PHP array with distinct elements (like Python set)

Question

Is there a version of the PHP array class where all the elements must be distinct like, for instance, sets in Python?

Answer 1

You can use a special class, or array_unique to filter the duplicates.

Answer 2

An array is an array, and for the most part yo can put anything into it. All keys must be unique. If you want to go and add a function that strips out duplicate values, that is very possible by simply doing a array_unique statement

Answer 3

Nope. You could fake it by using an associative array where the keys are the elements in the "set" and the values are ignored.

Answer 4

Here's a first-draft of an idea that could eventually work for what you want.

<?php

class DistinctArray implements IteratorAggregate, Countable, ArrayAccess
{
  protected $store = array();

  public function __construct( array $initialValues )
  {
    foreach ( $initialValues as $key => $value )
    {
      $this[$key] = $value;
    }
  }

  final public function offsetSet( $offset, $value )
  {
    if ( in_array( $value, $this->store, true ) )
    {
      throw new Exception( 'Values must be unique!' );
    }
    if ( null === $offset )
    {
      array_push( $this->store, $value );
    } else {
      $this->store[$offset] = $value;
    }
  }

  final public function offsetGet( $offset )
  {
    return $this->store[$offset];
  }

  final public function offsetExists( $offset )
  {
    return isset( $this->store[$offset] );
  }

  final public function offsetUnset( $offset )
  {
    unset( $this->store[$offset] );
  }

  final public function count()
  {
    return count( $this->store );
  }

  final public function getIterator()
  {
    return new ArrayIterator( $this->store );
  }
}

$test = new DistinctArray( array(
    'test' => 1
  , 'foo'  => 2
  , 'bar'  => 3
  , 'baz'  => '1'
  , 8      => 4
) );

try {
  $test[] = 5;
  $test[] = 6;
  $test['dupe'] = 1;
}
catch ( Exception $e )
{
  echo "Oops! ", $e->getMessage(), "<hr>";
}

foreach ( $test as $value )
{
  echo $value, '<br>';
}

Answer 5

For objects that are not integers and strings: SplObjectStorage

The SplObjectStorage class provides a map from objects to data or, by ignoring data, an object set.