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   1  <?php
   2  /**
   3   * Zend Framework (http://framework.zend.com/)
   4   *
   5   * @link      http://github.com/zendframework/zend-eventmanager for the canonical source repository
   6   * @copyright Copyright (c) 2005-2015 Zend Technologies USA Inc. (http://www.zend.com)
   7   * @license   https://github.com/zendframework/zend-eventmanager/blob/master/LICENSE.md
   8   */
   9  
  10  namespace Zend\EventManager\Filter;
  11  
  12  use Zend\EventManager\Exception;
  13  use Zend\Stdlib\FastPriorityQueue;
  14  
  15  /**
  16   * Specialized priority queue implementation for use with an intercepting
  17   * filter chain.
  18   *
  19   * Allows removal
  20   */
  21  class FilterIterator extends FastPriorityQueue
  22  {
  23      /**
  24       * Does the queue contain a given value?
  25       *
  26       * @param  mixed $datum
  27       * @return bool
  28       */
  29      public function contains($datum)
  30      {
  31          foreach ($this as $item) {
  32              if ($item === $datum) {
  33                  return true;
  34              }
  35          }
  36          return false;
  37      }
  38  
  39      /**
  40       * Insert a value into the queue.
  41       *
  42       * Requires a callable.
  43       *
  44       * @param callable $value
  45       * @param mixed $priority
  46       * @return void
  47       * @throws Exception\InvalidArgumentException for non-callable $value.
  48       */
  49      public function insert($value, $priority)
  50      {
  51          if (! is_callable($value)) {
  52              throw new Exception\InvalidArgumentException(sprintf(
  53                  '%s can only aggregate callables; received %s',
  54                  __CLASS__,
  55                  (is_object($value) ? get_class($value) : gettype($value))
  56              ));
  57          }
  58          parent::insert($value, $priority);
  59      }
  60  
  61      /**
  62       * Remove a value from the queue
  63       *
  64       * This is an expensive operation. It must first iterate through all values,
  65       * and then re-populate itself. Use only if absolutely necessary.
  66       *
  67       * @param  mixed $datum
  68       * @return bool
  69       */
  70      public function remove($datum)
  71      {
  72          $this->setExtractFlags(self::EXTR_BOTH);
  73  
  74          // Iterate and remove any matches
  75          $removed = false;
  76          $items   = [];
  77          $this->rewind();
  78          while (! $this->isEmpty()) {
  79              $item = $this->extract();
  80              if ($item['data'] === $datum) {
  81                  $removed = true;
  82                  continue;
  83              }
  84              $items[] = $item;
  85          }
  86  
  87          // Repopulate
  88          foreach ($items as $item) {
  89              $this->insert($item['data'], $item['priority']);
  90          }
  91  
  92          $this->setExtractFlags(self::EXTR_DATA);
  93          return $removed;
  94      }
  95  
  96      /**
  97       * Iterate the next filter in the chain
  98       *
  99       * Iterates and calls the next filter in the chain.
 100       *
 101       * @param  mixed $context
 102       * @param  array $params
 103       * @param  FilterIterator $chain
 104       * @return mixed
 105       */
 106      public function next($context = null, array $params = [], $chain = null)
 107      {
 108          if (empty($context) || ($chain instanceof FilterIterator && $chain->isEmpty())) {
 109              return;
 110          }
 111  
 112          //We can't extract from an empty heap
 113          if ($this->isEmpty()) {
 114              return;
 115          }
 116  
 117          $next = $this->extract();
 118          return $next($context, $params, $chain);
 119      }
 120  }