SplDoublyLinkedList::setIteratorMode

(PHP 5 >= 5.3.0)

SplDoublyLinkedList::setIteratorMode — Sets the mode of iteration

说明

public void SplDoublyLinkedList::setIteratorMode ( int $mode )

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。

用户评论:

[#1] gregorypatmore at gmail dot com [2011-12-11 11:15:01]

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.

[#2] pritiatwork at gmail dot com [2011-09-07 23:39:18]

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"
    }
  }
}