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Typed lists ​

The typed list variants extend ArrayList and constrain the type of value they hold. They implement ValidatedArrayListInterface, which adds a static validateItem() method. Whenever you build a typed list through of(), every item runs through validateItem() first, and an item of the wrong type raises a CollectionInvalidTypeException.

There are three built in variants:

  • StringArrayList: accepts only strings.
  • IntArrayList: accepts only integers.
  • NumberArrayList: accepts integers or floats.

Validation through of() ​

of() is the validating entry point. It walks the items and calls validateItem() for each one before constructing the list.

php
<?php
declare(strict_types=1);

use Raxos\Collection\StringArrayList;
use Raxos\Collection\Error\CollectionInvalidTypeException;

$valid = StringArrayList::of(['one', 'two', 'three']);

try {
    StringArrayList::of(['one', 2, 'three']); // 2 is not a string
} catch (CollectionInvalidTypeException $exception) {
    // Raxos\Collection\StringArrayList only accepts items of type string.
}

WARNING

Only of() validates. Constructing a typed list directly with new StringArrayList([...]) or writing through array access does not run validateItem(). Prefer of() when the input is not already known to be well typed.

StringArrayList ​

StringArrayList adds two helpers for gluing strings together.

php
use Raxos\Collection\StringArrayList;

$fruits = StringArrayList::of(['apples', 'pears', 'plums']);

$fruits->join();            // 'apples, pears, plums'
$fruits->join(' | ');       // 'apples | pears | plums'
$fruits->commaCommaAnd();   // 'apples, pears & plums'

IntArrayList ​

IntArrayList adds a sum() helper that returns an int.

php
use Raxos\Collection\IntArrayList;

$counts = IntArrayList::of([2, 4, 6]);

$counts->sum(); // 12

NumberArrayList ​

NumberArrayList accepts both integers and floats and returns a float|int from sum().

php
use Raxos\Collection\NumberArrayList;

$amounts = NumberArrayList::of([1.5, 2, 3.25]);

$amounts->sum(); // 6.75

Because the typed lists extend ArrayList, they inherit every operation from the array lists page, such as map, filter and sort. Note that those operations return an instance of the same typed class without re-running validation, so a map that changes the value type will not be caught until the next of().