ReadonlyArrayList

Raxos\Collection\ReadonlyArrayList is the immutable counterpart of ArrayList. It exposes the same read and transformation operations, but any write through array access throws a CollectionImmutableException.

readonly class ReadonlyArrayList implements
    ArrayListInterface,
    DebuggableInterface,
    JsonSerializable,
    SerializableInterface

Construction

__construct

public function __construct(array $data = [])

Creates a readonly list from a plain PHP array.

of

public static function of(iterable $items): static

Creates a new instance from any iterable, converting Traversable sources and reindexing list arrays.

Read and transformation operations

ReadonlyArrayList uses the same ArrayListable trait as ArrayList, so map, filter, reduce, first, last, chunk, groupBy, sort, slice, convertTo and the rest are all available. Each transformation returns a new ReadonlyArrayList; none mutate the receiver.

Reading through array access, count(), iteration, toArray() and jsonSerialize() all work exactly as on ArrayList.

Immutability

offsetSet and offsetUnset throw a CollectionImmutableException because the class is readonly. The append, prepend, pop and shift mutators from ArrayList are not part of ReadonlyArrayList.

<?php
declare(strict_types=1);

use Raxos\Collection\ReadonlyArrayList;
use Raxos\Collection\Error\CollectionImmutableException;

$list = ReadonlyArrayList::of([1, 2, 3]);

$doubled = $list->map(static fn(int $number): int => $number * 2); // new list

try {
    $list[] = 4; // throws
} catch (CollectionImmutableException $exception) {
    // The collection is immutable.
}

See also the array lists concept page.