Update to MediaWiki 1.24.1

15 files changed, 987 insertions, 542 deletions

diff --git a/includes/content/AbstractContent.php b/includes/content/AbstractContent.php
index 137efb8a..9d257a6a 100644
--- a/includes/content/AbstractContent.php
+++ b/includes/content/AbstractContent.php
@@ -32,7 +32,6 @@
  * @ingroup Content
  */
 abstract class AbstractContent implements Content {
-
 	/**
 	 * Name of the content model this Content object represents.
 	 * Use with CONTENT_MODEL_XXX constants
@@ -44,7 +43,7 @@ abstract class AbstractContent implements Content {
 	protected $model_id;
 
 	/**
-	 * @param string|null $modelId
+	 * @param string $modelId
 	 *
 	 * @since 1.21
 	 */
@@ -53,23 +52,21 @@ abstract class AbstractContent implements Content {
 	}
 
 	/**
-	 * @see Content::getModel
-	 *
 	 * @since 1.21
+	 *
+	 * @see Content::getModel
 	 */
 	public function getModel() {
 		return $this->model_id;
 	}
 
 	/**
-	 * Throws an MWException if $model_id is not the id of the content model
-	 * supported by this Content object.
-	 *
 	 * @since 1.21
 	 *
 	 * @param string $modelId The model to check
 	 *
-	 * @throws MWException
+	 * @throws MWException If the provided ID is not the ID of the content model supported by this
+	 * Content object.
 	 */
 	protected function checkModelID( $modelId ) {
 		if ( $modelId !== $this->model_id ) {
@@ -82,40 +79,40 @@ abstract class AbstractContent implements Content {
 	}
 
 	/**
-	 * @see Content::getContentHandler
-	 *
 	 * @since 1.21
+	 *
+	 * @see Content::getContentHandler
 	 */
 	public function getContentHandler() {
 		return ContentHandler::getForContent( $this );
 	}
 
 	/**
-	 * @see Content::getDefaultFormat
-	 *
 	 * @since 1.21
+	 *
+	 * @see Content::getDefaultFormat
 	 */
 	public function getDefaultFormat() {
 		return $this->getContentHandler()->getDefaultFormat();
 	}
 
 	/**
-	 * @see Content::getSupportedFormats
-	 *
 	 * @since 1.21
+	 *
+	 * @see Content::getSupportedFormats
 	 */
 	public function getSupportedFormats() {
 		return $this->getContentHandler()->getSupportedFormats();
 	}
 
 	/**
-	 * @see Content::isSupportedFormat
+	 * @since 1.21
 	 *
 	 * @param string $format
 	 *
-	 * @since 1.21
+	 * @return bool
 	 *
-	 * @return boolean
+	 * @see Content::isSupportedFormat
 	 */
 	public function isSupportedFormat( $format ) {
 		if ( !$format ) {
@@ -126,13 +123,11 @@ abstract class AbstractContent implements Content {
 	}
 
 	/**
-	 * Throws an MWException if $this->isSupportedFormat( $format ) does not
-	 * return true.
-	 *
 	 * @since 1.21
 	 *
-	 * @param string $format
-	 * @throws MWException
+	 * @param string $format The serialization format to check.
+	 *
+	 * @throws MWException If the format is not supported by this content handler.
 	 */
 	protected function checkFormat( $format ) {
 		if ( !$this->isSupportedFormat( $format ) ) {
@@ -144,48 +139,50 @@ abstract class AbstractContent implements Content {
 	}
 
 	/**
-	 * @see Content::serialize
-	 *
-	 * @param string|null $format
-	 *
 	 * @since 1.21
 	 *
+	 * @param string $format
+	 *
 	 * @return string
+	 *
+	 * @see Content::serialize
 	 */
 	public function serialize( $format = null ) {
 		return $this->getContentHandler()->serializeContent( $this, $format );
 	}
 
 	/**
-	 * @see Content::isEmpty
-	 *
 	 * @since 1.21
 	 *
-	 * @return boolean
+	 * @return bool
+	 *
+	 * @see Content::isEmpty
 	 */
 	public function isEmpty() {
 		return $this->getSize() === 0;
 	}
 
 	/**
-	 * @see Content::isValid
+	 * Subclasses may override this to implement (light weight) validation.
 	 *
 	 * @since 1.21
 	 *
-	 * @return boolean
+	 * @return bool Always true.
+	 *
+	 * @see Content::isValid
 	 */
 	public function isValid() {
 		return true;
 	}
 
 	/**
-	 * @see Content::equals
-	 *
 	 * @since 1.21
 	 *
-	 * @param Content|null $that
+	 * @param Content $that
+	 *
+	 * @return bool
 	 *
-	 * @return boolean
+	 * @see Content::equals
 	 */
 	public function equals( Content $that = null ) {
 		if ( is_null( $that ) ) {
@@ -215,26 +212,19 @@ abstract class AbstractContent implements Content {
 	 * Subclasses may override this to determine the secondary data updates more
 	 * efficiently, preferably without the need to generate a parser output object.
 	 *
-	 * @see Content::getSecondaryDataUpdates()
+	 * @since 1.21
 	 *
-	 * @param $title Title The context for determining the necessary updates
-	 * @param $old Content|null An optional Content object representing the
-	 *    previous content, i.e. the content being replaced by this Content
-	 *    object.
-	 * @param $recursive boolean Whether to include recursive updates (default:
-	 *    false).
-	 * @param $parserOutput ParserOutput|null Optional ParserOutput object.
-	 *    Provide if you have one handy, to avoid re-parsing of the content.
+	 * @param Title $title
+	 * @param Content $old
+	 * @param bool $recursive
+	 * @param ParserOutput $parserOutput
 	 *
-	 * @return Array. A list of DataUpdate objects for putting information
-	 *    about this content object somewhere.
+	 * @return DataUpdate[]
 	 *
-	 * @since 1.21
+	 * @see Content::getSecondaryDataUpdates()
 	 */
-	public function getSecondaryDataUpdates( Title $title,
-		Content $old = null,
-		$recursive = true, ParserOutput $parserOutput = null
-	) {
+	public function getSecondaryDataUpdates( Title $title, Content $old = null,
+		$recursive = true, ParserOutput $parserOutput = null ) {
 		if ( $parserOutput === null ) {
 			$parserOutput = $this->getParserOutput( $title, null, null, false );
 		}
@@ -243,9 +233,11 @@ abstract class AbstractContent implements Content {
 	}
 
 	/**
-	 * @see Content::getRedirectChain
-	 *
 	 * @since 1.21
+	 *
+	 * @return Title[]|null
+	 *
+	 * @see Content::getRedirectChain
 	 */
 	public function getRedirectChain() {
 		global $wgMaxRedirects;
@@ -264,7 +256,7 @@ abstract class AbstractContent implements Content {
 				break;
 			}
 			// Redirects to some special pages are not permitted
-			if ( $newtitle instanceOf Title && $newtitle->isValidRedirectTarget() ) {
+			if ( $newtitle instanceof Title && $newtitle->isValidRedirectTarget() ) {
 				// The new title passes the checks, so make that our current
 				// title so that further recursion can be checked
 				$title = $newtitle;
@@ -273,104 +265,126 @@ abstract class AbstractContent implements Content {
 				break;
 			}
 		}
+
 		return $titles;
 	}
 
 	/**
-	 * @see Content::getRedirectTarget
+	 * Subclasses that implement redirects should override this.
 	 *
 	 * @since 1.21
+	 *
+	 * @return null
+	 *
+	 * @see Content::getRedirectTarget
 	 */
 	public function getRedirectTarget() {
 		return null;
 	}
 
 	/**
-	 * @see Content::getUltimateRedirectTarget
-	 * @note: migrated here from Title::newFromRedirectRecurse
+	 * @note Migrated here from Title::newFromRedirectRecurse.
 	 *
 	 * @since 1.21
+	 *
+	 * @return Title|null
+	 *
+	 * @see Content::getUltimateRedirectTarget
 	 */
 	public function getUltimateRedirectTarget() {
 		$titles = $this->getRedirectChain();
+
 		return $titles ? array_pop( $titles ) : null;
 	}
 
 	/**
-	 * @see Content::isRedirect
-	 *
 	 * @since 1.21
 	 *
 	 * @return bool
+	 *
+	 * @see Content::isRedirect
 	 */
 	public function isRedirect() {
 		return $this->getRedirectTarget() !== null;
 	}
 
 	/**
-	 * @see Content::updateRedirect
-	 *
 	 * This default implementation always returns $this.
-	 *
-	 * @param Title $target
+	 * Subclasses that implement redirects should override this.
 	 *
 	 * @since 1.21
 	 *
+	 * @param Title $target
+	 *
 	 * @return Content $this
+	 *
+	 * @see Content::updateRedirect
 	 */
 	public function updateRedirect( Title $target ) {
 		return $this;
 	}
 
 	/**
-	 * @see Content::getSection
-	 *
 	 * @since 1.21
+	 *
+	 * @return null
+	 *
+	 * @see Content::getSection
 	 */
 	public function getSection( $sectionId ) {
 		return null;
 	}
 
 	/**
-	 * @see Content::replaceSection
-	 *
 	 * @since 1.21
+	 *
+	 * @return null
+	 *
+	 * @see Content::replaceSection
 	 */
-	public function replaceSection( $section, Content $with, $sectionTitle = '' ) {
+	public function replaceSection( $sectionId, Content $with, $sectionTitle = '' ) {
 		return null;
 	}
 
 	/**
-	 * @see Content::preSaveTransform
-	 *
 	 * @since 1.21
+	 *
+	 * @return Content $this
+	 *
+	 * @see Content::preSaveTransform
 	 */
 	public function preSaveTransform( Title $title, User $user, ParserOptions $popts ) {
 		return $this;
 	}
 
 	/**
-	 * @see Content::addSectionHeader
-	 *
 	 * @since 1.21
+	 *
+	 * @return Content $this
+	 *
+	 * @see Content::addSectionHeader
 	 */
 	public function addSectionHeader( $header ) {
 		return $this;
 	}
 
 	/**
-	 * @see Content::preloadTransform
-	 *
 	 * @since 1.21
+	 *
+	 * @return Content $this
+	 *
+	 * @see Content::preloadTransform
 	 */
-	public function preloadTransform( Title $title, ParserOptions $popts ) {
+	public function preloadTransform( Title $title, ParserOptions $popts, $params = array() ) {
 		return $this;
 	}
 
 	/**
-	 * @see Content::prepareSave
-	 *
 	 * @since 1.21
+	 *
+	 * @return Status
+	 *
+	 * @see Content::prepareSave
 	 */
 	public function prepareSave( WikiPage $page, $flags, $baseRevId, User $user ) {
 		if ( $this->isValid() ) {
@@ -381,53 +395,47 @@ abstract class AbstractContent implements Content {
 	}
 
 	/**
-	 * @see Content::getDeletionUpdates
-	 *
 	 * @since 1.21
 	 *
-	 * @param $page WikiPage the deleted page
-	 * @param $parserOutput null|ParserOutput optional parser output object
-	 *    for efficient access to meta-information about the content object.
-	 *    Provide if you have one handy.
+	 * @param WikiPage $page
+	 * @param ParserOutput $parserOutput
+	 *
+	 * @return LinksDeletionUpdate[]
 	 *
-	 * @return array A list of DataUpdate instances that will clean up the
-	 *    database after deletion.
+	 * @see Content::getDeletionUpdates
 	 */
-	public function getDeletionUpdates( WikiPage $page,
-		ParserOutput $parserOutput = null )
-	{
+	public function getDeletionUpdates( WikiPage $page, ParserOutput $parserOutput = null ) {
 		return array(
 			new LinksDeletionUpdate( $page ),
 		);
 	}
 
 	/**
-	 * This default implementation always returns false. Subclasses may override this to supply matching logic.
-	 *
-	 * @see Content::matchMagicWord
+	 * This default implementation always returns false. Subclasses may override
+	 * this to supply matching logic.
 	 *
 	 * @since 1.21
 	 *
 	 * @param MagicWord $word
 	 *
-	 * @return bool
+	 * @return bool Always false.
+	 *
+	 * @see Content::matchMagicWord
 	 */
 	public function matchMagicWord( MagicWord $word ) {
 		return false;
 	}
 
