From 9e3e3306b0224a2c5dedfa08c31b6559918171f1 Mon Sep 17 00:00:00 2001
From: Bene <benestar.wikimedia@gmail.com>
Date: Fri, 5 Feb 2016 14:40:39 +0100
Subject: [PATCH] Allow callbacks to be passed to $wgContentHandlers

Change-Id: Icf980313a6e7fcc83f5183c450b0a824353596b8
---
 RELEASE-NOTES-1.27                            |  2 ++
 docs/contenthandler.txt                       |  3 ++-
 includes/DefaultSettings.php                  |  3 ++-
 includes/content/ContentHandler.php           | 11 +++++---
 .../includes/content/ContentHandlerTest.php   | 25 +++++++++++++++++++
 5 files changed, 39 insertions(+), 5 deletions(-)

diff --git a/RELEASE-NOTES-1.27 b/RELEASE-NOTES-1.27
index 5b9b2b81e0..d1f8ca77ce 100644
--- a/RELEASE-NOTES-1.27
+++ b/RELEASE-NOTES-1.27
@@ -158,6 +158,8 @@ production.
   aria-describedby, aria-flowto, aria-label, aria-labelledby, aria-owns.
 * Removed "presentation" restriction on the HTML role attribute in wikitext.
   All values are now allowed for the role attribute.
+* $wgContentHandlers now also supports callbacks to create an instance of the
+  appropriate ContentHandler subclass.
 
 === External library changes in 1.27 ===
 
diff --git a/docs/contenthandler.txt b/docs/contenthandler.txt
index 5f9a0b039e..f1f478ef31 100644
--- a/docs/contenthandler.txt
+++ b/docs/contenthandler.txt
@@ -148,7 +148,8 @@ using a model or format different from the default will result in an error.
 
 There are some new globals that can be used to control the behavior of the ContentHandler facility:
 
-* $wgContentHandlers associates content model IDs with the names of the appropriate ContentHandler subclasses.
+* $wgContentHandlers associates content model IDs with the names of the appropriate ContentHandler subclasses
+  or callbacks that create an instance of the appropriate ContentHandler subclass.
 
 * $wgNamespaceContentModels maps namespace IDs to a content model that should be the default for that namespace.
 
diff --git a/includes/DefaultSettings.php b/includes/DefaultSettings.php
index 9c7106f83f..3ac3c8fc4e 100644
--- a/includes/DefaultSettings.php
+++ b/includes/DefaultSettings.php
@@ -904,7 +904,8 @@ $wgMediaHandlers = array(
 
 /**
  * Plugins for page content model handling.
- * Each entry in the array maps a model id to a class name.
+ * Each entry in the array maps a model id to a class name or callback
+ * that creates an instance of the appropriate ContentHandler subclass.
  *
  * @since 1.21
  */
diff --git a/includes/content/ContentHandler.php b/includes/content/ContentHandler.php
index acaa288f43..e898e720b8 100644
--- a/includes/content/ContentHandler.php
+++ b/includes/content/ContentHandler.php
@@ -357,11 +357,16 @@ abstract class ContentHandler {
 				throw new MWException( "ContentHandlerForModelID must supply a ContentHandler instance" );
 			}
 		} else {
-			$class = $wgContentHandlers[$modelId];
-			$handler = new $class( $modelId );
+			$classOrCallback = $wgContentHandlers[$modelId];
+
+			if ( is_callable( $classOrCallback ) ) {
+				$handler = call_user_func( $classOrCallback, $modelId );
+			} else {
+				$handler = new $classOrCallback( $modelId );
+			}
 
 			if ( !( $handler instanceof ContentHandler ) ) {
-				throw new MWException( "$class from \$wgContentHandlers is not " .
+				throw new MWException( "$classOrCallback from \$wgContentHandlers is not " .
 					"compatible with ContentHandler" );
 			}
 		}
diff --git a/tests/phpunit/includes/content/ContentHandlerTest.php b/tests/phpunit/includes/content/ContentHandlerTest.php
index 8178c12efa..a72247ba69 100644
--- a/tests/phpunit/includes/content/ContentHandlerTest.php
+++ b/tests/phpunit/includes/content/ContentHandlerTest.php
@@ -26,6 +26,9 @@ class ContentHandlerTest extends MediaWikiTestCase {
 				CONTENT_MODEL_CSS => 'CssContentHandler',
 				CONTENT_MODEL_TEXT => 'TextContentHandler',
 				'testing' => 'DummyContentHandlerForTesting',
+				'testing-callbacks' => function( $modelId ) {
+					return new DummyContentHandlerForTesting( $modelId );
+				}
 			),
 		) );
 
@@ -378,4 +381,26 @@ class ContentHandlerTest extends MediaWikiTestCase {
 
 		return true;
 	}
+
+	public function provideGetModelForID() {
+		return array(
+			array( CONTENT_MODEL_WIKITEXT, 'WikitextContentHandler' ),
+			array( CONTENT_MODEL_JAVASCRIPT, 'JavaScriptContentHandler' ),
+			array( CONTENT_MODEL_JSON, 'JsonContentHandler' ),
+			array( CONTENT_MODEL_CSS, 'CssContentHandler' ),
+			array( CONTENT_MODEL_TEXT, 'TextContentHandler' ),
+			array( 'testing', 'DummyContentHandlerForTesting' ),
+			array( 'testing-callbacks', 'DummyContentHandlerForTesting' ),
+		);
+	}
+
+	/**
+	 * @dataProvider provideGetModelForID
+	 */
+	public function testGetModelForID( $modelId, $handlerClass ) {
+		$handler = ContentHandler::getForModelID( $modelId );
+
+		$this->assertInstanceOf( $handlerClass, $handler );
+	}
+
 }
-- 
2.20.1