aeviiq / collection

A library that provides strict typed collections in PHP.

Aeviiq PHP Typed Collections

Why

To provide an easy way to ensure type safety on collections/arrays and provide useful custom methods for object collections, as seen in the example below.

Installation

composer require aeviiq/collection

Declaration

/**
 * @extends ObjectCollection<int, Foo>
 *
 * @method \ArrayIterator|Foo[] getIterator()
 * @method Foo|null first()
 * @method Foo|null last()
 */
final class FooCollection extends ObjectCollection
{
    public function filterReleasedBefore(\DateTimeInterface $dateTime): FooCollection
    {
        return $this->filter(static function (Foo $foo) use ($dateTime): bool {
            return $foo->getReleaseDate() < $dateTime;
        });
    }

    public function filterActives(): FooCollection
    {
        return $this->filter(static function (Foo $foo): bool {
            return $foo->isActive();
        });
    }
    
    protected function allowedInstance(): string
    {
        return Foo::class;
    }
}

Usage

// Useful custom methods for ObjectCollections:
$fooCollection = new FooCollection([$foo1, $foo2]);
$result = $fooCollection->filterReleasedBefore(new DateTime('now'))->filterActives();

// Basic type collections that are provided
$intCollection = new IntCollection([1, 2]);
$intCollection->append(3);

$intCollection = new IntCollection([1, '2']); // InvalidArgumentException thrown
$intCollection->append('3');  // InvalidArgumentException thrown

collection's Issues

Improve index to property name and add unit test for it.

• Ensure a valid index is created in all situations.

Generics for Collection functions

It would be nice to have a @template annotation for the default functions (first, last, getIterator and filter) and maybe more, so static code analysis tools like php-stan will understand the return type.

Add the possiblity to make a collection immutable.

• Will be a new classes.

PHP 8 support

Create an abstract test case for the abstract collection implementation.

Merge method could cause duplicate values

The current merge method, works as the default array_merge for all collection types, except the object collection. In the object collection, this will create a unique key, without checking the values. This could result in duplicate values, which would make no sense.

To solve this, it might make most sense to make it so that a merge will cause all unique values to be the result of the merge. This would also change the current behavior of the int, float and string collections.

Go back to using ArrayObject for v2.0

In order to use ArrayObject from spl again, a bug which occurs when using DeepCopy, needs to be fixed.

Fix psalm and phpstan annotations.

Known issues:

• CollectionInterface::merge()
• psalm-extends and psalm-implements should be extends and implements.

Refactor object collection to solve the deep clone bug itself.

Solution to use the prefixed memory hash for both serialization and (deep) cloning: the internal elements can be rebuild using the newly assigned memory hashes in both calls. In case this works, all methods that can append an element to the collection, can use these hashes instead.

Refactor internals to reduce code pollution.

ArrayCollection map function in ObjectCollection

The object collection inherits a map function from the ArrayCollection. This function returns a static version of itself with the mapped values. When using this method on an ObjectCollection it expects that it can construct the same collection as which the function is called on with the mapped values. This is most likely not possible since the map function is probably used to map values from one thing to another, i.e: from objects to integers.

Example

class FooCollection extends ObjectCollection {
    protected function allowedInstance(): string
    {
        return Foo::class;
    }
}

class Foo {
    public $id;

    public function __construct(int $fooId) {
        $this->id = $fooId;
    }
}

$collection = new FooCollection(new Foo(1), new Foo(2), new Foo(3));
$collection->map(function (Foo $foo) {
    return $foo->id; // returning the id of foo (integer)
}); // Fails because it cannot construct a FooCollection with an integer array

Unit tests for the float collection.

Unit tests for the int collection.

Unit Tests

Removing element within foreach causes unexpected behaviour

$fooCollection = new FooCollection(); // extends ObjectCollection

$fooCollection->count(); // 5

foreach ($fooCollection as $index => $foo) {
  var_dump($index);
  if ($this->someCondition()) {
    $fooCollection->remove($foo);
  }
}

var_dump() is only called 3 times instead of the expected 5 times.
It works as expected when looping over $fooCollection->toArray() instead.

BooleanCollection, combined with the reset(), end(), etc. could give wrong results.

Add a copy method

Improve PHPDoc for getIterator

The '@method \Traversable|float[] getIterator' annotation should contain the ArrayIterator.

Add method call on construct, to do specific sorting or validation for immutables.

DeepCopy combined with the storage of ArrayObject causes referential bug.

When an object containing an implementation of AbstractObjectCollection, gets copied using myclabs/deep-copy this causes a referential bug.

This does not occur in any version below 2.0.

exchangeArray wrong return type and missing in interface.

Use array<key, value> doc-comments instead of type[] when expecting an array

In some cases Collection|mixed[] is used to type a parameter to contain either an array or an instance of the Collection class. This however leads to some problems when using PHPStan. When the type[] format is used in combination with a class that implements the IteratorAggregate interface (like the Collection), the type will be parsed to Collection&iterator<type>. For more information see phpstan/phpstan#1988. An example of this type definition can be found on Collection::merge($input).

Add immutable collections for native types.

e.g.: ImmutableStringCollection, ImmutableIntCollection, etc. including unit tests.