src/Http/Formatting/RequestHeaderParser.php
public function parseAcceptLanguageHeader(HttpHeaders $headers): array
    {
        $headerValues = [];

        if (!$headers->tryGet('Accept-Language', $headerValues)) {
            return [];
        }

        $parsedHeaderValues = [];
        $numHeaderValues = count($headerValues);

        for ($i = 0;$i < $numHeaderValues;$i++) {
            $parsedHeaderParameters = $this->parseParameters($headers, 'Accept-Language', $i);
            // The first value should always be the language
            $language = $parsedHeaderParameters->getKeys()[0];
            $parsedHeaderValues[] = new AcceptLanguageHeaderValue($language, $parsedHeaderParameters);
        }

        return $parsedHeaderValues;
    }
public function parseAcceptLanguageHeader(HttpHeaders $headers): array
    {
        $headerValues = [];

        if (!$headers->tryGet('Accept-Language', $headerValues)) {
            return [];
        }

        $parsedHeaderValues = [];
        $numHeaderValues = count($headerValues);

        for ($i = 0;$i < $numHeaderValues;$i++) {
            $parsedHeaderParameters = $this->parseParameters($headers, 'Accept-Language', $i);
            // The first value should always be the language
            $language = $parsedHeaderParameters->getKeys()[0];
            $parsedHeaderValues[] = new AcceptLanguageHeaderValue($language, $parsedHeaderParameters);
        }

        return $parsedHeaderValues;
    }
Parses the Accept-Language header

@param HttpHeaders $headers The request headers to parse
@return AcceptLanguageHeaderValue[] The list of language header values
@throws InvalidArgumentException Thrown if the headers were incorrectly formatted