 	/**
-	 * @see Content::convert()
-	 *
 	 * This base implementation calls the hook ConvertContent to enable custom conversions.
 	 * Subclasses may override this to implement conversion for "their" content model.
 	 *
-	 * @param string  $toModel the desired content model, use the CONTENT_MODEL_XXX flags.
-	 * @param string  $lossy flag, set to "lossy" to allow lossy conversion. If lossy conversion is
-	 * not allowed, full round-trip conversion is expected to work without losing information.
+	 * @param string $toModel
+	 * @param string $lossy
 	 *
-	 * @return Content|bool A content object with the content model $toModel, or false if
-	 * that conversion is not supported.
+	 * @return Content|bool
+	 *
+	 * @see Content::convert()
 	 */
 	public function convert( $toModel, $lossy = '' ) {
 		if ( $this->getModel() === $toModel ) {
@@ -439,6 +447,77 @@ abstract class AbstractContent implements Content {
 		$result = false;
 
 		wfRunHooks( 'ConvertContent', array( $this, $toModel, $lossy, &$result ) );
+
 		return $result;
 	}
+
+	/**
+	 * Returns a ParserOutput object containing information derived from this content.
+	 * Most importantly, unless $generateHtml was false, the return value contains an
+	 * HTML representation of the content.
+	 *
+	 * Subclasses that want to control the parser output may override this, but it is
+	 * preferred to override fillParserOutput() instead.
+	 *
+	 * Subclasses that override getParserOutput() itself should take care to call the
+	 * ContentGetParserOutput hook.
+	 *
+	 * @since 1.24
+	 *
+	 * @param Title $title Context title for parsing
+	 * @param int|null $revId Revision ID (for {{REVISIONID}})
+	 * @param ParserOptions|null $options Parser options
+	 * @param bool $generateHtml Whether or not to generate HTML
+	 *
+	 * @return ParserOutput Containing information derived from this content.
+	 */
+	public function getParserOutput( Title $title, $revId = null,
+		ParserOptions $options = null, $generateHtml = true
+	) {
+		if ( $options === null ) {
+			$options = $this->getContentHandler()->makeParserOptions( 'canonical' );
+		}
+
+		$po = new ParserOutput();
+
+		if ( wfRunHooks( 'ContentGetParserOutput',
+			array( $this, $title, $revId, $options, $generateHtml, &$po ) ) ) {
+
+			// Save and restore the old value, just in case something is reusing
+			// the ParserOptions object in some weird way.
+			$oldRedir = $options->getRedirectTarget();
+			$options->setRedirectTarget( $this->getRedirectTarget() );
+			$this->fillParserOutput( $title, $revId, $options, $generateHtml, $po );
+			$options->setRedirectTarget( $oldRedir );
+		}
+
+		return $po;
+	}
+
+	/**
+	 * Fills the provided ParserOutput with information derived from the content.
+	 * Unless $generateHtml was false, this includes an HTML representation of the content.
+	 *
+	 * This is called by getParserOutput() after consulting the ContentGetParserOutput hook.
+	 * Subclasses are expected to override this method (or getParserOutput(), if need be).
+	 * Subclasses of TextContent should generally override getHtml() instead.
+	 *
+	 * This placeholder implementation always throws an exception.
+	 *
+	 * @since 1.24
+	 *
+	 * @param Title $title Context title for parsing
+	 * @param int|null $revId Revision ID (for {{REVISIONID}})
+	 * @param ParserOptions $options Parser options
+	 * @param bool $generateHtml Whether or not to generate HTML
+	 * @param ParserOutput &$output The output object to fill (reference).
+	 *
+	 * @throws MWException
+	 */
+	protected function fillParserOutput( Title $title, $revId,
+		ParserOptions $options, $generateHtml, ParserOutput &$output
+	) {
+		// Don't make abstract, so subclasses that override getParserOutput() directly don't fail.
+		throw new MWException( 'Subclasses of AbstractContent must override fillParserOutput!' );
+	}
 }
diff --git a/includes/content/CodeContentHandler.php b/includes/content/CodeContentHandler.php
new file mode 100644
index 00000000..447a2a73
--- /dev/null
+++ b/includes/content/CodeContentHandler.php
@@ -0,0 +1,65 @@
+<?php
+/**
+ * Content handler for the pages with code, such as CSS, JavaScript, JSON.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ * @ingroup Content
+ */
+
+/**
+ * Content handler for code content such as CSS, JavaScript, JSON, etc
+ * @since 1.24
+ * @ingroup Content
+ */
+abstract class CodeContentHandler extends TextContentHandler {
+
+	/**
+	 * Returns the english language, because code is english, and should be handled as such.
+	 *
+	 * @param Title $title
+	 * @param Content $content
+	 *
+	 * @return Language Return of wfGetLangObj( 'en' )
+	 *
+	 * @see ContentHandler::getPageLanguage()
+	 */
+	public function getPageLanguage( Title $title, Content $content = null ) {
+		return wfGetLangObj( 'en' );
+	}
+
+	/**
+	 * Returns the english language, because code is english, and should be handled as such.
+	 *
+	 * @param Title $title
+	 * @param Content $content
+	 *
+	 * @return Language Return of wfGetLangObj( 'en' )
+	 *
+	 * @see ContentHandler::getPageViewLanguage()
+	 */
+	public function getPageViewLanguage( Title $title, Content $content = null ) {
+		return wfGetLangObj( 'en' );
+	}
+
+	/**
+	 * @return string
+	 */
+	protected function getContentClass() {
+		throw new MWException( 'Subclass must override' );
+	}
+}
diff --git a/includes/content/Content.php b/includes/content/Content.php
index 5a90e092..61b9254f 100644
--- a/includes/content/Content.php
+++ b/includes/content/Content.php
@@ -48,7 +48,7 @@ interface Content {
 	/**
 	 * @since 1.21
 	 *
-	 * @return string|false The wikitext to include when another page includes this
+	 * @return string|bool The wikitext to include when another page includes this
 	 * content, or false if the content is not includable in a wikitext page.
 	 *
 	 * @todo Allow native handling, bypassing wikitext representation, like
@@ -65,8 +65,9 @@ interface Content {
 	 *
 	 * @since 1.21
 	 *
-	 * @param int $maxLength Maximum length of the summary text
-	 * @return string The summary text
+	 * @param int $maxLength Maximum length of the summary text.
+	 *
+	 * @return string The summary text.
 	 */
 	public function getTextForSummary( $maxLength = 250 );
 
@@ -85,7 +86,7 @@ interface Content {
 	public function getNativeData();
 
 	/**
-	 * Returns the content's nominal size in bogo-bytes.
+	 * Returns the content's nominal size in "bogo-bytes".
 	 *
 	 * @return int
 	 */
@@ -97,7 +98,7 @@ interface Content {
 	 *
 	 * @since 1.21
 	 *
-	 * @return String The model id
+	 * @return string The model id
 	 */
 	public function getModel();
 
@@ -121,7 +122,7 @@ interface Content {
 	 *
 	 * @since 1.21
 	 *
-	 * @return String
+	 * @return string
 	 */
 	public function getDefaultFormat();
 
@@ -133,7 +134,7 @@ interface Content {
 	 *
 	 * @since 1.21
 	 *
-	 * @return Array of supported serialization formats
+	 * @return string[] List of supported serialization formats
 	 */
 	public function getSupportedFormats();
 
@@ -148,7 +149,8 @@ interface Content {
 	 *
 	 * @since 1.21
 	 *
-	 * @param string $format The format to check
+	 * @param string $format The serialization format to check.
+	 *
 	 * @return bool Whether the format is supported
 	 */
 	public function isSupportedFormat( $format );
@@ -160,9 +162,9 @@ interface Content {
 	 *
 	 * @since 1.21
 	 *
-	 * @param $format null|string The desired serialization format (or null for
-	 *    the default format).
-	 * @return string Serialized form of this Content object
+	 * @param string $format The desired serialization format, or null for the default format.
+	 *
+	 * @return string Serialized form of this Content object.
 	 */
 	public function serialize( $format = null );
 
@@ -185,7 +187,7 @@ interface Content {
 	 *
 	 * @since 1.21
 	 *
-	 * @return boolean
+	 * @return bool
 	 */
 	public function isValid();
 
@@ -208,7 +210,8 @@ interface Content {
 	 *
 	 * @since 1.21
 	 *
-	 * @param $that Content The Content object to compare to
+	 * @param Content $that The Content object to compare to.
+	 *
 	 * @return bool True if this Content object is equal to $that, false otherwise.
 	 */
 	public function equals( Content $that = null );
@@ -229,7 +232,7 @@ interface Content {
 	 *
 	 * @since 1.21
 	 *
-	 * @return Content. A copy of this object
+	 * @return Content A copy of this object
 	 */
 	public function copy();
 
@@ -243,7 +246,8 @@ interface Content {
 	 * @param bool $hasLinks If it is known whether this content contains
 	 *    links, provide this information here, to avoid redundant parsing to
 	 *    find out.
-	 * @return boolean
+	 *
+	 * @return bool
 	 */
 	public function isCountable( $hasLinks = null );
 
@@ -253,10 +257,14 @@ interface Content {
 	 * is needed, $generateHtml can be set to false; in that case,
 	 * $result->getText() may return null.
 	 *
-	 * @param $title Title The page title to use as a context for rendering
-	 * @param $revId null|int The revision being rendered (optional)
-	 * @param $options null|ParserOptions Any parser options
-	 * @param $generateHtml Boolean Whether to generate HTML (default: true). If false,
+	 * @note To control which options are used in the cache key for the
+	 *       generated parser output, implementations of this method
+	 *       may call ParserOutput::recordOption() on the output object.
+	 *
+	 * @param Title $title The page title to use as a context for rendering.
+	 * @param int $revId Optional revision ID being rendered.
+	 * @param ParserOptions $options Any parser options.
+	 * @param bool $generateHtml Whether to generate HTML (default: true). If false,
 	 *        the result of calling getText() on the ParserOutput object returned by
 	 *        this method is undefined.
 	 *
@@ -264,9 +272,9 @@ interface Content {
 	 *
 	 * @return ParserOutput
 	 */
-	public function getParserOutput( Title $title,
-		$revId = null,
+	public function getParserOutput( Title $title, $revId = null,
 		ParserOptions $options = null, $generateHtml = true );
+
 	// TODO: make RenderOutput and RenderOptions base classes
 
 	/**
@@ -284,24 +292,22 @@ interface Content {
 	 * Subclasses may implement this to determine the necessary updates more
 	 * efficiently, or make use of information about the old content.
 	 *
-	 * @param $title Title The context for determining the necessary updates
-	 * @param $old Content|null An optional Content object representing the
+	 * @param Title $title The context for determining the necessary updates
+	 * @param Content $old An optional Content object representing the
 	 *    previous content, i.e. the content being replaced by this Content
 	 *    object.
-	 * @param $recursive boolean Whether to include recursive updates (default:
+	 * @param bool $recursive Whether to include recursive updates (default:
 	 *    false).
-	 * @param $parserOutput ParserOutput|null Optional ParserOutput object.
+	 * @param ParserOutput $parserOutput Optional ParserOutput object.
 	 *    Provide if you have one handy, to avoid re-parsing of the content.
 	 *
-	 * @return Array. A list of DataUpdate objects for putting information
+	 * @return DataUpdate[] A list of DataUpdate objects for putting information
 	 *    about this content object somewhere.
 	 *
 	 * @since 1.21
 	 */
-	public function getSecondaryDataUpdates( Title $title,
-		Content $old = null,
-		$recursive = true, ParserOutput $parserOutput = null
-	);
+	public function getSecondaryDataUpdates( Title $title, Content $old = null,
+		$recursive = true, ParserOutput $parserOutput = null );
 
 	/**
 	 * Construct the redirect destination from this content and return an
@@ -311,7 +317,7 @@ interface Content {
 	 *
 	 * @since 1.21
 	 *
-	 * @return Array of Titles, with the destination last
+	 * @return Title[]|null List of Titles, with the destination last.
 	 */
 	public function getRedirectChain();
 
@@ -323,7 +329,7 @@ interface Content {
 	 *
 	 * @since 1.21
 	 *
-	 * @return Title: The corresponding Title
+	 * @return Title|null The corresponding Title.
 	 */
 	public function getRedirectTarget();
 
@@ -340,7 +346,7 @@ interface Content {
 	 *
 	 * @since 1.21
 	 *
-	 * @return Title
+	 * @return Title|null
 	 */
 	public function getUltimateRedirectTarget();
 
@@ -360,9 +366,10 @@ interface Content {
 	 *
 	 * @since 1.21
 	 *
-	 * @param Title $target the new redirect target
+	 * @param Title $target The new redirect target
 	 *
-	 * @return Content a new Content object with the updated redirect (or $this if this Content object isn't a redirect)
+	 * @return Content A new Content object with the updated redirect (or $this
+	 *   if this Content object isn't a redirect)
 	 */
 	public function updateRedirect( Title $target );
 
@@ -371,11 +378,11 @@ interface Content {
 	 *
 	 * @since 1.21
 	 *
-	 * @param string $sectionId The section's ID, given as a numeric string.
-	 *    The ID "0" retrieves the section before the first heading, "1" the
-	 *    text between the first heading (included) and the second heading
-	 *    (excluded), etc.
-	 * @return Content|Boolean|null The section, or false if no such section
+	 * @param string|number $sectionId Section identifier as a number or string
+	 * (e.g. 0, 1 or 'T-1'). The ID "0" retrieves the section before the first heading, "1" the
+	 * text between the first heading (included) and the second heading (excluded), etc.
+	 *
+	 * @return Content|bool|null The section, or false if no such section
 	 *    exist, or null if sections are not supported.
 	 */
 	public function getSection( $sectionId );
@@ -386,12 +393,15 @@ interface Content {
 	 *
 	 * @since 1.21
 	 *
-	 * @param $section null/false or a section number (0, 1, 2, T1, T2...), or "new"
-	 * @param $with Content: new content of the section
-	 * @param string $sectionTitle new section's subject, only if $section is 'new'
-	 * @return string Complete article text, or null if error
+	 * @param string|number|null|bool $sectionId Section identifier as a number or string
+	 * (e.g. 0, 1 or 'T-1'), null/false or an empty string for the whole page
+	 * or 'new' for a new section.
+	 * @param Content $with New content of the section
+	 * @param string $sectionTitle New section's subject, only if $section is 'new'
+	 *
+	 * @return string|null Complete article text, or null if error
 	 */
-	public function replaceSection( $section, Content $with, $sectionTitle = '' );
+	public function replaceSection( $sectionId, Content $with, $sectionTitle = '' );
 
