}

        return $subject;
    }

    /**
     * Replace the last occurrence of a given value in the string.
     *
     * @param  string  $search
     * @param  string  $replace
     * @param  string  $subject
     * @return string
     */
    public static function replaceLast($search, $replace, $subject)
    {
        if ($search === '') {
            return $subject;
        }

        $position = strrpos($subject, $search);

        if ($position !== false) {
            return substr_replace($subject, $replace, $position, strlen($search));
        }

        return $subject;
    }

    /**
     * Remove any occurrence of the given string in the subject.
     *
     * @param  string|array<string>  $search
     * @param  string  $subject
     * @param  bool  $caseSensitive
     * @return string
     */
    public static function remove($search, $subject, $caseSensitive = true)
    {
        $subject = $caseSensitive
                    ? str_replace($search, '', $subject)
                    : str_ireplace($search, '', $subject);

        return $subject;
    }

    /**
     * Reverse the given string.
     *
     * @param  string  $value
     * @return string
     */
    public static function reverse(string $value)
    {
        return implode(array_reverse(mb_str_split($value)));
    }

    /**
     * Begin a string with a single instance of a given value.
     *
     * @param  string  $value
     * @param  string  $prefix
     * @return string
     */
    public static function start($value, $prefix)
    {
        $quoted = preg_quote($prefix, '/');

        return $prefix.preg_replace('/^(?:'.$quoted.')+/u', '', $value);
    }

    /**
     * Convert the given string to upper-case.
     *
     * @param  string  $value
     * @return string
     */
    public static function upper($value)
    {
        return mb_strtoupper($value, 'UTF-8');
    }

    /**
     * Convert the given string to title case.
     *
     * @param  string  $value
     * @return string
     */
    public static function title($value)
    {
        return mb_convert_case($value, MB_CASE_TITLE, 'UTF-8');
    }

    /**
     * Convert the given string to title case for each word.
     *
     * @param  string  $value
     * @return string
     */
    public static function headline($value)
    {
        $parts = explode(' ', $value);

        $parts = count($parts) > 1
            ? $parts = array_map([static::class, 'title'], $parts)
            : $parts = array_map([static::class, 'title'], static::ucsplit(implode('_', $parts)));

        $collapsed = static::replace(['-', '_', ' '], '_', implode('_', $parts));

        return implode(' ', array_filter(explode('_', $collapsed)));
    }

    /**
     * Get the singular form of an English word.
     *
     * @param  string  $value
     * @return string
     */
    public static function singular($value)
    {
        return Pluralizer::singular($value);
    }

    /**
     * Generate a URL friendly "slug" from a given string.
     *
     * @param  string  $title
     * @param  string  $separator
     * @param  string|null  $language
     * @return string
     */
    public static function slug($title, $separator = '-', $language = 'en')
    {
        $title = $language ? static::ascii($title, $language) : $title;

        // Convert all dashes/underscores into separator
        $flip = $separator === '-' ? '_' : '-';

        $title = preg_replace('!['.preg_quote($flip).']+!u', $separator, $title);

        // Replace @ with the word 'at'
        $title = str_replace('@', $separator.'at'.$separator, $title);

        // Remove all characters that are not the separator, letters, numbers, or whitespace.
        $title = preg_replace('![^'.preg_quote($separator).'\pL\pN\s]+!u', '', static::lower($title));

        // Replace all separator characters and whitespace by a single separator
        $title = preg_replace('!['.preg_quote($separator).'\s]+!u', $separator, $title);

        return trim($title, $separator);
    }

    /**
     * Convert a string to snake case.
     *
     * @param  string  $value
     * @param  string  $delimiter
     * @return string
     */
    public static function snake($value, $delimiter = '_')
    {
        $key = $value;

        if (isset(static::$snakeCache[$key][$delimiter])) {
            return static::$snakeCache[$key][$delimiter];
        }

        if (! ctype_lower($value)) {
            $value = preg_replace('/\s+/u', '', ucwords($value));

