*cptr).m, if (*cptr).m is well-defined	the type of T::m
static_cast<A::pointer>(vptr)	static_cast<A::pointer>(vptr) == ptr	A::pointer
static_cast<A::const_pointer>(cvptr)	static_cast<A::const_pointer>(vptr) == cptr	A::const_pointer
a.allocate(n)	allocates storage suitable for n objects of type T, but does not construct them. May throw exceptions.	A::pointer
a.allocate(n, cptr) （可選的）	same as a.allocate(n), but may use cptr in unspecified manner to aid locality	A::pointer
a.deallocate(ptr, n)	deallocates storage previously allocated by a call to a.allocate(n). Does not call destructors, if any objects were constructed, they must be destroyed before calling a.deallocate(). Does not throw exceptions.	(not used)
a.max_size() （可選的）	the largest value that can be passed to A::allocate()	A::size_type
a1 == a2	returns true only if the storage allocated by the allocator a1 can be deallocated through a2. Establishes reflexive, symmetric, and transitive relationship. Does not throw exceptions.	bool
a1 != a2	same as !(a1==a2)	bool
A a1(a)	Copy-constructs a1 such that a1 == a. Does not throw exceptions.
A a(b)	Constructs a such that B(a)==b and A(b)==a. Does not throw exceptions.
A a1(std::move(a))	Constructs a1 such that it equals the prior value of a. Does not throw exceptions.
A a(std::move(b))	Constructs a such that it equals the prior value of A(b). Does not throw exceptions.
a.construct(xptr, args) （可選的）	Constructs an object of type X in previously-allocated storage at the address pointed to by xptr, using args as the constructor arguments
a.destroy(xptr) （可選的）	Destructs an object of type X pointed to by xptr, but does not deallocate any storage.
a.select_on_container_copy_construction() （可選的）	Provides an instance of A to be used by the container that is copy-constructed from the one that uses a currently. Usually returns either a copy of a or a default-constructed A().	A
a.propagate_on_container_copy_assignment （可選的）	true if the allocator of type A needs to be copied when the container that uses it is copy-assigned	std::true_type or std::false_type or derived from such
a.propagate_on_container_move_assignment （可選的）	true if the allocator of type A needs to be copied when the container that uses it is move-assigned	std::true_type or std::false_type or derived from such
a.propagate_on_container_swap （可選的）	true if the allocators of type A need to be swapped when two containers that use them are swapped	std::true_type or std::false_type or derived from such

注意事項：

Original:

Notes:

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[1]重新綁定是唯一可選的（提供由std :: allocator_traits），如果這分配器模板的形式SomeAllocator的，<T, Args>，args是零個或多個額外的模板參數.

Original:

[1] rebind is only optional (provided by std::allocator_traits) if this allocator is a template of the form SomeAllocator<T, Args>, where Args is zero or more additional template parameters.

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