Arrays

Repeat any field a fixed number of times, either with the [N] suffix on a type string or with the arraySize option on a descriptor.

Syntax

import { Struct } from '@remotex-labs/xstruct';

new Struct({
    a: 'Int32LE[8]',                          // suffix form
    b: { type: 'BigUInt64BE', arraySize: 4 }  // descriptor form
});

The array passed to toBuffer must contain exactly N elements.

Primitive arrays

const s = new Struct<{ values: number[] }>({ values: 'UInt16LE[4]' });

s.size; // 8, which is 4 elements of 2 bytes
s.toObject(s.toBuffer({ values: [ 1, 2, 3, 4 ] })).values; // [ 1, 2, 3, 4 ]

String arrays

Each element is encoded independently. Dynamic strings keep their own length prefix.

new Struct({
    tags: 'utf8[3]',      // 3 length-prefixed strings
    codes: 'ascii(4)[2]'  // 2 fixed 4-byte strings
});

See Strings.

Struct arrays

Repeat a nested struct with the arraySize option.

const Point = new Struct<{ x: number; y: number }>({ x: 'Int32LE', y: 'Int32LE' });

const Path = new Struct<{ points: { x: number; y: number }[] }>({
    points: { type: Point, arraySize: 3 } // 3 points
});

Embed a struct instance directly for a single value, and use { type, arraySize } for an array. See Nested Structs.

Sizing

A fixed array contributes N * elementSize to size. Arrays of dynamic strings extend the buffer beyond size; use the getDynamicOffset callback when reading them. See Working with Buffers.

See also

• Nested Structs
• Strings