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pw::allocator::NullAllocator Class Reference
pw_allocator » Concrete allocators

Overview

A memory allocator that always fails to allocate memory.

A null allocator may be useful as part of a larger framework if allocation should be disallowed under certain circumstances. For example, a function that returns different allocators based on an input parameter may return a null allocator when given an invalid or unsupported parameter value.

Inheritance diagram for pw::allocator::NullAllocator:
pw::Allocator pw::Deallocator

Static Public Attributes

static constexpr Capabilities kCapabilities = 0
 

Private Member Functions

void * DoAllocate (Layout) override
 
void DoDeallocate (void *) override
 
void DoDeallocate (void *ptr, Layout) override
 

Friends

NullAllocator & GetNullAllocator ()
 Returns a reference to the NullAllocator singleton.
 

Additional Inherited Members

- Public Types inherited from pw::Deallocator
using Capabilities = allocator::Capabilities
 
using Capability = allocator::Capability
 
using Layout = allocator::Layout
 
- Public Member Functions inherited from pw::Allocator
void * Allocate (Layout layout)
 
template<typename T , int &... kExplicitGuard, typename... Args>
std::enable_if_t<!std::is_array_v< T >, T * > New (Args &&... args)
 
template<typename T , int &... kExplicitGuard, typename ElementType = std::remove_extent_t<T>, std::enable_if_t< is_bounded_array_v< T >, int > = 0>
ElementType * New ()
 
template<typename T , int &... kExplicitGuard, typename ElementType = std::remove_extent_t<T>, std::enable_if_t< is_unbounded_array_v< T >, int > = 0>
ElementType * New (size_t count)
 
template<typename T , int &... kExplicitGuard, typename ElementType = std::remove_extent_t<T>, std::enable_if_t< is_unbounded_array_v< T >, int > = 0>
ElementType * New (size_t count, size_t alignment)
 Constructs an alignment-byte aligned array of count objects.
 
template<typename T >
T * NewArray (size_t count)
 
template<typename T >
T * NewArray (size_t count, size_t alignment)
 
template<typename T , int &... kExplicitGuard, std::enable_if_t<!std::is_array_v< T >, int > = 0, typename... Args>
UniquePtr< T > MakeUnique (Args &&... args)
 
template<typename T , int &... kExplicitGuard, std::enable_if_t< is_unbounded_array_v< T >, int > = 0>
UniquePtr< T > MakeUnique (size_t size)
 
template<typename T , int &... kExplicitGuard, std::enable_if_t< is_unbounded_array_v< T >, int > = 0>
UniquePtr< T > MakeUnique (size_t size, size_t alignment)
 
template<typename T , int &... kExplicitGuard, std::enable_if_t< is_bounded_array_v< T >, int > = 0>
UniquePtr< T > MakeUnique ()
 
template<typename T >
UniquePtr< T[]> MakeUniqueArray (size_t size)
 
template<typename T >
UniquePtr< T[]> MakeUniqueArray (size_t size, size_t alignment)
 
template<typename T , int &... kExplicitGuard, std::enable_if_t<!std::is_array_v< T >, int > = 0, typename... Args>
SharedPtr< T > MakeShared (Args &&... args)
 
template<typename T , int &... kExplicitGuard, std::enable_if_t< is_unbounded_array_v< T >, int > = 0>
SharedPtr< T > MakeShared (size_t size)
 
template<typename T , int &... kExplicitGuard, std::enable_if_t< is_unbounded_array_v< T >, int > = 0>
SharedPtr< T > MakeShared (size_t size, size_t alignment)
 
template<typename T , int &... kExplicitGuard, std::enable_if_t< is_bounded_array_v< T >, int > = 0>
SharedPtr< T > MakeShared ()
 
bool Resize (void *ptr, size_t new_size)
 
bool Resize (void *ptr, Layout layout, size_t new_size)
 
void * Reallocate (void *ptr, Layout new_layout)
 
void * Reallocate (void *ptr, Layout old_layout, size_t new_size)
 
size_t GetAllocated () const
 
- Public Member Functions inherited from pw::Deallocator
constexpr const Capabilities & capabilities () const
 
constexpr bool HasCapability (Capability capability) const
 Returns whether a given capability is enabled for this object.
 
void Deallocate (void *ptr)
 
void Deallocate (void *ptr, Layout layout)
 
template<typename ElementType >
void DeleteArray (ElementType *ptr, size_t count)
 
StatusWithSize GetCapacity () const
 
bool IsEqual (const Deallocator &other) const
 
template<typename T , int &... kExplicitGuard, std::enable_if_t<!std::is_array_v< T >, int > = 0>
void Delete (T *ptr)
 
template<typename T , int &... kExplicitGuard, typename ElementType = std::remove_extent_t<T>, std::enable_if_t< is_bounded_array_v< T >, int > = 0>
void Delete (ElementType *ptr)
 
template<typename T , int &... kExplicitGuard, typename ElementType = std::remove_extent_t<T>, std::enable_if_t< is_unbounded_array_v< T >, int > = 0>
void Delete (ElementType *ptr, size_t count)
 
- Protected Member Functions inherited from pw::Allocator
constexpr Allocator ()=default
 TODO(b/326509341): Remove when downstream consumers migrate.
 
constexpr Allocator (const Capabilities &capabilities)
 
- Protected Member Functions inherited from pw::Deallocator
constexpr Deallocator ()=default
 TODO(b/326509341): Remove when downstream consumers migrate.
 
constexpr Deallocator (const Capabilities &capabilities)
 
template<typename T , int &... kExplicitGuard, typename ElementType = std::remove_extent_t<T>, std::enable_if_t< is_unbounded_array_v< T >, int > = 0>
UniquePtr< T > WrapUnique (ElementType *ptr, size_t size)
 
- Static Protected Attributes inherited from pw::Deallocator
template<typename T >
static constexpr bool is_bounded_array_v
 
template<typename T >
static constexpr bool is_unbounded_array_v
 

Member Function Documentation

◆ DoAllocate()

void * pw::allocator::NullAllocator::DoAllocate ( Layout  )
inlineoverrideprivatevirtual

Allocates a block of memory with the specified size and alignment.

Returns nullptr if the allocation cannot be made, or the layout has a size of 0.

Parameters
[in]layoutDescribes the memory to be allocated.

Implements pw::Allocator.

◆ DoDeallocate() [1/2]

void pw::allocator::NullAllocator::DoDeallocate ( void *  )
inlineoverrideprivate

Releases a previously-allocated block of memory.

The given pointer must have been previously provided by this memory resource; otherwise the behavior is undefined.

Parameters
[in]ptrPointer to previously-allocated memory.

◆ DoDeallocate() [2/2]

void pw::allocator::NullAllocator::DoDeallocate ( void *  ptr,
Layout   
)
inlineoverrideprivate

Releases a previously-allocated block of memory.

The given pointer must have been previously provided by this memory resource; otherwise the behavior is undefined.

Parameters
[in]ptrPointer to previously-allocated memory.
The documentation for this class was generated from the following file: