nngn::alloc_block< H, T > Class Template Reference

Non-owning handle to an aggregate header and data block. More...

#include <block.h>

Collaboration diagram for nngn::alloc_block< H, T >:

Classes
struct	storage
	Underlying storage type. More...

Public Types
using	header_type = H
using	value_type = T

Public Member Functions
	alloc_block (void) noexcept=default
	Initializes a handle with no associated block.
constexpr storage *	data (void)
	Pointer to the block.
constexpr const storage *	data (void) const
	Pointer to the block.
constexpr header_type *	header (void)
	Pointer to the block header.
constexpr const header_type *	header (void) const
	Pointer to the block header.
constexpr value_type *	get (void)
	Pointer to the data block.
constexpr const value_type *	get (void) const
	Pointer to the data block.
void	realloc (std::size_t s)
	Reallocates the entire block.
void	free (void)
	Frees the block's memory.

Static Public Member Functions
static constexpr std::size_t	alloc_size (std::size_t n)
	Total size of an allocation for n elements.
static constexpr auto	from_storage_ptr (void *p)
	Constructs a handle to a pre-existing storage block.
static constexpr alloc_block	from_ptr (T *p)
	Offsets p to the beginning of the entire block.
static alloc_block	alloc (void)
	Allocates a block to contain exactly a T.
static alloc_block	alloc (std::size_t s)
	Allocates a block to contain s bytes of data.

Static Public Attributes
static constexpr std::size_t	data_offset
	Total size of an allocation for n elements.

Private Member Functions
	alloc_block (void *p_)
	Constructs from a pointer to the block.

Private Attributes
storage *	p = nullptr
	Pointer to the underlying storage, non-owning.

Static Private Attributes
static constexpr bool	both_trivial = trivial<H> && trivial<T>

Detailed Description

template<typename H, typename T = char>
class nngn::alloc_block< H, T >

Non-owning handle to an aggregate header and data block.

Primarily (but not necessarily) intended to be used in allocators. The underlying object is allocated as one block of memory. The handle provides accessors to both the header and data regions, as well as methods to reallocate and free the block.

Allocation functions are available if both types are trivial (since malloc, realloc, and free are used).

Template Parameters

H	The type stored in the header region.
T	The type stored in the data region. The default is char, which can either be a single byte or (more likely) used with alloc(size) to allocate a block of bytes. data() will the point to the beginning of the block.

Member Typedef Documentation

header_type

template<typename H , typename T = char>

using nngn::alloc_block< H, T >::header_type = H

value_type

template<typename H , typename T = char>

using nngn::alloc_block< H, T >::value_type = T

Constructor & Destructor Documentation

alloc_block() [1/2]

template<typename H , typename T = char>

nngn::alloc_block< H, T >::alloc_block ( void )

defaultnoexcept

Initializes a handle with no associated block.

alloc_block() [2/2]

template<typename H , typename T = char>

nngn::alloc_block< H, T >::alloc_block ( void * p_ )

inlineexplicitprivate

Constructs from a pointer to the block.

Member Function Documentation

alloc() [1/2]

template<typename H , typename T = char>

static alloc_block nngn::alloc_block< H, T >::alloc ( std::size_t s )

inlinestatic

Allocates a block to contain s bytes of data.

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alloc() [2/2]

template<typename H , typename T = char>

static alloc_block nngn::alloc_block< H, T >::alloc ( void )

inlinestatic

Allocates a block to contain exactly a T.

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alloc_size()

template<typename H , typename T >

std::size_t nngn::alloc_block< H, T >::alloc_size ( std::size_t n )

inlinestaticconstexpr

Total size of an allocation for n elements.

data() [1/2]

template<typename H , typename T = char>

storage * nngn::alloc_block< H, T >::data ( void )

inlineconstexpr

Pointer to the block.

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data() [2/2]

template<typename H , typename T = char>

const storage * nngn::alloc_block< H, T >::data ( void ) const

inlineconstexpr

Pointer to the block.

free()

template<typename H , typename T = char>

void nngn::alloc_block< H, T >::free ( void )

inline

Frees the block's memory.

Must be called explicitly.

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from_ptr()

template<typename H , typename T >

auto nngn::alloc_block< H, T >::from_ptr ( T * p )

inlinestaticconstexpr

Offsets p to the beginning of the entire block.

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from_storage_ptr()

template<typename H , typename T = char>

static constexpr auto nngn::alloc_block< H, T >::from_storage_ptr ( void * p )

inlinestaticconstexpr

Constructs a handle to a pre-existing storage block.

get() [1/2]

template<typename H , typename T = char>

value_type * nngn::alloc_block< H, T >::get ( void )

inlineconstexpr

Pointer to the data block.

get() [2/2]

template<typename H , typename T = char>

const value_type * nngn::alloc_block< H, T >::get ( void ) const

inlineconstexpr

Pointer to the data block.

header() [1/2]

template<typename H , typename T = char>

header_type * nngn::alloc_block< H, T >::header ( void )

inlineconstexpr

Pointer to the block header.

header() [2/2]

template<typename H , typename T = char>

const header_type * nngn::alloc_block< H, T >::header ( void ) const

inlineconstexpr

Pointer to the block header.

realloc()

template<typename H , typename T = char>

void nngn::alloc_block< H, T >::realloc ( std::size_t s )

inline

Reallocates the entire block.

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Member Data Documentation

both_trivial

template<typename H , typename T = char>

bool nngn::alloc_block< H, T >::both_trivial = trivial<H> && trivial<T>

staticconstexprprivate

data_offset

template<typename H , typename T = char>

std::size_t nngn::alloc_block< H, T >::data_offset

staticconstexpr

Initial value:

= [] {
        if constexpr(std::is_standard_layout_v<alloc_block::storage>)
            return offsetof(alloc_block::storage, data);
        else {
            struct S {
                alignas(header_type) char header[sizeof(header_type)];
                alignas(value_type) char data[sizeof(value_type)];
            };
            return offsetof(S, data);
        }
    }()

Total size of an allocation for n elements.

p

template<typename H , typename T = char>

storage* nngn::alloc_block< H, T >::p = nullptr

private

Pointer to the underlying storage, non-owning.

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

• src/utils/alloc/block.h