 	/**
 	 * Returns a Content object with pre-save transformations applied (or this
@@ -399,9 +409,10 @@ interface Content {
 	 *
 	 * @since 1.21
 	 *
-	 * @param $title Title
-	 * @param $user User
-	 * @param $parserOptions null|ParserOptions
+	 * @param Title $title
+	 * @param User $user
+	 * @param ParserOptions $parserOptions
+	 *
 	 * @return Content
 	 */
 	public function preSaveTransform( Title $title, User $user, ParserOptions $parserOptions );
@@ -413,7 +424,8 @@ interface Content {
 	 *
 	 * @since 1.21
 	 *
-	 * @param $header string
+	 * @param string $header
+	 *
 	 * @return Content
 	 */
 	public function addSectionHeader( $header );
@@ -424,11 +436,13 @@ interface Content {
 	 *
 	 * @since 1.21
 	 *
-	 * @param $title Title
-	 * @param $parserOptions null|ParserOptions
+	 * @param Title $title
+	 * @param ParserOptions $parserOptions
+	 * @param array $params
+	 *
 	 * @return Content
 	 */
-	public function preloadTransform( Title $title, ParserOptions $parserOptions );
+	public function preloadTransform( Title $title, ParserOptions $parserOptions, $params = array() );
 
 	/**
 	 * Prepare Content for saving. Called before Content is saved by WikiPage::doEditContent() and in
@@ -437,24 +451,24 @@ interface Content {
 	 * This may be used to check the content's consistency with global state. This function should
 	 * NOT write any information to the database.
 	 *
-	 * Note that this method will usually be called inside the same transaction bracket that will be used
-	 * to save the new revision.
+	 * Note that this method will usually be called inside the same transaction
+	 * bracket that will be used to save the new revision.
 	 *
-	 * Note that this method is called before any update to the page table is performed. This means that
-	 * $page may not yet know a page ID.
+	 * Note that this method is called before any update to the page table is
+	 * performed. This means that $page may not yet know a page ID.
 	 *
 	 * @since 1.21
 	 *
 	 * @param WikiPage $page The page to be saved.
-	 * @param int      $flags bitfield for use with EDIT_XXX constants, see WikiPage::doEditContent()
-	 * @param int      $baseRevId the ID of the current revision
-	 * @param User     $user
+	 * @param int $flags Bitfield for use with EDIT_XXX constants, see WikiPage::doEditContent()
+	 * @param int $baseRevId The ID of the current revision
+	 * @param User $user
 	 *
-	 * @return Status A status object indicating whether the content was successfully prepared for saving.
-	 *                If the returned status indicates an error, a rollback will be performed and the
-	 *                transaction aborted.
+	 * @return Status A status object indicating whether the content was
+	 *   successfully prepared for saving. If the returned status indicates
+	 *   an error, a rollback will be performed and the transaction aborted.
 	 *
-	 * @see see WikiPage::doEditContent()
+	 * @see WikiPage::doEditContent()
 	 */
 	public function prepareSave( WikiPage $page, $flags, $baseRevId, User $user );
 
@@ -465,12 +479,12 @@ interface Content {
 	 *
 	 * @since 1.21
 	 *
-	 * @param $page WikiPage the deleted page
-	 * @param $parserOutput null|ParserOutput optional parser output object
+	 * @param WikiPage $page The deleted page
+	 * @param ParserOutput $parserOutput Optional parser output object
 	 *    for efficient access to meta-information about the content object.
 	 *    Provide if you have one handy.
 	 *
-	 * @return array A list of DataUpdate instances that will clean up the
+	 * @return DataUpdate[] A list of DataUpdate instances that will clean up the
 	 *    database after deletion.
 	 */
 	public function getDeletionUpdates( WikiPage $page,
@@ -481,9 +495,9 @@ interface Content {
 	 *
 	 * @since 1.21
 	 *
-	 * @param MagicWord $word the magic word to match
+	 * @param MagicWord $word The magic word to match
 	 *
-	 * @return bool whether this Content object matches the given magic word.
+	 * @return bool Whether this Content object matches the given magic word.
 	 */
 	public function matchMagicWord( MagicWord $word );
 
@@ -491,18 +505,19 @@ interface Content {
 	 * Converts this content object into another content object with the given content model,
 	 * if that is possible.
 	 *
-	 * @param string  $toModel the desired content model, use the CONTENT_MODEL_XXX flags.
-	 * @param string  $lossy flag, set to "lossy" to allow lossy conversion. If lossy conversion is
-	 * not allowed, full round-trip conversion is expected to work without losing information.
+	 * @param string $toModel The desired content model, use the CONTENT_MODEL_XXX flags.
+	 * @param string $lossy Optional flag, set to "lossy" to allow lossy conversion. If lossy
+	 * conversion is not allowed, full round-trip conversion is expected to work without losing
+	 * information.
 	 *
 	 * @return Content|bool A content object with the content model $toModel, or false if
 	 * that conversion is not supported.
 	 */
 	public function convert( $toModel, $lossy = '' );
-
-		// TODO: ImagePage and CategoryPage interfere with per-content action handlers
-	// TODO: nice&sane integration of GeSHi syntax highlighting
+	// @todo ImagePage and CategoryPage interfere with per-content action handlers
+	// @todo nice&sane integration of GeSHi syntax highlighting
 	//   [11:59] <vvv> Hooks are ugly; make CodeHighlighter interface and a
 	//   config to set the class which handles syntax highlighting
 	//   [12:00] <vvv> And default it to a DummyHighlighter
+
 }
diff --git a/includes/content/ContentHandler.php b/includes/content/ContentHandler.php
index 2a92e233..ac417223 100644
--- a/includes/content/ContentHandler.php
+++ b/includes/content/ContentHandler.php
@@ -31,7 +31,6 @@
  * @ingroup Content
  */
 class MWContentSerializationException extends MWException {
-
 }
 
 /**
@@ -54,7 +53,6 @@ class MWContentSerializationException extends MWException {
  * @ingroup Content
  */
 abstract class ContentHandler {
-
 	/**
 	 * Switch for enabling deprecation warnings. Used by ContentHandler::deprecated()
 	 * and ContentHandler::runLegacyHooks().
@@ -87,10 +85,11 @@ abstract class ContentHandler {
 	 *
 	 * @since 1.21
 	 *
-	 * @param $content Content|null
-	 * @return null|string the textual form of $content, if available
-	 * @throws MWException if $content is not an instance of TextContent and
-	 *   $wgContentHandlerTextFallback was set to 'fail'.
+	 * @param Content $content
+	 *
+	 * @throws MWException If the content is not an instance of TextContent and
+	 * wgContentHandlerTextFallback was set to 'fail'.
+	 * @return string|null Textual form of the content, if available.
 	 */
 	public static function getContentText( Content $content = null ) {
 		global $wgContentHandlerTextFallback;
@@ -129,24 +128,21 @@ abstract class ContentHandler {
 	 *
 	 * @since 1.21
 	 *
-	 * @param string $text the textual representation, will be
+	 * @param string $text The textual representation, will be
 	 *    unserialized to create the Content object
-	 * @param $title null|Title the title of the page this text belongs to.
+	 * @param Title $title The title of the page this text belongs to.
 	 *    Required if $modelId is not provided.
-	 * @param $modelId null|string the model to deserialize to. If not provided,
+	 * @param string $modelId The model to deserialize to. If not provided,
 	 *    $title->getContentModel() is used.
-	 * @param $format null|string the format to use for deserialization. If not
+	 * @param string $format The format to use for deserialization. If not
 	 *    given, the model's default format is used.
 	 *
-	 * @throws MWException
-	 * @return Content a Content object representing $text
-	 *
-	 * @throws MWException if $model or $format is not supported or if $text can
-	 *    not be unserialized using $format.
+	 * @throws MWException If model ID or format is not supported or if the text can not be
+	 * unserialized using the format.
+	 * @return Content A Content object representing the text.
 	 */
 	public static function makeContent( $text, Title $title = null,
-		$modelId = null, $format = null )
-	{
+		$modelId = null, $format = null ) {
 		if ( is_null( $modelId ) ) {
 			if ( is_null( $title ) ) {
 				throw new MWException( "Must provide a Title object or a content model ID." );
@@ -156,6 +152,7 @@ abstract class ContentHandler {
 		}
 
 		$handler = ContentHandler::getForModelID( $modelId );
+
 		return $handler->unserializeContent( $text, $format );
 	}
 
@@ -189,8 +186,9 @@ abstract class ContentHandler {
 	 *
 	 * @since 1.21
 	 *
-	 * @param $title Title
-	 * @return null|string default model name for the page given by $title
+	 * @param Title $title
+	 *
+	 * @return string Default model name for the page given by $title
 	 */
 	public static function getDefaultModelFor( Title $title ) {
 		// NOTE: this method must not rely on $title->getContentModel() directly or indirectly,
@@ -254,11 +252,13 @@ abstract class ContentHandler {
 	 *
 	 * @since 1.21
 	 *
-	 * @param $title Title
+	 * @param Title $title
+	 *
 	 * @return ContentHandler
 	 */
 	public static function getForTitle( Title $title ) {
 		$modelId = $title->getContentModel();
+
 		return ContentHandler::getForModelID( $modelId );
 	}
 
@@ -268,18 +268,20 @@ abstract class ContentHandler {
 	 *
 	 * @since 1.21
 	 *
-	 * @param $content Content
+	 * @param Content $content
+	 *
 	 * @return ContentHandler
 	 */
 	public static function getForContent( Content $content ) {
 		$modelId = $content->getModel();
+
 		return ContentHandler::getForModelID( $modelId );
 	}
 
 	/**
-	 * @var Array A Cache of ContentHandler instances by model id
+	 * @var array A Cache of ContentHandler instances by model id
 	 */
-	static $handlers;
+	protected static $handlers;
 
 	/**
 	 * Returns the ContentHandler singleton for the given model ID. Use the
@@ -302,9 +304,9 @@ abstract class ContentHandler {
 	 *
 	 * @param string $modelId The ID of the content model for which to get a
 	 *    handler. Use CONTENT_MODEL_XXX constants.
-	 * @return ContentHandler The ContentHandler singleton for handling the
-	 *    model given by $modelId
-	 * @throws MWException if no handler is known for $modelId.
+	 *
+	 * @throws MWException If no handler is known for the model ID.
+	 * @return ContentHandler The ContentHandler singleton for handling the model given by the ID.
 	 */
 	public static function getForModelID( $modelId ) {
 		global $wgContentHandlers;
@@ -330,14 +332,16 @@ abstract class ContentHandler {
 			$handler = new $class( $modelId );
 
 			if ( !( $handler instanceof ContentHandler ) ) {
-				throw new MWException( "$class from \$wgContentHandlers is not compatible with ContentHandler" );
+				throw new MWException( "$class from \$wgContentHandlers is not " .
+					"compatible with ContentHandler" );
 			}
 		}
 
 		wfDebugLog( 'ContentHandler', 'Created handler for ' . $modelId
-					. ': ' . get_class( $handler ) );
+			. ': ' . get_class( $handler ) );
 
 		ContentHandler::$handlers[$modelId] = $handler;
+
 		return ContentHandler::$handlers[$modelId];
 	}
 
@@ -350,10 +354,12 @@ abstract class ContentHandler {
 	 * @param string $name The content model ID, as given by a CONTENT_MODEL_XXX
 	 *    constant or returned by Revision::getContentModel().
 	 *
-	 * @return string The content format's localized name.
-	 * @throws MWException if the model id isn't known.
+	 * @throws MWException If the model ID isn't known.
+	 * @return string The content model's localized name.
 	 */
 	public static function getLocalizedName( $name ) {
+		// Messages: content-model-wikitext, content-model-text,
+		// content-model-javascript, content-model-css
 		$key = "content-model-$name";
 
 		$msg = wfMessage( $key );
@@ -378,12 +384,20 @@ abstract class ContentHandler {
 		}
 
 		$formats = array_unique( $formats );
+
 		return $formats;
 	}
 
 	// ------------------------------------------------------------------------
 
+	/**
+	 * @var string
+	 */
 	protected $mModelID;
+
+	/**
+	 * @var string[]
+	 */
 	protected $mSupportedFormats;
 
 	/**
@@ -392,7 +406,7 @@ abstract class ContentHandler {
 	 * provided as literals by subclass's constructors.
 	 *
 	 * @param string $modelId (use CONTENT_MODEL_XXX constants).
-	 * @param array $formats List for supported serialization formats
+	 * @param string[] $formats List for supported serialization formats
 	 *    (typically as MIME types)
 	 */
 	public function __construct( $modelId, $formats ) {
@@ -409,24 +423,55 @@ abstract class ContentHandler {
 	 *
 	 * @since 1.21
 	 *
-	 * @param $content Content The Content object to serialize
-	 * @param $format null|String The desired serialization format
+	 * @param Content $content The Content object to serialize
+	 * @param string $format The desired serialization format
+	 *
 	 * @return string Serialized form of the content
 	 */
 	abstract public function serializeContent( Content $content, $format = null );
 
