README

Abstract base class that provides a Java-style Collection interface in PHP.

This class brings structured, type-safe, and object-oriented collection handling to PHP, inspired by Java's Collection framework. It extends ArrayObject and implements JsonSerializable and Psr\Container\ContainerInterface to offer modern PHP compatibility along with predictable, validated container behavior.

Subclasses must implement the protected validate($value): void method to define what values the collection accepts. Rejected values should throw an instance of InvalidArgumentException.

Key Features

• Enforces validation on all insertions via ::validate(mixed $value)
• Supports both sequential (list-style) and associative (map-style) arrays
• Implements ContainerInterface for ease of access and consistency
• Implements JsonSerializable for structured serialization of contents
• Offers utility methods similar to Java/JavaScript/TypeScript:
  • getFirst - get the first element in a collection
  • getLast - get the last element in a collection
  • getNth - get the nth element in a collection, index begins at 1
  • getKeys - get the keys for a map style collection
  • slice - get a new collection consisting of a slice of the current one
  • chunk - create multiple collections of a specific chunk size
  • filter - pass a callable to filter the elements of a collection
  • map - pass a callable to map the elements of a collection to a new collection
  • walk - use a callable to apply transformation to every member of a collection
  • reduce - reduce the elements of a collection to a single value
  • empty - empty the collection of all values
  • absorb - absorb the contents of a collection into another
  • renameKey - rename the key for a specified value in the collection

Example

namespace Foo\Bars;

use Foo\Bar;
use InvalidArgumentException;
use Subtext\Collections;

class Collection extends Collections\Collection
{
    protected function validate(mixed $value): void
    {
        if (!($value instanceof Bar)) {
            throw new InvalidArgumentException(sprintf(
                'Value added to collection must be an instance of %s',
                Bar::class
            ));
        }
    }
}