SplDoublyLinkedList::setIteratorMode()

(PHP 5 >= 5.3.0, PHP 7)

Sets the mode of iteration

说明

publicSplDoublyLinkedList::setIteratorMode(int $mode) : void

参数

$mode

There are two orthogonal sets of modes that can be set:

• The direction of the iteration (either one or the other):
  • SplDoublyLinkedList::IT_MODE_LIFO(Stack style)
  • SplDoublyLinkedList::IT_MODE_FIFO(Queue style)
• The behavior of the iterator (either one or the other):
  • SplDoublyLinkedList::IT_MODE_DELETE(Elements are deleted by the iterator)
  • SplDoublyLinkedList::IT_MODE_KEEP(Elements are traversed by the iterator)

The default mode is:SplDoublyLinkedList::IT_MODE_FIFO| SplDoublyLinkedList::IT_MODE_KEEP

返回值

没有返回值。

Despite the seeming unrelated-ness between the FIFO/LIFO and the KEEP/DELETE option pairs, in respect to the behavior of setIteratorMode they are in some way linked. Meaning, a second call to setIteratorMode will erase any previous settings even if they are from the other pair. This, coupled with the default settings for the object (SplDoublyLinkedList::IT_MODE_FIFO | SplDoublyLinkedList::IT_MODE_KEEP), means you have to be careful or you can run into trouble
Consider the following example:
<?php
$l = new SPLDoublyLinkedList();
$l->setIteratorMode(SplDoublyLinkedList::IT_MODE_DELETE);
$l->setIteratorMode(SplDoublyLinkedList::IT_MODE_LIFO);
$mode = $l->getIteratorMode();
var_dump("MODE: $mode");
var_dump("MODE CHECKS");
var_dump(($mode & SplDoublyLinkedList::IT_MODE_LIFO) == SplDoublyLinkedList::IT_MODE_LIFO);
var_dump(($mode & SplDoublyLinkedList::IT_MODE_FIFO) == SplDoublyLinkedList::IT_MODE_FIFO);
var_dump(($mode & SplDoublyLinkedList::IT_MODE_DELETE) == SplDoublyLinkedList::IT_MODE_DELETE);
var_dump(($mode & SplDoublyLinkedList::IT_MODE_KEEP) == SplDoublyLinkedList::IT_MODE_KEEP);
$l->push('A');
$l->push('B');
$l->push('C');
$l->push('D');
$l->rewind();
var_dump("Traversing");
var_dump($l->isEmpty());
var_dump($l->count());
var_dump($l->current());
$l->next();
var_dump($l->count());
var_dump($l->current());
$l->next();
var_dump($l->count());
var_dump($l->current());
$l->next();
var_dump($l->count());
var_dump($l->current());
$l->next();
var_dump($l->count());
var_dump($l->isEmpty());
?>
Which outputs the following:
#############################
string(7) "MODE: 2"
string(11) "MODE CHECKS"
bool(true) #LIFO (ok)
bool(true) #FIFO (umm...wait a minute)
bool(false)#DELETE (houston... wtf)
bool(true) #KEEP (ok, where's the camera hidden)
string(10) "Traversing"
bool(false)
int(4)
string(1) "D"
int(4)
string(1) "C"
int(4)
string(1) "B"
int(4)
string(1) "A"
int(4)
bool(false)
#############################
Basically, you should just check the non-zero flags (LIFO(2) and DELETE(1)). Since it's an either/or situation within the pairs, this should be able to help you figure out the separate mode pieces an instance has been set to.
example:
<?php
$l = new SPLDoublyLinkedList();
$l->setIteratorMode(SplDoublyLinkedList::IT_MODE_FIFO | SplDoublyLinkedList::IT_MODE_DELETE);
$mode = $l->getIteratorMode();
$isLIFO = ($mode & SplDoublyLinkedList::IT_MODE_LIFO) == SplDoublyLinkedList::IT_MODE_LIFO;
$isDELETE = ($mode & SplDoublyLinkedList::IT_MODE_DELETE) == SplDoublyLinkedList::IT_MODE_DELETE;
?>
hope this helps someone.

Usage of different Iterator Mode
<?php
$doubly=new SplDoublyLinkedList();
$doubly->push(array('name'=>'Naruto'));
$doubly->push(array('name'=>'Sakura'));
$doubly->push(array('name'=>'Neji'));
$doubly->push(array('name'=>'Sasuke'));
var_dump($doubly);
echo '<br/> FIFO Traversing<br/>';
$doubly->setIteratorMode(SplDoublyLinkedList::IT_MODE_FIFO | SplDoublyLinkedList::IT_MODE_KEEP);
$doubly->rewind();
foreach($doubly as $key=>$value)
{
  echo '<br/>Traversed:'.$key.' '.$value['name'];
}
echo '<br/>LIFO Traversing - Keep mode <br/>';
$doubly->setIteratorMode(SplDoublyLinkedList::IT_MODE_LIFO | SplDoublyLinkedList::IT_MODE_KEEP);
$doubly->rewind();
foreach($doubly as $key=>$value)
{
  echo '<br/>Traversed:'.$key.' '.$value['name'];
}
echo '<br/>LIFO Traversing - Delete mode <br/>';
$doubly->setIteratorMode(SplDoublyLinkedList::IT_MODE_LIFO | SplDoublyLinkedList::IT_MODE_DELETE);
$doubly->rewind();
foreach($doubly as $key=>$value)
{
  if($key == 2) break;
  echo '<br/>Traversed:'.$key.' '.$value['name'];
}
var_dump($doubly);
?>
Output:
FIFO Traversing
Traversed:0 Naruto
Traversed:1 Sakura
Traversed:2 Neji
Traversed:3 Sasuke
LIFO Traversing - Keep mode 
Traversed:3 Sasuke
Traversed:2 Neji
Traversed:1 Sakura
Traversed:0 Naruto
LIFO Traversing - Delete mode 
Traversed:3 Sasuke
object(SplDoublyLinkedList)#1 (2) {
 ["flags":"SplDoublyLinkedList":private]=>
 int(3)
 ["dllist":"SplDoublyLinkedList":private]=>
 array(3) {
  [0]=>
  array(1) {
   ["name"]=>
   string(6) "Naruto"
  }
  [1]=>
  array(1) {
   ["name"]=>
   string(6) "Sakura"
  }
  [2]=>
  array(1) {
   ["name"]=>
   string(4) "Neji"
  }
 }
}