php - 反向SPL对象存储

Question

我有一个 SPLObjectStorage 对象，其中 Player 对象作为键，分数作为与其关联的信息。玩家对象按照从最高分到最低分的顺序添加到存储中，但我现在需要以相反的顺序迭代它们。

我还需要能够从指定的偏移量开始一直循环。我已经在下面弄清楚了这部分，我只是想不出一个好的方法来先扭转它。

// $players_group = new SPLObjectStorage()
// code to add Player and Score would go here
// above lines just for example

# NEED TO REVERSE ORDER PLAYERS GROUP HERE

$infinite_it = new InfiniteIterator($players_group);
$limit_it = new LimitIterator($infinite_it, $current_offset, $players_group->count());
foreach($limit_it as $p){
    // properly outputting from offset all the way around
    // but I need it in reverse order
}

我想避免遍历存储对象并将它们全部插入数组，然后执行 array_reverse，最后继续执行 foreach 循环。

Answer 1

SplObjectStorage 是一个键->值存储，并且 SplObjectStorage 中元素的“键”实际上是目的。排序和恢复需要您扩展和编写自己的实现，但我认为您应该考虑使用 SplStack

想象一下你的玩家等级

class Player {
    private $name;
    function __construct($name) {
        $this->name = $name;
    }
    function __toString() {
        return $this->name;
    }
}

使用SplStack

$group = new SplStack();
$group->push(new Player("Z"));
$group->push(new Player("A"));
$group->push(new Player("B"));
$group->push(new Player("C"));

echo "<pre>";
$infinite_it = new InfiniteIterator($group);
$limit_it = new LimitIterator($infinite_it, 0, 3); // get frist 3
foreach ( $limit_it as $p ) {
    echo ("$p");
}

如果您坚持使用 SplObjectStorage 那么您可以考虑自定义 ReverseArrayIterator

class ReverseArrayIterator extends ArrayIterator {
    public function __construct(Iterator $it) {
        parent::__construct(array_reverse(iterator_to_array($it)));
    }
}

用法

$group = new SplObjectStorage();
$group->attach(new Player("Z"));
$group->attach(new Player("A"));
$group->attach(new Player("B"));
$group->attach(new Player("C"));

echo "<pre>";
$infinite_it = new InfiniteIterator(new ReverseArrayIterator($group));
$limit_it = new LimitIterator($infinite_it, 0, 3); // get frist 3
foreach ( $limit_it as $p ) {
    echo ("$p");
}

两者都会输出

CBA //reversed