数据结构
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The SplObjectStorage class

(PHP 5 >= 5.3.0)

简介

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.

类摘要

SplObjectStorage implements Countable , Iterator , Traversable , Serializable , ArrayAccess {
/* 方法 */
public void addAll ( SplObjectStorage $storage )
public void attach ( object $object [, mixed $data = NULL ] )
public bool contains ( object $object )
public int count ( void )
public object current ( void )
public void detach ( object $object )
public string getHash ( string $object )
public mixed getInfo ( void )
public int key ( void )
public void next ( void )
public bool offsetExists ( object $object )
public mixed offsetGet ( object $object )
public void offsetSet ( object $object [, mixed $data = NULL ] )
public void offsetUnset ( object $object )
public void removeAll ( SplObjectStorage $storage )
public void removeAllExcept ( SplObjectStorage $storage )
public void rewind ( void )
public string serialize ( void )
public void setInfo ( mixed $data )
public void unserialize ( string $serialized )
public bool valid ( void )
}

范例

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));
?>

以上例程会输出：

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]);
}
?>

以上例程会输出：

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

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数据结构
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PHP手册 - N: The SplObjectStorage class

用户评论:

inwebo at gmail dot fr (29-Feb-2012 07:01)

I needed to merge SplObjectStorages.
<?php
// As an object set
$SplObjectStorage_1 = new SplObjectStorage();

$object1 = new StdClass;
$object1->attr = 'obj 1';
$object2 = new StdClass;
$object2->attr = 'obj 2';
$object3 = new StdClass;
$object3->attr = 'obj 3';

$SplObjectStorage_1->attach($object1);
$SplObjectStorage_1->attach($object2);
$SplObjectStorage_1->attach($object3);

// Another one object set
$SplObjectStorage_2 = new SplObjectStorage();

$object4 = new StdClass;
$object4->attr = 'obj 4';
$object5 = new StdClass;
$object5->attr = 'obj 5';
$object6 = new StdClass;
$object6->attr = 'obj 6';

$SplObjectStorage_2->attach($object4);
$SplObjectStorage_2->attach($object5);
$SplObjectStorage_2->attach($object6);

/**
 * Merge SplObjectStorage
 *
 * @param how many SplObjectStorage params as you want
 * @return SplObjectStorage
 */
function mergeSplObjectStorage() {
   
    $buffer   = new SplObjectStorage();

    if( func_num_args() > 0  ) {
        $args = func_get_args();
        foreach ($args as $objectStorage) {
            foreach($objectStorage as $object) {
                if(is_object( $object ) ) {
                    $buffer->attach($object);
                }
            }
        }
    }
    else{
        return FALSE;
    }
    return $buffer;
}

$merge = mergeSplObjectStorage($SplObjectStorage_1, $SplObjectStorage_2);

?>
<?php
echo $merge->count();
?>
Will output :
6

<?php
$merge->rewind();
while($merge->valid()) {
    $object = $merge->current();
    var_dump($object);
    $merge->next();
}
?>
Will ouput :
object(stdClass)#2 (1) {
  ["attr"]=>
  string(5) "obj 1"
}
object(stdClass)#3 (1) {
  ["attr"]=>
  string(5) "obj 2"
}
object(stdClass)#4 (1) {
  ["attr"]=>
  string(5) "obj 3"
}
object(stdClass)#6 (1) {
  ["attr"]=>
  string(5) "obj 4"
}
object(stdClass)#7 (1) {
  ["attr"]=>
  string(5) "obj 5"
}
object(stdClass)#8 (1) {
  ["attr"]=>
  string(5) "obj 6"
}

My two cents.

Hayley Watson (04-Feb-2012 08:16)

As an iterator, SplObjectStorage traverses the _keys_ of the map (the $o1, $o2 of Example 2) rather than the values. To retrieve each of those in turn requires an additional lookup:

<?php
// As a map from objects to data
$s = new SplObjectStorage();

$o1 = (object)array('a'=>1);
$o2 = (object)array('b'=>2);
$o3 = (object)array('c'=>3);

$s[$o1] = "data for object 1";
$s[$o2] = array(1,2,3);

foreach($s as $i => $key)
{
    echo "Entry $i:\n"; // You get a numeric index
    var_dump($key, $s[$key]);
    echo "\n";
}
?>

This makes sense when you use an SplObjectStorage as a set, since in that case all of the "values" are null.

Jan Walther (30-Jun-2011 02:57)

I rewrote some scripts and changed object storage with arrays to SplObjectStorage. At some point I needed support of array_rand() but I did not find a function to return a random attached object of an SplObjectStorage object.

So here is my solution for random access to SplObjectStorage:

<?php
$o1 = new StdClass;
$o2 = new StdClass;
$s = new SplObjectStorage;
$s->attach($o1);
$s->attach($o2);

$random = rand(0,$s->count()-1);
$s->rewind();
for($i=0;$i<$random;$i++) {
  $s->next();
}
var_dump($s->current());
?>

Robertas at pobox com (31-Jan-2010 07:13)

PHP 5.2.x and lower doesn't implement ArrayAccess in SplObjectStorage - it is only implemented starting from PHP 5.3

randallgirard at hotmail dot com (14-Dec-2009 08:01)

I have two things to note about SplObjectStorage:

#1: A reference to the object itself is stored (not just a hash to compare against the object) and it must be removed before the object is destroyed and the destructor is executed.

#2: SplObjectStorage::rewind() MUST be called to initiate the iterator and before SplObjectStorage::current() will return an object (and I think the only way to retrieve an object?) rather than automatically starting at the first element as I expected it to, like an array for example. This assumption is based on SplObjectStorage::current() returning NULL until SplObjectStorage::rewind() is called once the objects are contained. As a note, always use REWIND before iterating through or fetching objects.

<?php

class foo {
    public function __destruct() {
        print("--- DESTRUCTOR FIRED!!<br />\r\n");
    }
}

# Create object and storage
$bar = new foo();
$s = new SplObjectStorage();

# Rewind early just as a test
$s->rewind();

# attach the object
$s->attach($bar, array('test'));

# Unset the object; destructor does NOT fire
unset($bar);
print("Object has been unset<br />\r\n");

# First demonstrate that REWIND must be called to initialize the iterator
$obj = $s->current();
var_dump($obj);
print("- Note the NULL (from \$s->current())<br />\r\n");

# Initialize, and then detach the current (and only) object
$s->rewind();
$s->detach( $s->current() );

# The destructor should NOW execute

?>

Output:

Object has been unset
NULL - Note the NULL (from $s->current())
--- DESTRUCTOR FIRED!!