This class defines a concrete mechanism that adapts the system-supplied (native) global operator new and operator delete to the Allocator protocol. The class method singleton returns a process-wide unique object of this class whose lifetime is guaranteed to extend from the first call to singleton until the program terminates. A second class method, allocator, allows for conveniently replacing a "null" allocator with this singleton object. Note that this entire class should generally not be used directly by typical clients (see bslma_default for more information).
| Name | Description |
|---|---|
Allocator | This protocol class provides a pure abstract interface and contract for clients and suppliers of raw memory. If the requested memory cannot be returned, the contract requires that an std::bad_alloc exception be thrown. Note that memory is guaranteed to be sufficiently aligned for any object of the requested size on the current platform, which may be less than the maximal alignment guarantee afforded by global operator new. |
| Name | Description |
|---|---|
size_type | Alias for an unsigned integral type capable of representing the number of bytes in this platform's virtual address space. |
| Name | Description |
|---|---|
NewDeleteAllocator [constructor] | Create a ("stateless") new-delete-allocator object that wraps the global native operator new and operator delete functions in order to supply memory via the Allocator protocol. Note that all objects of this class share the same underlying resource; hence, this constructor should generally not be invoked directly by clients; instead, consider using the static singleton or allocator (factory) methods, or -- better -- the appropriate ones in Default (see bslma_default for more information). |
~NewDeleteAllocator [destructor] [virtual] | Destroy this allocator object. Note that destroying this allocator has no effect on any outstanding allocated memory. |
operator= | |
allocate | Return a newly allocated block of memory of (at least) the specified positive size (in bytes). If size is 0, a null pointer is returned with no other effect. The alignment of the address returned is the maximum alignment for any fundamental, pointer, or enumerated type defined for this platform. The behavior is undefined unless 0 <= size. Note that global operator new is not called when size is 0 (in order to avoid having to acquire a lock, and potential contention in multi-threaded programs). |
deallocate | Return the memory block at the specified address back to this allocator. If address is 0, this function has no effect. The behavior is undefined unless address was allocated using this allocator object and has not already been deallocated. Note that global operator delete is not called when address is 0 (in order to avoid having to acquire a lock, and potential contention in multi-threaded programs). |
deleteObject | deleteObject overloads |
deleteObjectRaw | deleteObjectRaw overloads |
is_equal |
| Name | Description |
|---|---|
allocator | Return the address of the specified modifiable basicAllocator or, if basicAllocator is 0, the process-wide unique (see singleton) object of this class. Note that the behavior of this function is equivalent to the following expression: ` basicAllocator ? basicAllocator : &NewDeleteAllocator::singleton() ` Also note that if a NewDeleteAllocator object is supplied, it is owned by the class and must NOT be deleted. Finally note that this method should generally not be called directly by typical clients (see bslma_default for more information). |
singleton | Return a reference to a process-wide unique object of this class. The lifetime of this object is guaranteed to extend from the first call of this method until the program terminates. Note that this method should generally not be used directly by typical clients (see bslma_default for more information). |
throwBadAlloc | Throw std::bad_alloc if exceptions are enabled or abort the program otherwise. Derived classes and helper functions will typically call this function when they are unable to satisfy an allocation request. This function never returns. |
| Name | Description |
|---|---|
do_allocate [virtual] | Return a newly allocated block of memory of (at least) the specified positive bytes and having at least the specified alignment. Unless overriden in a derived class, the return value is this->allocate(bytes). If this allocator cannot return the requested number of bytes or cannot satisfy the alignment request, then it will throw a std::bad_alloc exception in an exception-enabled build, or else will abort the program in a non-exception build. Unless overriden in a derived class, this function will forward the allocation request to the allocate virtual function, padding bytes and adjusting the return value as necessary to ensure sufficient alignment. Note that if bytes is 0, the same non-null value will be returned every time. |
do_deallocate [virtual] | Return the memory block at the specified p address, having the specified bytes and specified alignment, back to this allocator. Unless overriden in a derived class, this function will forward the deallocation request to the deallocate virtual function, padding bytes and adjusting p as necessary to account for alignment values other than the natural alignment for an object of size bytes. The behavior is undefined unless address is a block allocated from this allocator object using the same bytes and alignment and not already deallocated. |
do_is_equal [virtual] | Return true if this allocator is equal to the specified other allocator, meaning (at least) that a memory block allocated by one can be deallocated by the other; otherwise return false. Unless overriden, this method returns this == &other. |