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   1  <?php
   2  /**
   3   * Convenience class for generating iterators from iterators.
   4   *
   5   * This program is free software; you can redistribute it and/or modify
   6   * it under the terms of the GNU General Public License as published by
   7   * the Free Software Foundation; either version 2 of the License, or
   8   * (at your option) any later version.
   9   *
  10   * This program is distributed in the hope that it will be useful,
  11   * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13   * GNU General Public License for more details.
  14   *
  15   * You should have received a copy of the GNU General Public License along
  16   * with this program; if not, write to the Free Software Foundation, Inc.,
  17   * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18   * http://www.gnu.org/copyleft/gpl.html
  19   *
  20   * @file
  21   * @author Aaron Schulz
  22   */
  23  
  24  /**
  25   * Convenience class for generating iterators from iterators.
  26   *
  27   * @since 1.21
  28   */
  29  class MappedIterator extends FilterIterator {
  30      /** @var callable */
  31      protected $vCallback;
  32      /** @var callable */
  33      protected $aCallback;
  34      /** @var array */
  35      protected $cache = array();
  36  
  37      protected $rewound = false; // boolean; whether rewind() has been called
  38  
  39      /**
  40       * Build an new iterator from a base iterator by having the former wrap the
  41       * later, returning the result of "value" callback for each current() invocation.
  42       * The callback takes the result of current() on the base iterator as an argument.
  43       * The keys of the base iterator are reused verbatim.
  44       *
  45       * An "accept" callback can also be provided which will be called for each value in
  46       * the base iterator (post-callback) and will return true if that value should be
  47       * included in iteration of the MappedIterator (otherwise it will be filtered out).
  48       *
  49       * @param Iterator|Array $iter
  50       * @param callable $vCallback Value transformation callback
  51       * @param array $options Options map (includes "accept") (since 1.22)
  52       * @throws UnexpectedValueException
  53       */
  54  	public function __construct( $iter, $vCallback, array $options = array() ) {
  55          if ( is_array( $iter ) ) {
  56              $baseIterator = new ArrayIterator( $iter );
  57          } elseif ( $iter instanceof Iterator ) {
  58              $baseIterator = $iter;
  59          } else {
  60              throw new UnexpectedValueException( "Invalid base iterator provided." );
  61          }
  62          parent::__construct( $baseIterator );
  63          $this->vCallback = $vCallback;
  64          $this->aCallback = isset( $options['accept'] ) ? $options['accept'] : null;
  65      }
  66  
  67  	public function next() {
  68          $this->cache = array();
  69          parent::next();
  70      }
  71  
  72  	public function rewind() {
  73          $this->rewound = true;
  74          $this->cache = array();
  75          parent::rewind();
  76      }
  77  
  78  	public function accept() {
  79          $value = call_user_func( $this->vCallback, $this->getInnerIterator()->current() );
  80          $ok = ( $this->aCallback ) ? call_user_func( $this->aCallback, $value ) : true;
  81          if ( $ok ) {
  82              $this->cache['current'] = $value;
  83          }
  84  
  85          return $ok;
  86      }
  87  
  88  	public function key() {
  89          $this->init();
  90  
  91          return parent::key();
  92      }
  93  
  94  	public function valid() {
  95          $this->init();
  96  
  97          return parent::valid();
  98      }
  99  
 100  	public function current() {
 101          $this->init();
 102          if ( parent::valid() ) {
 103              return $this->cache['current'];
 104          } else {
 105              return null; // out of range
 106          }
 107      }
 108  
 109      /**
 110       * Obviate the usual need for rewind() before using a FilterIterator in a manual loop
 111       */
 112  	protected function init() {
 113          if ( !$this->rewound ) {
 114              $this->rewind();
 115          }
 116      }
 117  }