 	/**
+	 * Applies transformations on export (returns the blob unchanged per default).
+	 * Subclasses may override this to perform transformations such as conversion
+	 * of legacy formats or filtering of internal meta-data.
+	 *
+	 * @param string $blob The blob to be exported
+	 * @param string|null $format The blob's serialization format
+	 *
+	 * @return string
+	 */
+	public function exportTransform( $blob, $format = null ) {
+		return $blob;
+	}
+
+	/**
 	 * Unserializes a Content object of the type supported by this ContentHandler.
 	 *
 	 * @since 1.21
 	 *
-	 * @param string $blob serialized form of the content
-	 * @param $format null|String the format used for serialization
-	 * @return Content the Content object created by deserializing $blob
+	 * @param string $blob Serialized form of the content
+	 * @param string $format The format used for serialization
+	 *
+	 * @return Content The Content object created by deserializing $blob
 	 */
 	abstract public function unserializeContent( $blob, $format = null );
 
 	/**
+	 * Apply import transformation (per default, returns $blob unchanged).
+	 * This gives subclasses an opportunity to transform data blobs on import.
+	 *
+	 * @since 1.24
+	 *
+	 * @param string $blob
+	 * @param string|null $format
+	 *
+	 * @return string
+	 */
+	public function importTransform( $blob, $format = null ) {
+		return $blob;
+	}
+
+	/**
 	 * Creates an empty Content object of the type supported by this
 	 * ContentHandler.
 	 *
@@ -438,7 +483,7 @@ abstract class ContentHandler {
 
 	/**
 	 * Creates a new Content object that acts as a redirect to the given page,
-	 * or null of redirects are not supported by this content model.
+	 * or null if redirects are not supported by this content model.
 	 *
 	 * This default implementation always returns null. Subclasses supporting redirects
 	 * must override this method.
@@ -448,10 +493,10 @@ abstract class ContentHandler {
 	 *
 	 * @since 1.21
 	 *
-	 * @param Title $destination the page to redirect to.
-	 * @param string $text text to include in the redirect, if possible.
+	 * @param Title $destination The page to redirect to.
+	 * @param string $text Text to include in the redirect, if possible.
 	 *
-	 * @return Content
+	 * @return Content Always null.
 	 */
 	public function makeRedirectContent( Title $destination, $text = '' ) {
 		return null;
@@ -463,21 +508,19 @@ abstract class ContentHandler {
 	 *
 	 * @since 1.21
 	 *
-	 * @return String The model ID
+	 * @return string The model ID
 	 */
 	public function getModelID() {
 		return $this->mModelID;
 	}
 
 	/**
-	 * Throws an MWException if $model_id is not the ID of the content model
-	 * supported by this ContentHandler.
-	 *
 	 * @since 1.21
 	 *
 	 * @param string $model_id The model to check
 	 *
-	 * @throws MWException
+	 * @throws MWException If the model ID is not the ID of the content model supported by this
+	 * ContentHandler.
 	 */
 	protected function checkModelID( $model_id ) {
 		if ( $model_id !== $this->mModelID ) {
@@ -494,7 +537,7 @@ abstract class ContentHandler {
 	 *
 	 * @since 1.21
 	 *
-	 * @return array of serialization formats as MIME type like strings
+	 * @return string[] List of serialization formats as MIME type like strings
 	 */
 	public function getSupportedFormats() {
 		return $this->mSupportedFormats;
@@ -509,7 +552,7 @@ abstract class ContentHandler {
 	 *
 	 * @since 1.21
 	 *
-	 * @return string the name of the default serialization format as a MIME type
+	 * @return string The name of the default serialization format as a MIME type
 	 */
 	public function getDefaultFormat() {
 		return $this->mSupportedFormats[0];
@@ -524,11 +567,11 @@ abstract class ContentHandler {
 	 *
 	 * @since 1.21
 	 *
-	 * @param string $format the serialization format to check
+	 * @param string $format The serialization format to check
+	 *
 	 * @return bool
 	 */
 	public function isSupportedFormat( $format ) {
-
 		if ( !$format ) {
 			return true; // this means "use the default"
 		}
@@ -537,13 +580,11 @@ abstract class ContentHandler {
 	}
 
 	/**
-	 * Throws an MWException if isSupportedFormat( $format ) is not true.
-	 * Convenient for checking whether a format provided as a parameter is
-	 * actually supported.
+	 * Convenient for checking whether a format provided as a parameter is actually supported.
 	 *
-	 * @param string $format the serialization format to check
+	 * @param string $format The serialization format to check
 	 *
-	 * @throws MWException
+	 * @throws MWException If the format is not supported by this content handler.
 	 */
 	protected function checkFormat( $format ) {
 		if ( !$this->isSupportedFormat( $format ) ) {
@@ -562,7 +603,7 @@ abstract class ContentHandler {
 	 *
 	 * @since 1.21
 	 *
-	 * @return Array
+	 * @return array Always an empty array.
 	 */
 	public function getActionOverrides() {
 		return array();
@@ -573,21 +614,18 @@ abstract class ContentHandler {
 	 *
 	 * @since 1.21
 	 *
-	 * @param $context IContextSource context to use, anything else will be
-	 *    ignored
-	 * @param $old Integer Old ID we want to show and diff with.
-	 * @param int|string $new String either 'prev' or 'next'.
-	 * @param $rcid Integer ??? FIXME (default 0)
-	 * @param $refreshCache boolean If set, refreshes the diff cache
-	 * @param $unhide boolean If set, allow viewing deleted revs
+	 * @param IContextSource $context Context to use, anything else will be ignored.
+	 * @param int $old Revision ID we want to show and diff with.
+	 * @param int|string $new Either a revision ID or one of the strings 'cur', 'prev' or 'next'.
+	 * @param int $rcid FIXME: Deprecated, no longer used. Defaults to 0.
+	 * @param bool $refreshCache If set, refreshes the diff cache. Defaults to false.
+	 * @param bool $unhide If set, allow viewing deleted revs. Defaults to false.
 	 *
 	 * @return DifferenceEngine
 	 */
-	public function createDifferenceEngine( IContextSource $context,
-		$old = 0, $new = 0,
-		$rcid = 0, # FIXME: use everywhere!
-		$refreshCache = false, $unhide = false
-	) {
+	public function createDifferenceEngine( IContextSource $context, $old = 0, $new = 0,
+		$rcid = 0, //FIXME: Deprecated, no longer used
+		$refreshCache = false, $unhide = false ) {
 		$diffEngineClass = $this->getDiffEngineClass();
 
 		return new $diffEngineClass( $context, $old, $new, $rcid, $refreshCache, $unhide );
@@ -596,19 +634,21 @@ abstract class ContentHandler {
 	/**
 	 * Get the language in which the content of the given page is written.
 	 *
-	 * This default implementation just returns $wgContLang (except for pages in the MediaWiki namespace)
+	 * This default implementation just returns $wgContLang (except for pages
+	 * in the MediaWiki namespace)
 	 *
-	 * Note that the pages language is not cacheable, since it may in some cases depend on user settings.
+	 * Note that the pages language is not cacheable, since it may in some
+	 * cases depend on user settings.
 	 *
 	 * Also note that the page language may or may not depend on the actual content of the page,
 	 * that is, this method may load the content in order to determine the language.
 	 *
 	 * @since 1.21
 	 *
-	 * @param Title        $title the page to determine the language for.
-	 * @param Content|null $content the page's content, if you have it handy, to avoid reloading it.
+	 * @param Title $title The page to determine the language for.
+	 * @param Content $content The page's content, if you have it handy, to avoid reloading it.
 	 *
-	 * @return Language the page's language
+	 * @return Language The page's language
 	 */
 	public function getPageLanguage( Title $title, Content $content = null ) {
 		global $wgContLang, $wgLang;
@@ -621,6 +661,7 @@ abstract class ContentHandler {
 		}
 
 		wfRunHooks( 'PageContentLanguage', array( $title, &$pageLang, $wgLang ) );
+
 		return wfGetLangObj( $pageLang );
 	}
 
@@ -639,10 +680,10 @@ abstract class ContentHandler {
 	 *
 	 * @since 1.21
 	 *
-	 * @param Title        $title the page to determine the language for.
-	 * @param Content|null $content the page's content, if you have it handy, to avoid reloading it.
+	 * @param Title $title The page to determine the language for.
+	 * @param Content $content The page's content, if you have it handy, to avoid reloading it.
 	 *
-	 * @return Language the page's language for viewing
+	 * @return Language The page's language for viewing
 	 */
 	public function getPageViewLanguage( Title $title, Content $content = null ) {
 		$pageLang = $this->getPageLanguage( $title, $content );
@@ -668,12 +709,19 @@ abstract class ContentHandler {
 	 * typically based on the namespace or some other aspect of the title, such as a special suffix
 	 * (e.g. ".svg" for SVG content).
 	 *
-	 * @param Title $title the page's title.
+	 * @note this calls the ContentHandlerCanBeUsedOn hook which may be used to override which
+	 * content model can be used where.
 	 *
-	 * @return bool true if content of this kind can be used on the given page, false otherwise.
+	 * @param Title $title The page's title.
+	 *
+	 * @return bool True if content of this kind can be used on the given page, false otherwise.
 	 */
 	public function canBeUsedOn( Title $title ) {
-		return true;
+		$ok = true;
+
+		wfRunHooks( 'ContentModelCanBeUsedOn', array( $this->getModelID(), $title, &$ok ) );
+
+		return $ok;
 	}
 
 	/**
@@ -688,19 +736,18 @@ abstract class ContentHandler {
 	}
 
 	/**
-	 * Attempts to merge differences between three versions.
-	 * Returns a new Content object for a clean merge and false for failure or
-	 * a conflict.
+	 * Attempts to merge differences between three versions. Returns a new
+	 * Content object for a clean merge and false for failure or a conflict.
 	 *
 	 * This default implementation always returns false.
 	 *
 	 * @since 1.21
 	 *
-	 * @param $oldContent Content|string  String
-	 * @param $myContent Content|string   String
-	 * @param $yourContent Content|string String
+	 * @param Content $oldContent The page's previous content.
+	 * @param Content $myContent One of the page's conflicting contents.
+	 * @param Content $yourContent One of the page's conflicting contents.
 	 *
-	 * @return Content|Bool
+	 * @return Content|bool Always false.
 	 */
 	public function merge3( Content $oldContent, Content $myContent, Content $yourContent ) {
 		return false;
@@ -711,13 +758,14 @@ abstract class ContentHandler {
 	 *
 	 * @since 1.21
 	 *
-	 * @param $oldContent Content|null: the previous text of the page.
-	 * @param $newContent Content|null: The submitted text of the page.
+	 * @param Content $oldContent The previous text of the page.
+	 * @param Content $newContent The submitted text of the page.
 	 * @param int $flags Bit mask: a bit mask of flags submitted for the edit.
 	 *
 	 * @return string An appropriate auto-summary, or an empty string.
 	 */
-	public function getAutosummary( Content $oldContent = null, Content $newContent = null, $flags ) {
+	public function getAutosummary( Content $oldContent = null, Content $newContent = null,
+		$flags ) {
 		// Decide what kind of auto-summary is needed.
 
