Add $wgDiffEngine

[lhc/web/wiklou.git] / includes / diff / DifferenceEngine.php

diff --git a/includes/diff/DifferenceEngine.php b/includes/diff/DifferenceEngine.php
index 4235488..af01ca1 100644 (file)
--- a/includes/diff/DifferenceEngine.php
+++ b/includes/diff/DifferenceEngine.php
@@ -1178,7 +1178,7 @@ class DifferenceEngine extends ContextSource {
                $engine = $this->getEngine();
                $params = [
                        'diff',
-                       $engine,
+                       $engine === 'php' ? false : $engine, // Back compat
                        self::DIFF_VERSION,
                        "old-{$this->mOldid}",
                        "rev-{$this->mNewid}"
@@ -1288,32 +1288,59 @@ class DifferenceEngine extends ContextSource {
        }
 
        /**
-        * Process ExternalDiffEngine config and get a sane, usable engine
+        * Process DiffEngine config and get a sane, usable engine
         *
-        * @return bool|string 'wikidiff2', path to an executable, or false
+        * @return string 'wikidiff2', 'php', or path to an executable
         * @internal For use by this class and TextSlotDiffRenderer only.
         */
        public static function getEngine() {
+               $diffEngine = MediaWikiServices::getInstance()->getMainConfig()
+                       ->get( 'DiffEngine' );
                $externalDiffEngine = MediaWikiServices::getInstance()->getMainConfig()
                        ->get( 'ExternalDiffEngine' );
 
-               if ( $externalDiffEngine ) {
-                       if ( is_string( $externalDiffEngine ) ) {
-                               if ( is_executable( $externalDiffEngine ) ) {
-                                       return $externalDiffEngine;
-                               }
-                               wfDebug( 'ExternalDiffEngine config points to a non-executable, ignoring' );
-                       } else {
-                               wfWarn( 'ExternalDiffEngine config is set to a non-string value, ignoring' );
-                       }
-               }
+               if ( $diffEngine === null ) {
+                       $engines = [ 'external', 'wikidiff2', 'php' ];
+               } else {
+                       $engines = [ $diffEngine ];
+               }
+
+               $failureReason = null;
+               foreach ( $engines as $engine ) {
+                       switch ( $engine ) {
+                               case 'external':
+                                       if ( is_string( $externalDiffEngine ) ) {
+                                               if ( is_executable( $externalDiffEngine ) ) {
+                                                       return $externalDiffEngine;
+                                               }
+                                               $failureReason = 'ExternalDiffEngine config points to a non-executable';
+                                               if ( $diffEngine === null ) {
+                                                       wfDebug( "$failureReason, ignoring" );
+                                               }
+                                       } else {
+                                               $failureReason = 'ExternalDiffEngine config is set to a non-string value';
+                                               if ( $diffEngine === null && $externalDiffEngine ) {
+                                                       wfWarn( "$failureReason, ignoring" );
+                                               }
+                                       }
+                                       break;
 
-               if ( function_exists( 'wikidiff2_do_diff' ) ) {
-                       return 'wikidiff2';
-               }
+                               case 'wikidiff2':
+                                       if ( function_exists( 'wikidiff2_do_diff' ) ) {
+                                               return 'wikidiff2';
+                                       }
+                                       $failureReason = 'wikidiff2 is not available';
+                                       break;
 
-               // Native PHP
-               return false;
+                               case 'php':
+                                       // Always available.
+                                       return 'php';
+
+                               default:
+                                       throw new DomainException( 'Invalid value for $wgDiffEngine: ' . $engine );
+                       }
+               }
+               throw new UnexpectedValueException( "Cannot use diff engine '$engine': $failureReason" );
        }
 
        /**
@@ -1367,7 +1394,7 @@ class DifferenceEngine extends ContextSource {
                $engine = self::getEngine();
                if ( $engine === 'wikidiff2' ) {
                        return $this->debug( 'wikidiff2' );
-               } elseif ( $engine === false ) {
+               } elseif ( $engine === 'php' ) {
                        return $this->debug( 'native PHP' );
                } else {
                        return $this->debug( "external $engine" );