src/Peach/Http/Util.php
private static function parseQualityValue($value)
    {
        $values  = preg_split("/\\s*,\\s*/", $value);
        $matched = array();
        $qvList  = array();
        foreach ($values as $item) {
            if (preg_match("/\\A([^;]+)\\s*;\\s*(.+)\\z/", $item, $matched)) {
                $key    = $matched[1];
                $qvalue = self::parseQvalue($matched[2]);
            } else {
                $key    = $item;
                $qvalue = 1.0;
            }
            $qvList[$key] = $qvalue;
        }
        return $qvList;
    }
private static function parseQualityValue($value)
    {
        $values  = preg_split("/\\s*,\\s*/", $value);
        $matched = array();
        $qvList  = array();
        foreach ($values as $item) {
            if (preg_match("/\\A([^;]+)\\s*;\\s*(.+)\\z/", $item, $matched)) {
                $key    = $matched[1];
                $qvalue = self::parseQvalue($matched[2]);
            } else {
                $key    = $item;
                $qvalue = 1.0;
            }
            $qvList[$key] = $qvalue;
        }
        return $qvList;
    }
qualitiy value を配列に変換します.
引数を "ja,en-us;q=0.8,en;q=0.6" とした場合, 返り値は以下の配列になります.
<pre>
array("ja" => 1.0, "en-us" => 0.8, "en" => 0.6)
</pre>

@param  string $value
@return array