 		// Redirect auto-summaries
@@ -733,15 +781,15 @@ abstract class ContentHandler {
 		if ( is_object( $rt ) ) {
 			if ( !is_object( $ot )
 				|| !$rt->equals( $ot )
-				|| $ot->getFragment() != $rt->getFragment() )
-			{
+				|| $ot->getFragment() != $rt->getFragment()
+			) {
 				$truncatedtext = $newContent->getTextForSummary(
 					250
-						- strlen( wfMessage( 'autoredircomment' )->inContentLanguage()->text() )
-						- strlen( $rt->getFullText() ) );
+					- strlen( wfMessage( 'autoredircomment' )->inContentLanguage()->text() )
+					- strlen( $rt->getFullText() ) );
 
 				return wfMessage( 'autoredircomment', $rt->getFullText() )
-						->rawParams( $truncatedtext )->inContentLanguage()->text();
+					->rawParams( $truncatedtext )->inContentLanguage()->text();
 			}
 		}
 
@@ -754,7 +802,7 @@ abstract class ContentHandler {
 				200 - strlen( wfMessage( 'autosumm-new' )->inContentLanguage()->text() ) );
 
 			return wfMessage( 'autosumm-new' )->rawParams( $truncatedtext )
-					->inContentLanguage()->text();
+				->inContentLanguage()->text();
 		}
 
 		// Blanking auto-summaries
@@ -762,15 +810,20 @@ abstract class ContentHandler {
 			return wfMessage( 'autosumm-blank' )->inContentLanguage()->text();
 		} elseif ( !empty( $oldContent )
 			&& $oldContent->getSize() > 10 * $newContent->getSize()
-			&& $newContent->getSize() < 500 )
-		{
+			&& $newContent->getSize() < 500
+		) {
 			// Removing more than 90% of the article
 
 			$truncatedtext = $newContent->getTextForSummary(
 				200 - strlen( wfMessage( 'autosumm-replace' )->inContentLanguage()->text() ) );
 
 			return wfMessage( 'autosumm-replace' )->rawParams( $truncatedtext )
-					->inContentLanguage()->text();
+				->inContentLanguage()->text();
+		}
+
+		// New blank article auto-summary
+		if ( $flags & EDIT_NEW && $newContent->isEmpty() ) {
+			return wfMessage( 'autosumm-newblank' )->inContentLanguage()->text();
 		}
 
 		// If we reach this point, there's no applicable auto-summary for our
@@ -783,12 +836,13 @@ abstract class ContentHandler {
 	 *
 	 * @since 1.21
 	 *
-	 * @param $title Title: the page's title
-	 * @param &$hasHistory Boolean: whether the page has a history
+	 * @param Title $title The page's title
+	 * @param bool &$hasHistory Whether the page has a history
+	 *
 	 * @return mixed String containing deletion reason or empty string, or
 	 *    boolean false if no revision occurred
 	 *
-	 * @XXX &$hasHistory is extremely ugly, it's here because
+	 * @todo &$hasHistory is extremely ugly, it's here because
 	 * WikiPage::getAutoDeleteReason() and Article::generateReason()
 	 * have it / want it.
 	 */
@@ -891,9 +945,9 @@ abstract class ContentHandler {
 	 *
 	 * @since 1.21
 	 *
-	 * @param $current Revision The current text
-	 * @param $undo Revision The revision to undo
-	 * @param $undoafter Revision Must be an earlier revision than $undo
+	 * @param Revision $current The current text
+	 * @param Revision $undo The revision to undo
+	 * @param Revision $undoafter Must be an earlier revision than $undo
 	 *
 	 * @return mixed String on success, false on failure
 	 */
@@ -907,6 +961,10 @@ abstract class ContentHandler {
 		$undo_content = $undo->getContent();
 		$undoafter_content = $undoafter->getContent();
 
+		if ( !$undo_content || !$undoafter_content ) {
+			return false; // no content to undo
+		}
+
 		$this->checkModelID( $cur_content->getModel() );
 		$this->checkModelID( $undo_content->getModel() );
 		$this->checkModelID( $undoafter_content->getModel() );
@@ -922,7 +980,7 @@ abstract class ContentHandler {
 	}
 
 	/**
-	 * Get parser options suitable for rendering the primary article wikitext
+	 * Get parser options suitable for rendering and caching the article
 	 *
 	 * @param IContextSource|User|string $context One of the following:
 	 *        - IContextSource: Use the User and the Language of the provided
@@ -932,8 +990,6 @@ abstract class ContentHandler {
 	 *        - 'canonical': Canonical options (anonymous user with default
 	 *                                            preferences and content language).
 	 *
-	 * @param IContextSource|User|string $context
-	 *
 	 * @throws MWException
 	 * @return ParserOptions
 	 */
@@ -962,7 +1018,7 @@ abstract class ContentHandler {
 	 *
 	 * @since 1.21
 	 *
-	 * @return bool
+	 * @return bool Always false.
 	 */
 	public function isParserCacheSupported() {
 		return false;
@@ -975,7 +1031,7 @@ abstract class ContentHandler {
 	 * Content models that return true here should also implement
 	 * Content::getSection, Content::replaceSection, etc. to handle sections..
 	 *
-	 * @return boolean whether sections are supported.
+	 * @return bool Always false.
 	 */
 	public function supportsSections() {
 		return false;
@@ -988,7 +1044,7 @@ abstract class ContentHandler {
 	 * Content models that return true here should also implement
 	 * ContentHandler::makeRedirectContent to return a Content object.
 	 *
-	 * @return boolean whether redirects are supported.
+	 * @return bool Always false.
 	 */
 	public function supportsRedirects() {
 		return false;
@@ -998,11 +1054,11 @@ abstract class ContentHandler {
 	 * Logs a deprecation warning, visible if $wgDevelopmentWarnings, but only if
 	 * self::$enableDeprecationWarnings is set to true.
 	 *
-	 * @param string      $func The name of the deprecated function
-	 * @param string      $version The version since the method is deprecated. Usually 1.21
-	 *                    for ContentHandler related stuff.
-	 * @param string|bool $component: Component to which the function belongs.
-	 *                                If false, it is assumed the function is in MediaWiki core.
+	 * @param string $func The name of the deprecated function
+	 * @param string $version The version since the method is deprecated. Usually 1.21
+	 *   for ContentHandler related stuff.
+	 * @param string|bool $component : Component to which the function belongs.
+	 *   If false, it is assumed the function is in MediaWiki core.
 	 *
 	 * @see ContentHandler::$enableDeprecationWarnings
 	 * @see wfDeprecated
@@ -1020,18 +1076,19 @@ abstract class ContentHandler {
 	 * hook function, a new Content object is constructed from the new
 	 * text.
 	 *
-	 * @param string $event event name
-	 * @param array $args parameters passed to hook functions
-	 * @param bool $warn whether to log a warning.
+	 * @param string $event Event name
+	 * @param array $args Parameters passed to hook functions
+	 * @param bool $warn Whether to log a warning.
 	 *                    Default to self::$enableDeprecationWarnings.
 	 *                    May be set to false for testing.
 	 *
-	 * @return Boolean True if no handler aborted the hook
+	 * @return bool True if no handler aborted the hook
 	 *
 	 * @see ContentHandler::$enableDeprecationWarnings
 	 */
 	public static function runLegacyHooks( $event, $args = array(),
-			$warn = null ) {
+		$warn = null
+	) {
 
 		if ( $warn === null ) {
 			$warn = self::$enableDeprecationWarnings;
@@ -1073,7 +1130,8 @@ abstract class ContentHandler {
 
 			wfRestoreWarnings();
 
-			wfWarn( "Using obsolete hook $event via ContentHandler::runLegacyHooks()! Handlers: " . implode( ', ', $handlerInfo ), 2 );
+			wfWarn( "Using obsolete hook $event via ContentHandler::runLegacyHooks()! Handlers: " .
+				implode( ', ', $handlerInfo ), 2 );
 		}
 
 		// convert Content objects to text
diff --git a/includes/content/CssContent.php b/includes/content/CssContent.php
index 03cc2d00..8290603c 100644
--- a/includes/content/CssContent.php
+++ b/includes/content/CssContent.php
@@ -31,18 +31,26 @@
  * @ingroup Content
  */
 class CssContent extends TextContent {
-	public function __construct( $text ) {
-		parent::__construct( $text, CONTENT_MODEL_CSS );
+
+	/**
+	 * @param string $text CSS code.
+	 * @param string $modelId the content content model
+	 */
+	public function __construct( $text, $modelId = CONTENT_MODEL_CSS ) {
+		parent::__construct( $text, $modelId );
 	}
 
 	/**
 	 * Returns a Content object with pre-save transformations applied using
 	 * Parser::preSaveTransform().
 	 *
-	 * @param $title Title
-	 * @param $user User
-	 * @param $popts ParserOptions
-	 * @return Content
+	 * @param Title $title
+	 * @param User $user
+	 * @param ParserOptions $popts
+	 *
+	 * @return CssContent
+	 *
+	 * @see TextContent::preSaveTransform
 	 */
 	public function preSaveTransform( Title $title, User $user, ParserOptions $popts ) {
 		global $wgParser;
@@ -51,15 +59,19 @@ class CssContent extends TextContent {
 		$text = $this->getNativeData();
 		$pst = $wgParser->preSaveTransform( $text, $title, $user, $popts );
 
-		return new CssContent( $pst );
+		return new static( $pst );
 	}
 
+	/**
+	 * @return string CSS wrapped in a <pre> tag.
+	 */
 	protected function getHtml() {
 		$html = "";
 		$html .= "<pre class=\"mw-code mw-css\" dir=\"ltr\">\n";
-		$html .= $this->getHighlightHtml();
+		$html .= htmlspecialchars( $this->getNativeData() );
 		$html .= "\n</pre>\n";
 
 		return $html;
 	}
+
 }
diff --git a/includes/content/CssContentHandler.php b/includes/content/CssContentHandler.php
index cb5a349d..b2a8676b 100644
--- a/includes/content/CssContentHandler.php
+++ b/includes/content/CssContentHandler.php
@@ -27,41 +27,16 @@
  * @since 1.21
  * @ingroup Content
  */
-class CssContentHandler extends TextContentHandler {
-
-	public function __construct( $modelId = CONTENT_MODEL_CSS ) {
-		parent::__construct( $modelId, array( CONTENT_FORMAT_CSS ) );
-	}
-
-	public function unserializeContent( $text, $format = null ) {
-		$this->checkFormat( $format );
-
-		return new CssContent( $text );
-	}
-
-	public function makeEmptyContent() {
-		return new CssContent( '' );
-	}
+class CssContentHandler extends CodeContentHandler {
 
 	/**
-	 * Returns the english language, because CSS is english, and should be handled as such.
-	 *
-	 * @return Language wfGetLangObj( 'en' )
-	 *
-	 * @see ContentHandler::getPageLanguage()
+	 * @param string $modelId
 	 */
-	public function getPageLanguage( Title $title, Content $content = null ) {
-		return wfGetLangObj( 'en' );
+	public function __construct( $modelId = CONTENT_MODEL_CSS ) {
+		parent::__construct( $modelId, array( CONTENT_FORMAT_CSS ) );
 	}
 
-	/**
-	 * Returns the english language, because CSS is english, and should be handled as such.
-	 *
-	 * @return Language wfGetLangObj( 'en' )
-	 *
-	 * @see ContentHandler::getPageViewLanguage()
-	 */
-	public function getPageViewLanguage( Title $title, Content $content = null ) {
-		return wfGetLangObj( 'en' );
+	protected function getContentClass() {
+		return 'CssContent';
 	}
 }
diff --git a/includes/content/JavaScriptContent.php b/includes/content/JavaScriptContent.php
index 2ae572be..c0194c2e 100644
--- a/includes/content/JavaScriptContent.php
+++ b/includes/content/JavaScriptContent.php
@@ -31,8 +31,13 @@
  * @ingroup Content
  */
 class JavaScriptContent extends TextContent {
-	public function __construct( $text ) {
-		parent::__construct( $text, CONTENT_MODEL_JAVASCRIPT );
+
+	/**
+	 * @param string $text JavaScript code.
+	 * @param string $modelId the content model name
+	 */
+	public function __construct( $text, $modelId = CONTENT_MODEL_JAVASCRIPT ) {
+		parent::__construct( $text, $modelId );
 	}
 
 	/**
@@ -42,7 +47,8 @@ class JavaScriptContent extends TextContent {
 	 * @param Title $title
 	 * @param User $user
 	 * @param ParserOptions $popts
-	 * @return Content
+	 *
+	 * @return JavaScriptContent
 	 */
 	public function preSaveTransform( Title $title, User $user, ParserOptions $popts ) {
 		global $wgParser;
@@ -52,15 +58,19 @@ class JavaScriptContent extends TextContent {
 		$text = $this->getNativeData();
 		$pst = $wgParser->preSaveTransform( $text, $title, $user, $popts );
 
-		return new JavaScriptContent( $pst );
+		return new static( $pst );
 	}
 
+	/**
+	 * @return string JavaScript wrapped in a <pre> tag.
+	 */
 	protected function getHtml() {
 		$html = "";
 		$html .= "<pre class=\"mw-code mw-js\" dir=\"ltr\">\n";
-		$html .= $this->getHighlightHtml();
+		$html .= htmlspecialchars( $this->getNativeData() );
 		$html .= "\n</pre>\n";
 
 		return $html;
 	}
+
 }
diff --git a/includes/content/JavaScriptContentHandler.php b/includes/content/JavaScriptContentHandler.php
index 33fa9172..457b83d7 100644
--- a/includes/content/JavaScriptContentHandler.php
+++ b/includes/content/JavaScriptContentHandler.php
@@ -27,41 +27,16 @@
  * @ingroup Content
  * @todo make ScriptContentHandler base class, do highlighting stuff there?
  */
-class JavaScriptContentHandler extends TextContentHandler {
-
-	public function __construct( $modelId = CONTENT_MODEL_JAVASCRIPT ) {
-		parent::__construct( $modelId, array( CONTENT_FORMAT_JAVASCRIPT ) );
-	}
-
-	public function unserializeContent( $text, $format = null ) {
-		$this->checkFormat( $format );
-
-		return new JavaScriptContent( $text );
-	}
-
-	public function makeEmptyContent() {
-		return new JavaScriptContent( '' );
-	}
+class JavaScriptContentHandler extends CodeContentHandler {
 
 	/**
-	 * Returns the english language, because JS is english, and should be handled as such.
-	 *
-	 * @return Language wfGetLangObj( 'en' )
-	 *
-	 * @see ContentHandler::getPageLanguage()
+	 * @param string $modelId
 	 */
-	public function getPageLanguage( Title $title, Content $content = null ) {
-		return wfGetLangObj( 'en' );
+	public function __construct( $modelId = CONTENT_MODEL_JAVASCRIPT ) {
+		parent::__construct( $modelId, array( CONTENT_FORMAT_JAVASCRIPT ) );
 	}
 
