includes/diff/SlotDiffRenderer.php

   1 <?php
   2 /**
   3  * Renders a diff for a single slot.
   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  * @ingroup DifferenceEngine
  22  */
  23 use Wikimedia\Assert\Assert;
  24
  25 /**
  26  * Renders a diff for a single slot (that is, a diff between two content objects).
  27  *
  28  * Callers should obtain this class by invoking ContentHandler::getSlotDiffRendererClass
  29  * on the content handler of the new content object (ie. the one shown on the right side
  30  * of the diff), or of the old one if the new one does not exist.
  31  *
  32  * The default implementation just does a text diff on the native text representation.
  33  * Content handler extensions can subclass this to provide a more appropriate diff method by
  34  * overriding ContentHandler::getSlotDiffRendererClass. Other extensions that want to interfere
  35  * with diff generation in some way can use the GetSlotDiffRenderer hook.
  36  *
  37  * @ingroup DifferenceEngine
  38  */
  39 abstract class SlotDiffRenderer {
  40
  41         /**
  42          * Get a diff between two content objects. One of them might be null (meaning a slot was
  43          * created or removed), but both cannot be. $newContent (or if it's null then $oldContent)
  44          * must have the same content model that was used to obtain this diff renderer.
  45          * @param Content|null $oldContent
  46          * @param Content|null $newContent
  47          * @return string
  48          */
  49         abstract public function getDiff( Content $oldContent = null, Content $newContent = null );
  50
  51         /**
  52          * Add modules needed for correct styling/behavior of the diff.
  53          * @param OutputPage $output
  54          */
  55         public function addModules( OutputPage $output ) {
  56         }
  57
  58         /**
  59          * Return any extra keys to split the diff cache by.
  60          * @return array
  61          */
  62         public function getExtraCacheKeys() {
  63                 return [];
  64         }
  65
  66         /**
  67          * Helper method to normalize the input of getDiff().
  68          * Verifies that at least one of $oldContent and $newContent is not null, verifies that
  69          * they are instances of one of the allowed classes (if provided), and replaces null with
  70          * empty content.
  71          * @param Content|null &$oldContent
  72          * @param Content|null &$newContent
  73          * @param string|array|null $allowedClasses
  74          */
  75         protected function normalizeContents(
  76                 Content &$oldContent = null, Content &$newContent = null, $allowedClasses = null
  77         ) {
  78                 if ( !$oldContent && !$newContent ) {
  79                         throw new InvalidArgumentException( '$oldContent and $newContent cannot both be null' );
  80                 }
  81
  82                 if ( $allowedClasses ) {
  83                         if ( is_array( $allowedClasses ) ) {
  84                                 $allowedClasses = implode( '|', $allowedClasses );
  85                         }
  86                         Assert::parameterType( $allowedClasses . '|null', $oldContent, '$oldContent' );
  87                         Assert::parameterType( $allowedClasses . '|null', $newContent, '$newContent' );
  88                 }
  89
  90                 if ( !$oldContent ) {
  91                         $oldContent = $newContent->getContentHandler()->makeEmptyContent();
  92                 } elseif ( !$newContent ) {
  93                         $newContent = $oldContent->getContentHandler()->makeEmptyContent();
  94                 }
  95         }
  96
  97 }