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Interface: StructDef

A struct described with defineStruct: packs a plain object into struct bytes and unpacks them back.

It is an AdvancedType, so it doubles as a dlopen argument or return type — its toBuffer is StructDef.pack and its fromBuffer is StructDef.unpack — and a struct is then passed and returned by value.

Extends​

Properties​

align​

readonly align: number

Alignment of the struct in bytes.

ffiType​

readonly ffiType: SimpleType

Inherited from​

AdvancedType.ffiType

ffiTypeStruct​

readonly ffiTypeStruct: SimpleType<StructValues>

Inherited from​

AdvancedType.ffiTypeStruct

fields​

readonly fields: [string, object][]

The fields as [ name, type ] pairs, with each type resolved to a type object — a string alias appears as the types entry it names, and a [ elementType ] field as an object whose name is '<element>[]'. Fields dropped by a StructFieldOptions.condition are not listed.

name​

readonly name: string

Inherited from​

AdvancedType.name

size​

readonly size: number

Size of the struct in bytes, padding included.

Overrides​

AdvancedType.size

Methods​

describe()​

describe(): StructFieldInfo[]

The layout, field by field: the offsets, sizes and type names libffi computed. The place to look when a struct does not agree with C.

Returns​

StructFieldInfo[]

fromBuffer()​

fromBuffer(buffer, ctx?): T

Parameters​

buffer​

Uint8Array

ctx?​

Returns​

T

Inherited from​

AdvancedType.fromBuffer

pack()​

pack(obj): Uint8Array

Struct bytes for obj, size bytes long.

Parameters​

obj​

StructValues

Returns​

Uint8Array

packListInto()​

packListInto(objects, buf, offset?): void

Pack a run of structs back to back into a buffer the caller owns, without a buffer per element. Padding between fields keeps whatever the buffer already held.

Parameters​

objects​

readonly StructValues[]

The structs to write.

buf​

ArrayBuffer | ArrayBufferView<ArrayBufferLike>

Buffer to write into; must have room for all of them.

offset?​

number

Byte offset to start at.

Returns​

void

toBuffer()​

toBuffer(data, ctx?): Uint8Array

Parameters​

data​

T

ctx?​

Returns​

Uint8Array

Inherited from​

AdvancedType.toBuffer

unpack()​

unpack(buf): StructValues

The object buf holds. Reads the struct at offset 0.

Parameters​

buf​

ArrayBuffer | ArrayBufferView<ArrayBufferLike>

Returns​

StructValues

unpackInto()​

unpackInto<T>(buf, target, offset?): T & StructValues

Write the fields into an object the caller owns and return it, rather than allocating a result object. Only the struct's own fields are assigned; anything else on target is left alone.

Type Parameters​

T​

T extends object

Parameters​

buf​

ArrayBuffer | ArrayBufferView<ArrayBufferLike>

Bytes to read.

target​

T

Object to assign the fields to.

offset?​

number

Byte offset of the struct within buf.

Returns​

T & StructValues

unpackList()​

unpackList(buf, count): StructValues[]

Unpack count structs packed back to back, from offset 0.

Parameters​

buf​

ArrayBuffer | ArrayBufferView<ArrayBufferLike>

count​

number

Returns​

StructValues[]