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php Iterator-如何保存所有倒数第二的元素

recursive-datastructures spl iterator php

1

Spurious · 技术社区 · 11 年前

我不知所措。我在谷歌上搜索了好几个小时,阅读了php手册,但我无法找到解决方案。

我得到了以下数组结构:

[x] => Array
    (
        ...
                  [object_name_1] => Array
                      (
                          [db] => x
                          [form] => y
                          [value] => z
                      )

                  ...

                  [object_name_4] => Array
                      (
                          [db] => x
                          [form] => y
                          [value] => z
                      )
                  ...

                  [object_name_n] => Array
                      (
                          [db] => x
                          [form] => y
                          [value] => z
                      )
...
[y] => Array
    (
        ...
        [object_group_xyz] => Array
           (
                  [object_name_a] => Array
                      (
                          [db] => x
                          [form] => y
                          [value] => z
                      )

                  ...
           )
                  ...

                  [object_name_e] => Array
                      (
                          [db] => x
                          [form] => y
                          [value] => z
                      )
                  ...

                  [object_name_z] => Array
                      (
                          [db] => x
                          [form] => y
                          [value] => z
                      )

现在我的问题如下: 我想保存所有object_name_x数组。数组的深度未知,事实上,不同object_name_n对象的深度可以取决于同一数组。但它们总是最后一片叶子。

我该如何解决这个问题。据我所知,RecursiveIteratorIterator不可能只考虑倒数第二个对象。

我的输出应该是这样的:

Array
(
    [object_name_1] => Array
        (
            [db] => x
            [form] => y
            [value] => z
        )
        ...
    [object_name_4] => Array
        (
            [db] => x
            [form] => y
            [value] => z
        )
        ...
    [object_name_n] => Array
        (
            [db] => x
            [form] => y
            [value] => z
        )
        ...
    [object_name_a] => Array
        (
            [db] => x
            [form] => y
            [value] => z
        )
        ...
    [object_name_e] => Array
        (
            [db] => x
            [form] => y
            [value] => z
        )
        ...
    [object_name_z] => Array
        (
            [db] => x
            [form] => y
            [value] => z
        )
        ...
)

感谢您的时间和帮助!

2 回复 | 直到 11 年前

1

2

Fabian Schmengler 11 年前

它不是迭代器类的内置功能,但您仍然可以使用 RecursiveIteratorIterator 并建立一个堆栈,当你到达一片叶子时,你可以向后看一步。

以下是更多的PoC,它不是一个超级清洁的解决方案,但它是有效的,应该证明其原理:

实例

class MyIterator extends RecursiveIteratorIterator {
  protected $stack = array();
  protected $result = array();

  public function __construct($data)
  {
    parent::__construct(new RecursiveArrayIterator($data), RecursiveIteratorIterator::SELF_FIRST);
  }
  public function getObjects()
  {
    foreach($this as $dummy);
    return $this->result;
  }

  public function rewind()
  {
    parent::rewind();
    $this->stack = array();
    $this->result = array();
    $this->pushIfNoLeaf();
  }
  public function next()
  {
    parent::next();
    $this->pushIfNoLeaf();
  }
  public function beginIteration()
  {
    parent::beginIteration();
    $this->popIfLeaf();
  }
  public function beginChildren()
  {
    parent::beginChildren();
    $this->popIfLeaf();
  }
  protected function pushIfNoLeaf()
  {
    if ($this->getSubIterator()->hasChildren()) {
      $this->stack[] = array('key' => $this->key(), 'value' => $this->current());
    }
  }
  protected function popIfLeaf()
  {
    if (!$this->getSubIterator()->hasChildren()) {
      $item = array_pop($this->stack);
      $this->result[$item['key']] = $item['value'];
    }
  }
}
$data = array(
'obj1' => array(1,2,3),
'arr1' => array(
  'obj2' => array(4,5,6),
  'obj3' => array(7,8,9)
)
);

$iterator = new MyIterator($data);
var_dump($iterator->getObjects());

输出示例

array(3) {
  ["obj1"]=>
  array(3) {
    [0]=>
    int(1)
    [1]=>
    int(2)
    [2]=>
    int(3)
  }
  ["obj2"]=>
  array(3) {
    [0]=>
    int(4)
    [1]=>
    int(5)
    [2]=>
    int(6)
  }
  ["obj3"]=>
  array(3) {
    [0]=>
    int(7)
    [1]=>
    int(8)
    [2]=>
    int(9)
  }
}

DEMO

2

0

Michael 11 年前

使用 end 然后 prev 就像这样:

$array = array('one' => 1, 'two' => 2, 'three' => 3);

end($array);

echo prev($array); // Ouputs 2

echo key($array); // Ouputs 'two'

在你的情况下,你会:

$array = array(

  0 => array(

    0 => (object) array('name' => 'a'),

    1 => (object) array('name' => 'b'),

    2 => (object) array('name' => 'c'),

  ),

  1 => array(

    3 => (object) array('name' => 'd'),

    4 => (object) array('name' => 'e'),

    5 => (object) array('name' => 'f'),

  ),

);

$objects = array();

foreach ($array as $a)
{

  end($a);

  $prev = prev($a);

  $objects[key($a)] = $prev;

}

echo '<pre>' . print_r($objects, TRUE) . '</pre>';

输出:

Array
(
    [1] => stdClass Object
        (
            [name] => b
        )

    [4] => stdClass Object
        (
            [name] => e
        )

)