-	/**
-	 * Returns the english language, because JS is english, and should be handled as such.
-	 *
-	 * @return Language wfGetLangObj( 'en' )
-	 *
-	 * @see ContentHandler::getPageViewLanguage()
-	 */
-	public function getPageViewLanguage( Title $title, Content $content = null ) {
-		return wfGetLangObj( 'en' );
+	protected function getContentClass() {
+		return 'JavaScriptContent';
 	}
 }
diff --git a/includes/content/JsonContent.php b/includes/content/JsonContent.php
new file mode 100644
index 00000000..b36827c5
--- /dev/null
+++ b/includes/content/JsonContent.php
@@ -0,0 +1,120 @@
+<?php
+/**
+ * JSON Content Model
+ *
+ * @file
+ *
+ * @author Ori Livneh <ori@wikimedia.org>
+ * @author Kunal Mehta <legoktm@gmail.com>
+ */
+
+/**
+ * Represents the content of a JSON content.
+ * @since 1.24
+ */
+class JsonContent extends TextContent {
+
+	public function __construct( $text, $modelId = CONTENT_MODEL_JSON ) {
+		parent::__construct( $text, $modelId );
+	}
+
+	/**
+	 * Decodes the JSON into a PHP associative array.
+	 * @return array
+	 */
+	public function getJsonData() {
+		return FormatJson::decode( $this->getNativeData(), true );
+	}
+
+	/**
+	 * @return bool Whether content is valid JSON.
+	 */
+	public function isValid() {
+		return $this->getJsonData() !== null;
+	}
+
+	/**
+	 * Pretty-print JSON
+	 *
+	 * @return bool|null|string
+	 */
+	public function beautifyJSON() {
+		$decoded = FormatJson::decode( $this->getNativeData(), true );
+		if ( !is_array( $decoded ) ) {
+			return null;
+		}
+		return FormatJson::encode( $decoded, true );
+
+	}
+
+	/**
+	 * Beautifies JSON prior to save.
+	 * @param Title $title Title
+	 * @param User $user User
+	 * @param ParserOptions $popts
+	 * @return JsonContent
+	 */
+	public function preSaveTransform( Title $title, User $user, ParserOptions $popts ) {
+		return new static( $this->beautifyJSON() );
+	}
+
+	/**
+	 * Set the HTML and add the appropriate styles
+	 *
+	 *
+	 * @param Title $title
+	 * @param int $revId
+	 * @param ParserOptions $options
+	 * @param bool $generateHtml
+	 * @param ParserOutput $output
+	 */
+	protected function fillParserOutput( Title $title, $revId,
+		ParserOptions $options, $generateHtml, ParserOutput &$output
+	) {
+		if ( $generateHtml ) {
+			$output->setText( $this->objectTable( $this->getJsonData() ) );
+			$output->addModuleStyles( 'mediawiki.content.json' );
+		} else {
+			$output->setText( '' );
+		}
+	}
+	/**
+	 * Constructs an HTML representation of a JSON object.
+	 * @param array $mapping
+	 * @return string HTML
+	 */
+	protected function objectTable( $mapping ) {
+		$rows = array();
+
+		foreach ( $mapping as $key => $val ) {
+			$rows[] = $this->objectRow( $key, $val );
+		}
+		return Xml::tags( 'table', array( 'class' => 'mw-json' ),
+			Xml::tags( 'tbody', array(), join( "\n", $rows ) )
+		);
+	}
+
+	/**
+	 * Constructs HTML representation of a single key-value pair.
+	 * @param string $key
+	 * @param mixed $val
+	 * @return string HTML.
+	 */
+	protected function objectRow( $key, $val ) {
+		$th = Xml::elementClean( 'th', array(), $key );
+		if ( is_array( $val ) ) {
+			$td = Xml::tags( 'td', array(), self::objectTable( $val ) );
+		} else {
+			if ( is_string( $val ) ) {
+				$val = '"' . $val . '"';
+			} else {
+				$val = FormatJson::encode( $val );
+			}
+
+			$td = Xml::elementClean( 'td', array( 'class' => 'value' ), $val );
+		}
+
+		return Xml::tags( 'tr', array(), $th . $td );
+	}
+
+}
diff --git a/includes/content/JsonContentHandler.php b/includes/content/JsonContentHandler.php
new file mode 100644
index 00000000..392ce37b
--- /dev/null
+++ b/includes/content/JsonContentHandler.php
@@ -0,0 +1,26 @@
+<?php
+/**
+ * JSON Schema Content Handler
+ *
+ * @file
+ *
+ * @author Ori Livneh <ori@wikimedia.org>
+ * @author Kunal Mehta <legoktm@gmail.com>
+ */
+
+/**
+ * @since 1.24
+ */
+class JsonContentHandler extends CodeContentHandler {
+
+	public function __construct( $modelId = CONTENT_MODEL_JSON ) {
+		parent::__construct( $modelId, array( CONTENT_FORMAT_JSON ) );
+	}
+
+	/**
+	 * @return string
+	 */
+	protected function getContentClass() {
+		return 'JsonContent';
+	}
+}
diff --git a/includes/content/MessageContent.php b/includes/content/MessageContent.php
index b36b670c..5b84657f 100644
--- a/includes/content/MessageContent.php
+++ b/includes/content/MessageContent.php
@@ -29,7 +29,7 @@
  * Wrapper allowing us to handle a system message as a Content object.
  * Note that this is generally *not* used to represent content from the
  * MediaWiki namespace, and that there is no MessageContentHandler.
- * MessageContent is just intended as glue for wrapping a message programatically.
+ * MessageContent is just intended as glue for wrapping a message programmatically.
  *
  * @ingroup Content
  */
@@ -41,8 +41,8 @@ class MessageContent extends AbstractContent {
 	protected $mMessage;
 
 	/**
-	 * @param Message|String $msg    A Message object, or a message key
-	 * @param array|null     $params An optional array of message parameters
+	 * @param Message|string $msg A Message object, or a message key.
+	 * @param string[] $params An optional array of message parameters.
 	 */
 	public function __construct( $msg, $params = null ) {
 		# XXX: messages may be wikitext, html or plain text! and maybe even something else entirely.
@@ -60,18 +60,18 @@ class MessageContent extends AbstractContent {
 	}
 
 	/**
-	 * Returns the message as rendered HTML
+	 * Fully parse the text from wikitext to HTML.
 	 *
-	 * @return string The message text, parsed into html
+	 * @return string Parsed HTML.
 	 */
 	public function getHtml() {
 		return $this->mMessage->parse();
 	}
 
 	/**
-	 * Returns the message as rendered HTML
+	 * Returns the message text. {{-transformation is done.
 	 *
-	 * @return string The message text, parsed into html
+	 * @return string Unescaped message text.
 	 */
 	public function getWikitext() {
 		return $this->mMessage->text();
@@ -88,6 +88,8 @@ class MessageContent extends AbstractContent {
 	}
 
 	/**
+	 * @return string
+	 *
 	 * @see Content::getTextForSearchIndex
 	 */
 	public function getTextForSearchIndex() {
@@ -95,6 +97,8 @@ class MessageContent extends AbstractContent {
 	}
 
 	/**
+	 * @return string
+	 *
 	 * @see Content::getWikitextForTransclusion
 	 */
 	public function getWikitextForTransclusion() {
@@ -102,6 +106,10 @@ class MessageContent extends AbstractContent {
 	}
 
 	/**
+	 * @param int $maxlength Maximum length of the summary text, defaults to 250.
+	 *
+	 * @return string The summary text.
+	 *
 	 * @see Content::getTextForSummary
 	 */
 	public function getTextForSummary( $maxlength = 250 ) {
@@ -109,18 +117,18 @@ class MessageContent extends AbstractContent {
 	}
 
 	/**
-	 * @see Content::getSize
-	 *
 	 * @return int
+	 *
+	 * @see Content::getSize
 	 */
 	public function getSize() {
 		return strlen( $this->mMessage->plain() );
 	}
 
 	/**
-	 * @see Content::copy
+	 * @return Content A copy of this object
 	 *
-	 * @return Content. A copy of this object
+	 * @see Content::copy
 	 */
 	public function copy() {
 		// MessageContent is immutable (because getNativeData() returns a clone of the Message object)
@@ -128,24 +136,28 @@ class MessageContent extends AbstractContent {
 	}
 
 	/**
-	 * @see Content::isCountable
+	 * @param bool $hasLinks
+	 *
+	 * @return bool Always false.
 	 *
-	 * @return bool false
+	 * @see Content::isCountable
 	 */
 	public function isCountable( $hasLinks = null ) {
 		return false;
 	}
 
 	/**
-	 * @see Content::getParserOutput
+	 * @param Title $title Unused.
+	 * @param int $revId Unused.
+	 * @param ParserOptions $options Unused.
+	 * @param bool $generateHtml Whether to generate HTML (default: true).
 	 *
 	 * @return ParserOutput
+	 *
+	 * @see Content::getParserOutput
 	 */
-	public function getParserOutput(
-		Title $title, $revId = null,
-		ParserOptions $options = null, $generateHtml = true
-	) {
-
+	public function getParserOutput( Title $title, $revId = null,
+		ParserOptions $options = null, $generateHtml = true ) {
 		if ( $generateHtml ) {
 			$html = $this->getHtml();
 		} else {
@@ -153,6 +165,10 @@ class MessageContent extends AbstractContent {
 		}
 
 		$po = new ParserOutput( $html );
+		// Message objects are in the user language.
+		$po->recordOption( 'userlang' );
+
 		return $po;
 	}
+
 }
diff --git a/includes/content/TextContent.php b/includes/content/TextContent.php
index f66dacd7..c479f202 100644
--- a/includes/content/TextContent.php
+++ b/includes/content/TextContent.php
@@ -34,12 +34,16 @@
  */
 class TextContent extends AbstractContent {
 
+	/**
+	 * @param string $text
+	 * @param string $model_id
+	 */
 	public function __construct( $text, $model_id = CONTENT_MODEL_TEXT ) {
 		parent::__construct( $model_id );
 
 		if ( $text === null || $text === false ) {
 			wfWarn( "TextContent constructed with \$text = " . var_export( $text, true ) . "! "
-					. "This may indicate an error in the caller's scope." );
+				. "This may indicate an error in the caller's scope.", 2 );
 
 			$text = '';
 		}
@@ -51,6 +55,11 @@ class TextContent extends AbstractContent {
 		$this->mText = $text;
 	}
 
+	/**
+	 * @note Mutable subclasses MUST override this to return a copy!
+	 *
+	 * @return Content $this
+	 */
 	public function copy() {
 		return $this; # NOTE: this is ok since TextContent are immutable.
 	}
@@ -68,12 +77,13 @@ class TextContent extends AbstractContent {
 	}
 
 	/**
-	 * returns the text's size in bytes.
+	 * Returns the text's size in bytes.
 	 *
-	 * @return int The size
+	 * @return int
 	 */
 	public function getSize() {
 		$text = $this->getNativeData();
+
 		return strlen( $text );
 	}
 
@@ -81,10 +91,10 @@ class TextContent extends AbstractContent {
 	 * Returns true if this content is not a redirect, and $wgArticleCountMethod
 	 * is "any".
 	 *
-	 * @param bool $hasLinks if it is known whether this content contains links,
+	 * @param bool $hasLinks If it is known whether this content contains links,
 	 * provide this information here, to avoid redundant parsing to find out.
 	 *
-	 * @return bool True if the content is countable
+	 * @return bool
 	 */
 	public function isCountable( $hasLinks = null ) {
 		global $wgArticleCountMethod;
@@ -103,17 +113,16 @@ class TextContent extends AbstractContent {
 	/**
 	 * Returns the text represented by this Content object, as a string.
 	 *
-	 * @return string: the raw text
+	 * @return string The raw text.
 	 */
 	public function getNativeData() {
-		$text = $this->mText;
-		return $text;
+		return $this->mText;
 	}
 
 	/**
 	 * Returns the text represented by this Content object, as a string.
 	 *
-	 * @return string: the raw text
+	 * @return string The raw text.
 	 */
 	public function getTextForSearchIndex() {
 		return $this->getNativeData();
@@ -123,9 +132,9 @@ class TextContent extends AbstractContent {
 	 * Returns attempts to convert this content object to wikitext,
 	 * and then returns the text string. The conversion may be lossy.
 	 *
-	 * @note: this allows any text-based content to be transcluded as if it was wikitext.
+	 * @note this allows any text-based content to be transcluded as if it was wikitext.
 	 *
-	 * @return string|false: the raw text, or null if the conversion failed
+	 * @return string|bool The raw text, or false if the conversion failed.
 	 */
 	public function getWikitextForTransclusion() {
 		$wikitext = $this->convert( CONTENT_MODEL_WIKITEXT, 'lossy' );
@@ -141,29 +150,29 @@ class TextContent extends AbstractContent {
 	 * Returns a Content object with pre-save transformations applied.
 	 * This implementation just trims trailing whitespace.
 	 *
-	 * @param $title Title
-	 * @param $user User
-	 * @param $popts ParserOptions
+	 * @param Title $title
+	 * @param User $user
+	 * @param ParserOptions $popts
+	 *
 	 * @return Content
 	 */
 	public function preSaveTransform( Title $title, User $user, ParserOptions $popts ) {
 		$text = $this->getNativeData();
 		$pst = rtrim( $text );
 
