PHP Collection

PHP Collection library.

Based on J. M. Schmitt work, refactored and updated - now requires PHP 8.0. Updated with several useful methods like ::flatMap(), ::map(), ::foldLeft(), ::exists(), ::headOption(), ::lastOption(), ::tail() and e.t.c. Inspired by Scala collections. Added types.

Installation

PHP Collection can easily be installed via composer (in process)

composer require imunhatep/collection

or add it to your composer.json file.

Note

Collections can be seen as more specialized arrays for which certain contracts are guaranteed.

Supported Collections:

• Sequence

  • Keys: numerical, consequentially increasing, no gaps
  • Values: anything, duplicates allowed
  • Classes: Sequence, SortedSequence

• Map

  • Keys: strings or objects, duplicate keys not allowed
  • Values: anything, duplicates allowed
  • Classes: Map, LRUMap

• Set

  • Keys: not meaningful
  • Values: objects, or scalars, each value is guaranteed to be unique (see Set usage below for details)
  • Classes: Set

General Characteristics:

• Collections are mutable (new elements may be added, existing elements may be modified or removed). Specialized immutable versions may be added in the future though.
• Equality comparison between elements are always performed using the shallow comparison operator (===).
• Sorting algorithms are unstable, that means the order for equal elements is undefined (the default, and only PHP behavior).

Usage

Collection classes provide a rich API.

Sequence

    // Read Operations
    $seq = new Sequence([0, 2, 3, 2]);
    $seq->get(2); // int(3)
    $seq->all(); // [0, 2, 3, 2]

    $seq->head(); // Some(0)
    $seq->tail(); // Some(2)

    // Write Operations
    $seq = new Sequence([1, 5]);
    $seq->get(0); // int(1)
    
    $seq
      ->update(0, 4);
      ->get(0); // int(4)
    
    $seq
      ->remove(0)
      ->get(0); // int(5)

    $seq = new Sequence([1, 4]);
    $seq
      ->add(2)
      ->all(); // [1, 4, 2]
    
    $seq
      ->addAll([4, 5, 2])
      ->all(); // [1, 4, 2, 4, 5, 2]

    // Sort
    $seq = new Sequence([0, 5, 4, 2]);
    $seq
      ->sortWith(fn($a, $b) => ($a - $b));
      ->all(); // [0, 2, 4, 5]

Maps

    // Read Operations
    $map = new Map(['foo' => 'bar', 'baz' => 'boo']);
    $map->get('foo'); // Some('bar')
    $map->get('foo')->get(); // string('bar')
    $map->keys(); // ['foo', 'baz']
    $map->values(); // ['bar', 'boo']

    $map->headOption(); // Some(['key', 'value'])
    $map->head();       // null | ['key', 'value']
    $map->lastOption(); // Some(['key', 'value'])
    $map->last();       // null | ['key', 'value']
    
    $map->headOption()->getOrElse([]); // ['foo', 'bar']
    $map->lastOption()->getOrElse([]); // ['baz', 'boo']
    
    $map->tail();            // ['baz' => 'boo']

    iterator_to_array($map); // ['foo' => 'bar', 'baz' => 'boo']
    $map->all()              // ['foo' => 'bar', 'baz' => 'boo']

    // Write Operations
    $map = new Map();
    $map->set('foo', 'bar');
    $map->setAll(['bar' => 'baz', 'baz' => 'boo']);
    $map->remove('foo');

    // Sort
    $map->sortWith('strcmp');

    // Transformation
    $map->map(fn($k,$v) => ($value * 2));
    
    $map->flatMap(fn($k,$v) => (new Map())->set($k, $v * 2) );
    
    $map->foldLeft(SomeObject $s, fn($s, $k, $v) => $s->add([$k, $v * 2]))

Set

In a Set each value is guaranteed to be unique. The Set class supports objects, and scalars as value. Equality is determined via the following steps.

Equality of Scalars

Scalar are considered equal if ``$a === $b`` is true.

    class DateTimeHashable extends \DateTime implements HashableInterface
    {
        public function hash(): string
        {
            return $this->format("YmdP");
        }
    }
    
    $set = new Set();
    $set->add(new DateTimeHashable('today'));
    $set->add(new DateTimeHashable('today'));

    var_dump(count($set)); // int(1) -> the same date is not added twice

    foreach ($set as $date) {
        var_dump($date);
    }

    $set->all();
    $set->addSet($otherSet);
    $set->addAll($someElements);

    // Traverse
    $set->map(function($x) { return $x*2; });
    $set->flatMap(function($x) { return [$x*2, $x*4]; });