<?phpclass Node
{public $data;public $next;
}class LinkedList
{private $_head;private $_tail;private $_length;function init(){$this->_head = $this->_tail = null;$this->_length = 0;}function makeNode($data){$node = new Node();$node->data = $data;return $node;}function push($node){if ($this->_length == 0) {$this->_head = $this->_tail = $node;} else {$this->_tail->next = $node;$this->_tail = $node;}++$this->_length;}function pop(){if ($this->_length == 0) {return false;} elseif ($this->_length == 1) {$node = $this->makeNode($this->_tail->data);$this->_head = $this->_tail = null;--$this->_length;return $node;} elseif ($this->_length > 1) {$node = $this->makeNode($this->_tail->data);$secondTail = $this->_head;while ($secondTail->next != $this->_tail) {$secondTail = $secondTail->next;}$this->_tail = $secondTail;$this->_tail->next = null;--$this->_length;return $node;}}function unshift($node){if ($this->_length == 0) {$this->_head = $this->_tail = $node;} else {$node->next = $this->_head;$this->_head = $node;}++$this->_length;}function shift(){if ($this->_length == 0) {return false;} else {$node = $this->makeNode($this->_head->data);$this->_head = $this->_head->next;--$this->_length;return $node;}}function map($func){$node = $this->_head;$index = 0;while ($node != null) {$func($node->data, $index++);$node = $node->next;}}function reverse(){if ($this->_length == 0) return;$node = $this->_head;$next = $node->next;while ($next != null) {$third = $next->next;$next->next = $node;$node = $next;$next = $third;}$this->_tail = $this->_head;$this->_tail->next = null;$this->_head = $node;}function reverseRecursion(){if ($this->_length == 0) return;$head = $this->_head;$tail = $this->_tail;function reverse($next, $node, $tail){if ($node == $tail || $node == null) {return;} else {reverse($next->next, $next, $tail);$next->next = $node;}}reverse($head->next, $head, $tail);$this->_tail = $head;$this->_tail->next = null;$this->_head = $tail;}function getLength(){return $this->_length;}
}//test code
$linkedList = new LinkedList();
for ($i = 0; $i < 5; ++$i) {$node = $linkedList->makeNode(($i + 1) . ' apple');$linkedList->push($node);$node = $linkedList->makeNode(($i + 1) . ' banana');$linkedList->unshift($node);
}echo "linked list length is " . $linkedList->getLength() . " \n";
$linkedList->map(function ($val, $index) {echo "index is : $index \t value is : $val \n";
});echo "shift , value is : " . $linkedList->shift()->data . "\n";
echo "pop , value is : " . $linkedList->pop()->data . "\n";
echo "shift , value is : " . $linkedList->shift()->data . "\n";
echo "pop , value is : " . $linkedList->pop()->data . "\n";echo "linked list length is " . $linkedList->getLength() . " \n";
$linkedList->map(function ($val, $index) {echo "index is : $index \t value is : $val \n";
});$linkedList->reverse();
echo "linked list length is " . $linkedList->getLength() . " after reverse\n";
$linkedList->map(function ($val, $index) {echo "index is : $index \t value is : $val \n";
});$linkedList->reverseRecursion();
echo "linked list length is " . $linkedList->getLength() . " after reverse recursion\n";
$linkedList->map(function ($val, $index) {echo "index is : $index \t value is : $val \n";
});

linked list length is 10
index is : 0 value is : 5 banana
index is : 1 value is : 4 banana
index is : 2 value is : 3 banana
index is : 3 value is : 2 banana
index is : 4 value is : 1 banana
index is : 5 value is : 1 apple
index is : 6 value is : 2 apple
index is : 7 value is : 3 apple
index is : 8 value is : 4 apple
index is : 9 value is : 5 apple
shift , value is : 5 banana
pop , value is : 5 apple
shift , value is : 4 banana
pop , value is : 4 apple
linked list length is 6
index is : 0 value is : 3 banana
index is : 1 value is : 2 banana
index is : 2 value is : 1 banana
index is : 3 value is : 1 apple
index is : 4 value is : 2 apple
index is : 5 value is : 3 apple
linked list length is 6 after reverse
index is : 0 value is : 3 apple
index is : 1 value is : 2 apple
index is : 2 value is : 1 apple
index is : 3 value is : 1 banana
index is : 4 value is : 2 banana
index is : 5 value is : 3 banana
linked list length is 6 after reverse recursion
index is : 0 value is : 3 banana
index is : 1 value is : 2 banana
index is : 2 value is : 1 banana
index is : 3 value is : 1 apple
index is : 4 value is : 2 apple
index is : 5 value is : 3 apple