includes/DeferredStringifier.php

   1 <?php
   2 /**
   3  * Class that defers a slow string generation until the string is actually needed.
   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  */
  22
  23 /**
  24  * @since 1.25
  25  */
  26 class DeferredStringifier {
  27         /** @var callable Callback used for result string generation */
  28         private $callback;
  29         /** @var array */
  30         private $params;
  31         /** @var string */
  32         private $result;
  33
  34         /**
  35          * @param callable $callback Callback that gets called by __toString
  36          * @param mixed $param,... Parameters to the callback
  37          */
  38         public function __construct( $callback /*...*/ ) {
  39                 $this->params = func_get_args();
  40                 array_shift( $this->params );
  41                 $this->callback = $callback;
  42         }
  43
  44         /**
  45          * Returns a string generated by callback
  46          *
  47          * @return string
  48          */
  49         public function __toString() {
  50                 if ( $this->result === null ) {
  51                         $this->result = call_user_func_array( $this->callback, $this->params );
  52                 }
  53                 return $this->result;
  54         }
  55 }