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diff --git a/www/wiki/includes/libs/http/HttpAcceptParser.php b/www/wiki/includes/libs/http/HttpAcceptParser.php
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+++ b/www/wiki/includes/libs/http/HttpAcceptParser.php
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+<?php
+
+/**
+ * Utility for parsing a HTTP Accept header value into a weight map. May also be used with
+ * other, similar headers like Accept-Language, Accept-Encoding, etc.
+ *
+ * @license GPL-2.0-or-later
+ * @author Daniel Kinzler
+ */
+
+namespace Wikimedia\Http;
+
+class HttpAcceptParser {
+
+	/**
+	 * Parses an HTTP header into a weight map, that is an associative array
+	 * mapping values to their respective weights. Any header name preceding
+	 * weight spec is ignored for convenience.
+	 *
+	 * This implementation is partially based on the code at
+	 * http://www.thefutureoftheweb.com/blog/use-accept-language-header
+	 *
+	 * Note that type parameters and accept extension like the "level" parameter
+	 * are not supported, weights are derived from "q" values only.
+	 *
+	 * @todo: If additional type parameters are present, ignore them cleanly.
+	 *        At present, they often confuse the result.
+	 *
+	 * See HTTP/1.1 section 14 for details.
+	 *
+	 * @param string $rawHeader
+	 *
+	 * @return array
+	 */
+	public function parseWeights( $rawHeader ) {
+		//FIXME: The code below was copied and adapted from WebRequest::getAcceptLang.
+		//       Move this utility class into core for reuse!
+
+		// first, strip header name
+		$rawHeader = preg_replace( '/^[-\w]+:\s*/', '', $rawHeader );
+
+		// Return values in lower case
+		$rawHeader = strtolower( $rawHeader );
+
+		// Break up string into pieces (values and q factors)
+		$value_parse = null;
+		preg_match_all( '@([a-z\d*]+([-+/.][a-z\d*]+)*)\s*(;\s*q\s*=\s*(1(\.0{0,3})?|0(\.\d{0,3})?)?)?@',
+			$rawHeader, $value_parse );
+
+		if ( !count( $value_parse[1] ) ) {
+			return [];
+		}
+
+		$values = $value_parse[1];
+		$qvalues = $value_parse[4];
+		$indices = range( 0, count( $value_parse[1] ) - 1 );
+
+		// Set default q factor to 1
+		foreach ( $indices as $index ) {
+			if ( $qvalues[$index] === '' ) {
+				$qvalues[$index] = 1;
+			} elseif ( $qvalues[$index] == 0 ) {
+				unset( $values[$index], $qvalues[$index], $indices[$index] );
+			} else {
+				$qvalues[$index] = (float)$qvalues[$index];
+			}
+		}
+
+		// Sort list. First by $qvalues, then by order. Reorder $values the same way
+		array_multisort( $qvalues, SORT_DESC, SORT_NUMERIC, $indices, $values );
+
+		// Create a list like "en" => 0.8
+		$weights = array_combine( $values, $qvalues );
+
+		return $weights;
+	}
+
+}