# The SplObjectStorage class

(PHP 5 >= 5.1.0, PHP 7, PHP 8)

## Introduction

The SplObjectStorage class provides a map from objects to data or, by ignoring data, an object set. This dual purpose can be useful in many cases involving the need to uniquely identify objects.

## Class synopsis

class SplObjectStorage implements Countable, SeekableIterator, Serializable, ArrayAccess {
/* Methods */
public addAll(SplObjectStorage `$storage`): int
#[\Deprecated]
public attach(object `$object`, mixed `$info` = `null`): void
#[\Deprecated]
public contains(object `$object`): bool
public count(int `$mode` = `COUNT_NORMAL`): int
public current(): object
#[\Deprecated]
public detach(object `$object`): void
public getHash(object `$object`): string
public getInfo(): mixed
public key(): int
public next(): void
public offsetExists(object `$object`): bool
public offsetGet(object `$object`): mixed
public offsetSet(object `$object`, mixed `$info` = `null`): void
public offsetUnset(object `$object`): void
public removeAll(SplObjectStorage `$storage`): int
public removeAllExcept(SplObjectStorage `$storage`): int
public rewind(): void
public seek(int `$offset`): void
public serialize(): string
public setInfo(mixed `$info`): void
public unserialize(string `$data`): void
public valid(): bool
}

## Examples

Example #1 SplObjectStorage as a set

`<?php
// As an object set
$s = new SplObjectStorage();
$o1 = new stdClass;
$o2 = new stdClass;
$o3 = new stdClass;
$s->attach($o1);
$s->attach($o2);
var_dump($s->contains($o1));
var_dump($s->contains($o2));
var_dump($s->contains($o3));
$s->detach($o2);
var_dump($s->contains($o1));
var_dump($s->contains($o2));
var_dump($s->contains($o3));
?>`

The above example will output:

    bool(true)
    bool(true)
    bool(false)
    bool(true)
    bool(false)
    bool(false)

Example #2 SplObjectStorage as a map

`<?php
// As a map from objects to data
$s = new SplObjectStorage();
$o1 = new stdClass;
$o2 = new stdClass;
$o3 = new stdClass;
$s[$o1] = "data for object 1";
$s[$o2] = array(1,2,3);
if (isset($s[$o2])) {
var_dump($s[$o2]);
}
?>`

The above example will output:

    array(3) {
      [0]=>
      int(1)
      [1]=>
      int(2)
      [2]=>
      int(3)
    }

## Changelog

Version | Description
--- | ---
8.4.0 | Implement SeekableIterator, previously only Iterator was implemented.

## Table of Contents

- SplObjectStorage::addAll — Adds all objects from another storage
- SplObjectStorage::attach — Adds an object in the storage
- SplObjectStorage::contains — Checks if the storage contains a specific object
- SplObjectStorage::count — Returns the number of objects in the storage
- SplObjectStorage::current — Returns the current storage entry
- SplObjectStorage::detach — Removes an object from the storage
- SplObjectStorage::getHash — Calculate a unique identifier for the contained objects
- SplObjectStorage::getInfo — Returns the data associated with the current iterator entry
- SplObjectStorage::key — Returns the index at which the iterator currently is
- SplObjectStorage::next — Move to the next entry
- SplObjectStorage::offsetExists — Checks whether an object exists in the storage
- SplObjectStorage::offsetGet — Returns the data associated with an object
- SplObjectStorage::offsetSet — Associates data to an object in the storage
- SplObjectStorage::offsetUnset — Removes an object from the storage
- SplObjectStorage::removeAll — Removes objects contained in another storage from the current storage
- SplObjectStorage::removeAllExcept — Removes all objects except for those contained in another storage from the current storage
- SplObjectStorage::rewind — Rewind the iterator to the first storage element
- SplObjectStorage::seek — Seeks iterator to a position
- SplObjectStorage::serialize — Serializes the storage
- SplObjectStorage::setInfo — Sets the data associated with the current iterator entry
- SplObjectStorage::unserialize — Unserializes a storage from its string representation
- SplObjectStorage::valid — Returns if the current iterator entry is valid

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