-		return ( $text === $pst ) ? $this : new WikitextContent( $pst );
+		return ( $text === $pst ) ? $this : new static( $pst, $this->getModel() );
 	}
 
 	/**
 	 * Diff this content object with another content object.
 	 *
-	 * @since 1.21diff
+	 * @since 1.21
 	 *
-	 * @param $that Content: The other content object to compare this content
-	 * object to.
-	 * @param $lang Language: The language object to use for text segmentation.
+	 * @param Content $that The other content object to compare this content object to.
+	 * @param Language $lang The language object to use for text segmentation.
 	 *    If not given, $wgContentLang is used.
 	 *
-	 * @return DiffResult: A diff representing the changes that would have to be
+	 * @return Diff A diff representing the changes that would have to be
 	 *    made to this content object to make it equal to $that.
 	 */
 	public function diff( Content $that, Language $lang = null ) {
@@ -178,43 +187,42 @@ class TextContent extends AbstractContent {
 		}
 
 		$otext = $this->getNativeData();
-		$ntext = $this->getNativeData();
+		$ntext = $that->getNativeData();
 
 		# Note: Use native PHP diff, external engines don't give us abstract output
 		$ota = explode( "\n", $lang->segmentForDiff( $otext ) );
 		$nta = explode( "\n", $lang->segmentForDiff( $ntext ) );
 
 		$diff = new Diff( $ota, $nta );
+
 		return $diff;
 	}
 
 	/**
-	 * Returns a generic ParserOutput object, wrapping the HTML returned by
-	 * getHtml().
+	 * Fills the provided ParserOutput object with information derived from the content.
+	 * Unless $generateHtml was false, this includes an HTML representation of the content
+	 * provided by getHtml().
 	 *
-	 * @param $title Title Context title for parsing
-	 * @param int|null $revId Revision ID (for {{REVISIONID}})
-	 * @param $options ParserOptions|null Parser options
-	 * @param bool $generateHtml Whether or not to generate HTML
+	 * For content models listed in $wgTextModelsToParse, this method will call the MediaWiki
+	 * wikitext parser on the text to extract any (wikitext) links, magic words, etc.
 	 *
-	 * @return ParserOutput representing the HTML form of the text
+	 * Subclasses may override this to provide custom content processing.
+	 * For custom HTML generation alone, it is sufficient to override getHtml().
+	 *
+	 * @param Title $title Context title for parsing
+	 * @param int $revId Revision ID (for {{REVISIONID}})
+	 * @param ParserOptions $options Parser options
+	 * @param bool $generateHtml Whether or not to generate HTML
+	 * @param ParserOutput $output The output object to fill (reference).
 	 */
-	public function getParserOutput( Title $title,
-		$revId = null,
-		ParserOptions $options = null, $generateHtml = true
+	protected function fillParserOutput( Title $title, $revId,
+		ParserOptions $options, $generateHtml, ParserOutput &$output
 	) {
 		global $wgParser, $wgTextModelsToParse;
 
-		if ( !$options ) {
-			//NOTE: use canonical options per default to produce cacheable output
-			$options = $this->getContentHandler()->makeParserOptions( 'canonical' );
-		}
-
 		if ( in_array( $this->getModel(), $wgTextModelsToParse ) ) {
-			// parse just to get links etc into the database
-			$po = $wgParser->parse( $this->getNativeData(), $title, $options, true, true, $revId );
-		} else {
-			$po = new ParserOutput();
+			// parse just to get links etc into the database, HTML is replaced below.
+			$output = $wgParser->parse( $this->getNativeData(), $title, $options, true, true, $revId );
 		}
 
 		if ( $generateHtml ) {
@@ -223,18 +231,19 @@ class TextContent extends AbstractContent {
 			$html = '';
 		}
 
-		$po->setText( $html );
-		return $po;
+		$output->setText( $html );
 	}
 
 	/**
 	 * Generates an HTML version of the content, for display. Used by
-	 * getParserOutput() to construct a ParserOutput object.
+	 * fillParserOutput() to provide HTML for the ParserOutput object.
+	 *
+	 * Subclasses may override this to provide a custom HTML rendering.
+	 * If further information is to be derived from the content (such as
+	 * categories), the fillParserOutput() method can be overridden instead.
 	 *
-	 * This default implementation just calls getHighlightHtml(). Content
-	 * models that have another mapping to HTML (as is the case for markup
-	 * languages like wikitext) should override this method to generate the
-	 * appropriate HTML.
+	 * For backwards-compatibility, this default implementation just calls
+	 * getHighlightHtml().
 	 *
 	 * @return string An HTML representation of the content
 	 */
@@ -243,28 +252,37 @@ class TextContent extends AbstractContent {
 	}
 
 	/**
-	 * Generates a syntax-highlighted version of the content, as HTML.
-	 * Used by the default implementation of getHtml().
+	 * Generates an HTML version of the content, for display.
+	 *
+	 * This default implementation returns an HTML-escaped version
+	 * of the raw text content.
+	 *
+	 * @note The functionality of this method should really be implemented
+	 * in getHtml(), and subclasses should override getHtml() if needed.
+	 * getHighlightHtml() is kept around for backward compatibility with
+	 * extensions that already override it.
+	 *
+	 * @deprecated since 1.24. Use getHtml() instead. In particular, subclasses overriding
+	 *     getHighlightHtml() should override getHtml() instead.
 	 *
-	 * @return string an HTML representation of the content's markup
+	 * @return string An HTML representation of the content
 	 */
 	protected function getHighlightHtml() {
-		# TODO: make Highlighter interface, use highlighter here, if available
 		return htmlspecialchars( $this->getNativeData() );
 	}
 
 	/**
-	 * @see Content::convert()
-	 *
 	 * This implementation provides lossless conversion between content models based
 	 * on TextContent.
 	 *
-	 * @param string  $toModel the desired content model, use the CONTENT_MODEL_XXX flags.
-	 * @param string  $lossy flag, set to "lossy" to allow lossy conversion. If lossy conversion is
-	 * not allowed, full round-trip conversion is expected to work without losing information.
+	 * @param string $toModel The desired content model, use the CONTENT_MODEL_XXX flags.
+	 * @param string $lossy Flag, set to "lossy" to allow lossy conversion. If lossy conversion is not
+	 *     allowed, full round-trip conversion is expected to work without losing information.
 	 *
-	 * @return Content|bool A content object with the content model $toModel, or false if
-	 * that conversion is not supported.
+	 * @return Content|bool A content object with the content model $toModel, or false if that
+	 *     conversion is not supported.
+	 *
+	 * @see Content::convert()
 	 */
 	public function convert( $toModel, $lossy = '' ) {
 		$converted = parent::convert( $toModel, $lossy );
@@ -276,11 +294,12 @@ class TextContent extends AbstractContent {
 		$toHandler = ContentHandler::getForModelID( $toModel );
 
 		if ( $toHandler instanceof TextContentHandler ) {
-			//NOTE: ignore content serialization format - it's just text anyway.
+			// NOTE: ignore content serialization format - it's just text anyway.
 			$text = $this->getNativeData();
 			$converted = $toHandler->unserializeContent( $text );
 		}
 
 		return $converted;
 	}
+
 }
diff --git a/includes/content/TextContentHandler.php b/includes/content/TextContentHandler.php
index e7f41e18..ffe1acbd 100644
--- a/includes/content/TextContentHandler.php
+++ b/includes/content/TextContentHandler.php
@@ -30,19 +30,24 @@
  */
 class TextContentHandler extends ContentHandler {
 
-	public function __construct( $modelId = CONTENT_MODEL_TEXT, $formats = array( CONTENT_FORMAT_TEXT ) ) {
+	// @codingStandardsIgnoreStart bug 57585
+	public function __construct( $modelId = CONTENT_MODEL_TEXT,
+		$formats = array( CONTENT_FORMAT_TEXT ) ) {
 		parent::__construct( $modelId, $formats );
 	}
+	// @codingStandardsIgnoreEnd
 
 	/**
 	 * Returns the content's text as-is.
 	 *
-	 * @param $content Content
-	 * @param $format string|null
+	 * @param Content $content
+	 * @param string $format The serialization format to check
+	 *
 	 * @return mixed
 	 */
 	public function serializeContent( Content $content, $format = null ) {
 		$this->checkFormat( $format );
+
 		return $content->getNativeData();
 	}
 
@@ -55,11 +60,11 @@ class TextContentHandler extends ContentHandler {
 	 *
 	 * This text-based implementation uses wfMerge().
 	 *
-	 * @param $oldContent Content|string  String
-	 * @param $myContent Content|string   String
-	 * @param $yourContent Content|string String
+	 * @param Content $oldContent The page's previous content.
+	 * @param Content $myContent One of the page's conflicting contents.
+	 * @param Content $yourContent One of the page's conflicting contents.
 	 *
-	 * @return Content|Bool
+	 * @return Content|bool
 	 */
 	public function merge3( Content $oldContent, Content $myContent, Content $yourContent ) {
 		$this->checkModelID( $oldContent->getModel() );
@@ -83,23 +88,38 @@ class TextContentHandler extends ContentHandler {
 		}
 
 		$mergedContent = $this->unserializeContent( $result, $format );
+
 		return $mergedContent;
 	}
 
 	/**
+	 * Returns the name of the associated Content class, to
+	 * be used when creating new objects. Override expected
+	 * by subclasses.
+	 *
+	 * @since 1.24
+	 *
+	 * @return string
+	 */
+	protected function getContentClass() {
+		return 'TextContent';
+	}
+
+	/**
 	 * Unserializes a Content object of the type supported by this ContentHandler.
 	 *
 	 * @since 1.21
 	 *
-	 * @param $text   string serialized form of the content
-	 * @param $format null|String the format used for serialization
+	 * @param string $text Serialized form of the content
+	 * @param string $format The format used for serialization
 	 *
-	 * @return Content the TextContent object wrapping $text
+	 * @return Content The TextContent object wrapping $text
 	 */
 	public function unserializeContent( $text, $format = null ) {
 		$this->checkFormat( $format );
 
-		return new TextContent( $text );
+		$class = $this->getContentClass();
+		return new $class( $text );
 	}
 
 	/**
@@ -107,9 +127,11 @@ class TextContentHandler extends ContentHandler {
 	 *
 	 * @since 1.21
 	 *
-	 * @return Content
+	 * @return Content A new TextContent object with empty text.
 	 */
 	public function makeEmptyContent() {
-		return new TextContent( '' );
+		$class = $this->getContentClass();
+		return new $class( '' );
 	}
+
 }
diff --git a/includes/content/WikitextContent.php b/includes/content/WikitextContent.php
index 26337db9..9a8ab3a6 100644
--- a/includes/content/WikitextContent.php
+++ b/includes/content/WikitextContent.php
@@ -31,31 +31,43 @@
  * @ingroup Content
  */
 class WikitextContent extends TextContent {
+	private $redirectTargetAndText = null;
 
 	public function __construct( $text ) {
 		parent::__construct( $text, CONTENT_MODEL_WIKITEXT );
 	}
 
 	/**
+	 * @param string|number $sectionId
+	 *
+	 * @return Content|bool|null
+	 *
 	 * @see Content::getSection()
 	 */
-	public function getSection( $section ) {
+	public function getSection( $sectionId ) {
 		global $wgParser;
 
 		$text = $this->getNativeData();
-		$sect = $wgParser->getSection( $text, $section, false );
+		$sect = $wgParser->getSection( $text, $sectionId, false );
 
 		if ( $sect === false ) {
 			return false;
 		} else {
-			return new WikitextContent( $sect );
+			return new static( $sect );
 		}
 	}
 
 	/**
+	 * @param string|number|null|bool $sectionId
+	 * @param Content $with
+	 * @param string $sectionTitle
+	 *
+	 * @throws MWException
+	 * @return Content
+	 *
 	 * @see Content::replaceSection()
 	 */
-	public function replaceSection( $section, Content $with, $sectionTitle = '' ) {
+	public function replaceSection( $sectionId, Content $with, $sectionTitle = '' ) {
 		wfProfileIn( __METHOD__ );
 
 		$myModelId = $this->getModel();
@@ -71,13 +83,16 @@ class WikitextContent extends TextContent {
 		$oldtext = $this->getNativeData();
 		$text = $with->getNativeData();
 
-		if ( $section === '' ) {
+		if ( strval( $sectionId ) === '' ) {
 			wfProfileOut( __METHOD__ );
+
 			return $with; # XXX: copy first?
-		} if ( $section == 'new' ) {
+		}
+
+		if ( $sectionId === 'new' ) {
 			# Inserting a new section
 			$subject = $sectionTitle ? wfMessage( 'newsectionheaderdefaultlevel' )
-				->rawParams( $sectionTitle )->inContentLanguage()->text() . "\n\n" : '';
+					->rawParams( $sectionTitle )->inContentLanguage()->text() . "\n\n" : '';
 			if ( wfRunHooks( 'PlaceNewSection', array( $this, $oldtext, $subject, &$text ) ) ) {
 				$text = strlen( trim( $oldtext ) ) > 0
 					? "{$oldtext}\n\n{$subject}{$text}"
@@ -87,12 +102,13 @@ class WikitextContent extends TextContent {
 			# Replacing an existing section; roll out the big guns
 			global $wgParser;
 
