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<div class="t-tr-text">C + +: concetti<div class="t-tr-dropdown"><div><div><div class="t-tr-dropdown-arrow-border"></div><div class="t-tr-dropdown-arrow"></div><div class="t-tr-dropdown-h">Original:</div><div class="t-tr-dropdown-orig">C++ concepts:</div><div class="t-tr-dropdown-notes">The text has been machine-translated via [http://translate.google.com Google Translate].<br/> You can help to correct and verify the translation. Click [http://en.cppreference.com/w/Cppreference:MachineTranslations here] for instructions.</div></div></div></div></div> Allocator

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<metanoindex/>

Incapsula allocazione di memoria e strategia deallocazione.

Original:

Encapsulates memory allocation and deallocation strategy.

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Ogni componente di libreria standard che potrebbe essere necessario allocare o liberare memoria, da std::string, std::vector, e ogni contenitore, tranne std::array, a std::shared_ptr e std::function, lo fa attraverso un Allocator: un oggetto di un tipo di classe che soddisfi i seguenti requisiti.

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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Alcuni requisiti sono opzionali: il std::allocator_traits modello fornisce le implementazioni di default per tutti i requisiti opzionali, e tutti i contenitori della libreria standard e altri allocatore-aware classi di accesso tramite l'allocatore std::allocator_traits, non direttamente.

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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Requisiti

Dato

Original:

Given

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A, un allocatore per T tipo
Original:
A, an Allocator for type T
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B, l'allocatore stesso per U tipo
Original:
B, the same Allocator for type U
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ptr, un valore di tipo allocator_traits<A>::pointer, ottenuto chiamando 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, un valore di tipo allocator_traits<A>::const_pointer, ottenuto dalla conversione da ptr
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cptr, a value of type allocator_traits<A>::const_pointer, obtained by conversion from ptr
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vptr, un valore di tipo allocator_traits<A>::void_pointer, ottenuto dalla conversione da ptr
Original:
vptr, a value of type allocator_traits<A>::void_pointer, obtained by conversion from ptr
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cvptr, un valore di tipo allocator_traits<A>::const_void_pointer, ottenuto dalla conversione da cptr o da vptr
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cvptr, a value of type allocator_traits<A>::const_void_pointer, obtained by conversion from cptr or from vptr
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xptr, un puntatore a qualche dereferencable X tipo
Original:
xptr, a dereferencable pointer to some type X
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Expression	Requirements	Return type
`A::pointer` (opzionale)	Satisfies `NullablePointer` and `RandomAccessIterator`
`A::const_pointer` (opzionale)	`A::pointer` is convertible to `A::const_pointer`. Satisfies `NullablePointer` and `RandomAccessIterator`
`A::void_pointer` (opzionale)	`A::pointer` is convertible to `A::void_pointer` `B::void_pointer` `A::void_pointer` e sono dello stesso tipo. Soddisfa `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` (opzionale)	`A::pointer`, `A::const_pointer`, and `A::void_pointer` are convertible to `A::const_void_pointer` `B::const_void_pointer` `A::const_void_pointer` e sono dello stesso tipo. Soddisfa `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` (opzionale)	`A::size_type` can represent the size of the largest object `A` can allocate	unsigned integer type
`A::difference_type` (opzionale)	`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` (opzionale [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)` (opzionale)	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()` (opzionale)	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)` (opzionale)	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)` (opzionale)	Destructs an object of type `X` pointed to by `xptr`, but does not deallocate any storage.
`a.select_on_container_copy_construction()` (opzionale)	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` (opzionale)	`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` (opzionale)	`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` (opzionale)	`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

Note:

Original:

Notes:

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[1] rebind è opzionale (fornito da std :: allocator_traits) se questo allocatore è un modello della forma SomeAllocator <T, Args>, dove Args è zero o più parametri di template aggiuntivi.

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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