SplDoublyLinkedList::setIteratorMode()
(PHP 5 >= 5.3.0, PHP 7)
Sets the mode of iteration
说明
public SplDoublyLinkedList::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
- The direction of the iteration (either one or the other):
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" } } }