-			$text = $wgParser->replaceSection( $oldtext, $section, $text );
+			$text = $wgParser->replaceSection( $oldtext, $sectionId, $text );
 		}
 
-		$newContent = new WikitextContent( $text );
+		$newContent = new static( $text );
 
 		wfProfileOut( __METHOD__ );
+
 		return $newContent;
 	}
 
@@ -100,7 +116,8 @@ class WikitextContent extends TextContent {
 	 * Returns a new WikitextContent object with the given section heading
 	 * prepended.
 	 *
-	 * @param $header string
+	 * @param string $header
+	 *
 	 * @return Content
 	 */
 	public function addSectionHeader( $header ) {
@@ -109,16 +126,17 @@ class WikitextContent extends TextContent {
 		$text .= "\n\n";
 		$text .= $this->getNativeData();
 
-		return new WikitextContent( $text );
+		return new static( $text );
 	}
 
 	/**
 	 * Returns a Content object with pre-save transformations applied using
 	 * Parser::preSaveTransform().
 	 *
-	 * @param $title Title
-	 * @param $user User
-	 * @param $popts ParserOptions
+	 * @param Title $title
+	 * @param User $user
+	 * @param ParserOptions $popts
+	 *
 	 * @return Content
 	 */
 	public function preSaveTransform( Title $title, User $user, ParserOptions $popts ) {
@@ -128,50 +146,58 @@ class WikitextContent extends TextContent {
 		$pst = $wgParser->preSaveTransform( $text, $title, $user, $popts );
 		rtrim( $pst );
 
-		return ( $text === $pst ) ? $this : new WikitextContent( $pst );
+		return ( $text === $pst ) ? $this : new static( $pst );
 	}
 
 	/**
 	 * Returns a Content object with preload transformations applied (or this
 	 * object if no transformations apply).
 	 *
-	 * @param $title Title
-	 * @param $popts ParserOptions
+	 * @param Title $title
+	 * @param ParserOptions $popts
+	 * @param array $params
+	 *
 	 * @return Content
 	 */
-	public function preloadTransform( Title $title, ParserOptions $popts ) {
+	public function preloadTransform( Title $title, ParserOptions $popts, $params = array() ) {
 		global $wgParser;
 
 		$text = $this->getNativeData();
-		$plt = $wgParser->getPreloadText( $text, $title, $popts );
+		$plt = $wgParser->getPreloadText( $text, $title, $popts, $params );
 
-		return new WikitextContent( $plt );
+		return new static( $plt );
 	}
 
 	/**
-	 * Implement redirect extraction for wikitext.
+	 * Extract the redirect target and the remaining text on the page.
 	 *
-	 * @return null|Title
+	 * @note migrated here from Title::newFromRedirectInternal()
 	 *
-	 * @note: migrated here from Title::newFromRedirectInternal()
+	 * @since 1.23
 	 *
-	 * @see Content::getRedirectTarget
-	 * @see AbstractContent::getRedirectTarget
+	 * @return array List of two elements: Title|null and string.
 	 */
-	public function getRedirectTarget() {
+	protected function getRedirectTargetAndText() {
 		global $wgMaxRedirects;
+
+		if ( $this->redirectTargetAndText !== null ) {
+			return $this->redirectTargetAndText;
+		}
+
 		if ( $wgMaxRedirects < 1 ) {
 			// redirects are disabled, so quit early
-			return null;
+			$this->redirectTargetAndText = array( null, $this->getNativeData() );
+			return $this->redirectTargetAndText;
 		}
+
 		$redir = MagicWord::get( 'redirect' );
-		$text = trim( $this->getNativeData() );
+		$text = ltrim( $this->getNativeData() );
 		if ( $redir->matchStartAndRemove( $text ) ) {
 			// Extract the first link and see if it's usable
 			// Ensure that it really does come directly after #REDIRECT
 			// Some older redirects included a colon, so don't freak about that!
 			$m = array();
-			if ( preg_match( '!^\s*:?\s*\[{2}(.*?)(?:\|.*?)?\]{2}!', $text, $m ) ) {
+			if ( preg_match( '!^\s*:?\s*\[{2}(.*?)(?:\|.*?)?\]{2}\s*!', $text, $m ) ) {
 				// Strip preceding colon used to "escape" categories, etc.
 				// and URL-decode links
 				if ( strpos( $m[1], '%' ) !== false ) {
@@ -181,17 +207,33 @@ class WikitextContent extends TextContent {
 				$title = Title::newFromText( $m[1] );
 				// If the title is a redirect to bad special pages or is invalid, return null
 				if ( !$title instanceof Title || !$title->isValidRedirectTarget() ) {
-					return null;
+					$this->redirectTargetAndText = array( null, $this->getNativeData() );
+					return $this->redirectTargetAndText;
 				}
-				return $title;
+
+				$this->redirectTargetAndText = array( $title, substr( $text, strlen( $m[0] ) ) );
+				return $this->redirectTargetAndText;
 			}
 		}
-		return null;
+
+		$this->redirectTargetAndText = array( null, $this->getNativeData() );
+		return $this->redirectTargetAndText;
 	}
 
 	/**
-	 * @see   Content::updateRedirect()
+	 * Implement redirect extraction for wikitext.
 	 *
+	 * @return Title|null
+	 *
+	 * @see Content::getRedirectTarget
+	 */
+	public function getRedirectTarget() {
+		list( $title, ) = $this->getRedirectTargetAndText();
+
+		return $title;
+	}
+
+	/**
 	 * This implementation replaces the first link on the page with the given new target
 	 * if this Content object is a redirect. Otherwise, this method returns $this.
 	 *
@@ -199,7 +241,9 @@ class WikitextContent extends TextContent {
 	 *
 	 * @param Title $target
 	 *
-	 * @return Content a new Content object with the updated redirect (or $this if this Content object isn't a redirect)
+	 * @return Content
+	 *
+	 * @see Content::updateRedirect()
 	 */
 	public function updateRedirect( Title $target ) {
 		if ( !$this->isRedirect() ) {
@@ -213,21 +257,19 @@ class WikitextContent extends TextContent {
 			'[[' . $target->getFullText() . ']]',
 			$this->getNativeData(), 1 );
 
-		return new WikitextContent( $newText );
+		return new static( $newText );
 	}
 
 	/**
 	 * Returns true if this content is not a redirect, and this content's text
 	 * is countable according to the criteria defined by $wgArticleCountMethod.
 	 *
-	 * @param bool $hasLinks  if it is known whether this content contains
+	 * @param bool $hasLinks If it is known whether this content contains
 	 *    links, provide this information here, to avoid redundant parsing to
 	 *    find out (default: null).
-	 * @param $title Title: (default: null)
-	 *
-	 * @internal param \IContextSource $context context for parsing if necessary
+	 * @param Title $title Optional title, defaults to the title from the current main request.
 	 *
-	 * @return bool True if the content is countable
+	 * @return bool
 	 */
 	public function isCountable( $hasLinks = null, Title $title = null ) {
 		global $wgArticleCountMethod;
@@ -261,6 +303,10 @@ class WikitextContent extends TextContent {
 		return false;
 	}
 
+	/**
+	 * @param int $maxlength
+	 * @return string
+	 */
 	public function getTextForSummary( $maxlength = 250 ) {
 		$truncatedtext = parent::getTextForSummary( $maxlength );
 
@@ -276,31 +322,39 @@ class WikitextContent extends TextContent {
 	 * Returns a ParserOutput object resulting from parsing the content's text
 	 * using $wgParser.
 	 *
-	 * @since    1.21
-	 *
-	 * @param $title Title
+	 * @param Title $title
 	 * @param int $revId Revision to pass to the parser (default: null)
-	 * @param $options ParserOptions (default: null)
-	 * @param bool $generateHtml (default: false)
-	 *
-	 * @internal param \IContextSource|null $context
-	 * @return ParserOutput representing the HTML form of the text
+	 * @param ParserOptions $options (default: null)
+	 * @param bool $generateHtml (default: true)
+	 * @param ParserOutput &$output ParserOutput representing the HTML form of the text,
+	 *           may be manipulated or replaced.
 	 */
-	public function getParserOutput( Title $title,
-		$revId = null,
-		ParserOptions $options = null, $generateHtml = true
+	protected function fillParserOutput( Title $title, $revId,
+			ParserOptions $options, $generateHtml, ParserOutput &$output
 	) {
 		global $wgParser;
 
-		if ( !$options ) {
-			//NOTE: use canonical options per default to produce cacheable output
-			$options = $this->getContentHandler()->makeParserOptions( 'canonical' );
+		list( $redir, $text ) = $this->getRedirectTargetAndText();
+		$output = $wgParser->parse( $text, $title, $options, true, true, $revId );
+
+		// Add redirect indicator at the top
+		if ( $redir ) {
+			// Make sure to include the redirect link in pagelinks
+			$output->addLink( $redir );
+			if ( $generateHtml ) {
+				$chain = $this->getRedirectChain();
+				$output->setText(
+					Article::getRedirectHeaderHtml( $title->getPageLanguage(), $chain, false ) .
+					$output->getText()
+				);
+				$output->addModuleStyles( 'mediawiki.action.view.redirectPage' );
+			}
 		}
-
-		$po = $wgParser->parse( $this->getNativeData(), $title, $options, true, true, $revId );
-		return $po;
 	}
 
+	/**
+	 * @throws MWException
+	 */
 	protected function getHtml() {
 		throw new MWException(
 			"getHtml() not implemented for wikitext. "
@@ -309,15 +363,16 @@ class WikitextContent extends TextContent {
 	}
 
 	/**
-	 * @see  Content::matchMagicWord()
-	 *
 	 * This implementation calls $word->match() on the this TextContent object's text.
 	 *
 	 * @param MagicWord $word
 	 *
-	 * @return bool whether this Content object matches the given magic word.
+	 * @return bool
+	 *
+	 * @see Content::matchMagicWord()
 	 */
 	public function matchMagicWord( MagicWord $word ) {
 		return $word->match( $this->getNativeData() );
 	}
+
 }
diff --git a/includes/content/WikitextContentHandler.php b/includes/content/WikitextContentHandler.php
index b1b461fb..c1db1de6 100644
--- a/includes/content/WikitextContentHandler.php
+++ b/includes/content/WikitextContentHandler.php
@@ -34,30 +34,19 @@ class WikitextContentHandler extends TextContentHandler {
 		parent::__construct( $modelId, array( CONTENT_FORMAT_WIKITEXT ) );
 	}
 
-	public function unserializeContent( $text, $format = null ) {
-		$this->checkFormat( $format );
-
-		return new WikitextContent( $text );
-	}
-
-	/**
-	 * @see ContentHandler::makeEmptyContent
-	 *
-	 * @return Content
-	 */
-	public function makeEmptyContent() {
-		return new WikitextContent( '' );
+	protected function getContentClass() {
+		return 'WikitextContent';
 	}
 
 	/**
 	 * Returns a WikitextContent object representing a redirect to the given destination page.
 	 *
-	 * @see ContentHandler::makeRedirectContent
-	 *
-	 * @param Title $destination the page to redirect to.
-	 * @param string $text text to include in the redirect, if possible.
+	 * @param Title $destination The page to redirect to.
+	 * @param string $text Text to include in the redirect, if possible.
 	 *
 	 * @return Content
+	 *
+	 * @see ContentHandler::makeRedirectContent
 	 */
 	public function makeRedirectContent( Title $destination, $text = '' ) {
 		$optionalColon = '';
@@ -72,20 +61,23 @@ class WikitextContentHandler extends TextContentHandler {
 		}
 
 		$mwRedir = MagicWord::get( 'redirect' );
-		$redirectText = $mwRedir->getSynonym( 0 ) . ' [[' . $optionalColon . $destination->getFullText() . ']]';
+		$redirectText = $mwRedir->getSynonym( 0 ) .
+			' [[' . $optionalColon . $destination->getFullText() . ']]';
+
 		if ( $text != '' ) {
 			$redirectText .= "\n" . $text;
 		}
 
-		return new WikitextContent( $redirectText );
+		$class = $this->getContentClass();
+		return new $class( $redirectText );
 	}
 
 	/**
 	 * Returns true because wikitext supports redirects.
 	 *
-	 * @see ContentHandler::supportsRedirects
+	 * @return bool Always true.
 	 *
-	 * @return boolean whether redirects are supported.
+	 * @see ContentHandler::supportsRedirects
 	 */
 	public function supportsRedirects() {
 		return true;
@@ -94,7 +86,9 @@ class WikitextContentHandler extends TextContentHandler {
 	/**
 	 * Returns true because wikitext supports sections.
 	 *
-	 * @return boolean whether sections are supported.
+	 * @return bool Always true.
+	 *
+	 * @see ContentHandler::supportsSections
 	 */
 	public function supportsSections() {
 		return true;
@@ -105,9 +99,13 @@ class WikitextContentHandler extends TextContentHandler {
 	 * ParserCache mechanism.
 	 *
 	 * @since 1.21
-	 * @return bool
+	 *
+	 * @return bool Always true.
+	 *
+	 * @see ContentHandler::isParserCacheSupported
 	 */
 	public function isParserCacheSupported() {
 		return true;
 	}
+
 }