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:

Static Public Attributes
static constexpr Capabilities	kCapabilities = 0

Protected Member Functions
void *	DoAllocate (Layout layout) override

void	DoDeallocate (void *ptr) override

Protected Member Functions inherited from pw::allocator::AbstractAllocator
constexpr	AbstractAllocator (Capabilities capabilities)

bool	DoResize (void *ptr, size_t new_size) override

size_t	DoGetAllocated () const override

std::optional< Fragmentation >	DoMeasureFragmentation () const override
	Returns fragmentation information for the allocator's memory region.

Result< Layout >	DoGetInfo (InfoType, const void *) const override

Protected Member Functions inherited from pw::Allocator
constexpr	Allocator ()=default
	TODO(b/326509341): Remove when downstream consumers migrate.

constexpr	Allocator (const Capabilities &capabilities)

virtual void *	DoAllocate (Layout layout)=0

virtual bool	DoResize (void *ptr, size_t new_size)

virtual void *	DoReallocate (void *ptr, Layout new_layout)

virtual size_t	DoGetAllocated () const

virtual std::optional< Fragmentation >	DoMeasureFragmentation () const
	Returns fragmentation information for the allocator's memory region.

Protected Member Functions inherited from pw::Deallocator
constexpr	Deallocator ()=default
	TODO(b/326509341): Remove when downstream consumers migrate.

constexpr	Deallocator (const Capabilities &capabilities)

Result< Layout >	GetInfo (InfoType info_type, const void *ptr) const

Result< Layout >	GetRequestedLayout (const void *ptr) const

Result< Layout >	GetUsableLayout (const void *ptr) const

Result< Layout >	GetAllocatedLayout (const void *ptr) const

bool	Recognizes (const void *ptr) const

virtual void	DoDeallocate (void *ptr)=0

virtual Result< Layout >	DoGetInfo (InfoType, const void *) const

Additional Inherited Members
Public Types inherited from pw::Allocator
using	Fragmentation = allocator::Fragmentation

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, std::enable_if_t<!std::is_array_v< T >, int > = 0, typename... Args>
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 , int &... kExplicitGuard, std::enable_if_t<!std::is_array_v< T >, int > = 0, typename... Args>
UniquePtr< T >	MakeUnique (Args &&... args)

template<typename T , std::enable_if_t< is_unbounded_array_v< T >, int > = 0>
UniquePtr< T >	MakeUnique (size_t size)

template<typename T , std::enable_if_t< is_unbounded_array_v< T >, int > = 0>
UniquePtr< T >	MakeUnique (size_t size, size_t alignment)

template<typename T , std::enable_if_t< is_bounded_array_v< T >, int > = 0>
UniquePtr< T >	MakeUnique ()

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 , std::enable_if_t< is_unbounded_array_v< T >, int > = 0>
SharedPtr< T >	MakeShared (size_t size)

template<typename T , std::enable_if_t< is_unbounded_array_v< T >, int > = 0>
SharedPtr< T >	MakeShared (size_t size, size_t alignment)

template<typename T , std::enable_if_t< is_bounded_array_v< T >, int > = 0>
SharedPtr< T >	MakeShared ()

bool	Resize (void *ptr, size_t new_size)

void *	Reallocate (void *ptr, Layout new_layout)

size_t	GetAllocated () const

std::optional< Fragmentation >	MeasureFragmentation () const
	Returns fragmentation information for the allocator's memory region.

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)

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 Types inherited from pw::Deallocator
enum class	InfoType { kRequestedLayoutOf , kUsableLayoutOf , kAllocatedLayoutOf , kCapacity , kRecognizes }

Static Protected Member Functions inherited from pw::Deallocator
static Result< Layout >	GetInfo (const Deallocator &deallocator, InfoType info_type, const void *ptr)

static Result< Layout >	GetRequestedLayout (const Deallocator &deallocator, const void *ptr)

static Result< Layout >	GetUsableLayout (const Deallocator &deallocator, const void *ptr)

static Result< Layout >	GetAllocatedLayout (const Deallocator &deallocator, const void *ptr)

static bool	Recognizes (const Deallocator &deallocator, const void *ptr)

Static Protected Attributes inherited from pw::Deallocator
template<typename T >
static constexpr bool	is_bounded_array_v = ::pw::is_bounded_array_v<T>

template<typename T >
static constexpr bool	is_unbounded_array_v = ::pw::is_unbounded_array_v<T>

Member Function Documentation

◆ DoAllocate()

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

inlineoverrideprotectedvirtual

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] layout Describes the memory to be allocated.

Implements pw::Allocator.

◆ DoDeallocate()

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

inlineoverrideprotectedvirtual

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] ptr Pointer to previously-allocated memory.

Implements pw::Deallocator.

The documentation for this class was generated from the following file:

pw_allocator/public/pw_allocator/null_allocator.h

Overview

Static Public Attributes

Protected Member Functions

Additional Inherited Members

Member Function Documentation

◆ DoAllocate()

◆ DoDeallocate()