            $value = static::lower(preg_replace('/(.)(?=[A-Z])/u', '$1'.$delimiter, $value));
        }

        return static::$snakeCache[$key][$delimiter] = $value;
    }

    /**
     * Determine if a given string starts with a given substring.
     *
     * @param  string  $haystack
     * @param  string|string[]  $needles
     * @return bool
     */
    public static function startsWith($haystack, $needles)
    {
        foreach ((array) $needles as $needle) {
            if ((string) $needle !== '' && strncmp($haystack, $needle, strlen($needle)) === 0) {
                return true;
            }
        }

        return false;
    }

    /**
     * Convert a value to studly caps case.
     *
     * @param  string  $value
     * @return string
     */
    public static function studly($value)
    {
        $key = $value;

        if (isset(static::$studlyCache[$key])) {
            return static::$studlyCache[$key];
        }

        $words = explode(' ', static::replace(['-', '_'], ' ', $value));

        $studlyWords = array_map(function ($word) {
            return static::ucfirst($word);
        }, $words);

        return static::$studlyCache[$key] = implode($studlyWords);
    }

    /**
     * Returns the portion of the string specified by the start and length parameters.
     *
     * @param  string  $string
     * @param  int  $start
     * @param  int|null  $length
     * @return string
     */
    public static function substr($string, $start, $length = null)
    {
        return mb_substr($string, $start, $length, 'UTF-8');
    }

    /**
     * Returns the number of substring occurrences.
     *
     * @param  string  $haystack
     * @param  string  $needle
     * @param  int  $offset
     * @param  int|null  $length
     * @return int
     */
    public static function substrCount($haystack, $needle, $offset = 0, $length = null)
    {
        if (! is_null($length)) {
            return substr_count($haystack, $needle, $offset, $length);
        } else {
            return substr_count($haystack, $needle, $offset);
        }
    }

    /**
     * Replace text within a portion of a string.
     *
     * @param  string|array  $string
     * @param  string|array  $replace
     * @param  array|int  $offset
     * @param  array|int|null  $length
     * @return string|array
     */
    public static function substrReplace($string, $replace, $offset = 0, $length = null)
    {
        if ($length === null) {
            $length = strlen($string);
        }

        return substr_replace($string, $replace, $offset, $length);
    }

    /**
     * Swap multiple keywords in a string with other keywords.
     *
     * @param  array  $map
     * @param  string  $subject
     * @return string
     */
    public static function swap(array $map, $subject)
    {
        return strtr($subject, $map);
    }

    /**
     * Make a string's first character uppercase.
     *
     * @param  string  $string
     * @return string
     */
    public static function ucfirst($string)
    {
        return static::upper(static::substr($string, 0, 1)).static::substr($string, 1);
    }

    /**
     * Split a string into pieces by uppercase characters.
     *
     * @param  string  $string
     * @return array
     */
    public static function ucsplit($string)
    {
        return preg_split('/(?=\p{Lu})/u', $string, -1, PREG_SPLIT_NO_EMPTY);
    }

    /**
     * Get the number of words a string contains.
     *
     * @param  string  $string
     * @return int
     */
    public static function wordCount($string)
    {
        return str_word_count($string);
    }

    /**
     * Generate a UUID (version 4).
     *
     * @return \Ramsey\Uuid\UuidInterface
     */
    public static function uuid()
    {
        return static::$uuidFactory
                    ? call_user_func(static::$uuidFactory)
                    : Uuid::uuid4();
    }

    /**
     * Generate a time-ordered UUID (version 4).
     *
     * @return \Ramsey\Uuid\UuidInterface
     */
    public static function orderedUuid()
    {
        if (static::$uuidFactory) {
            return call_user_func(static::$uuidFactory);
        }

        $factory = new UuidFactory;

        $factory->setRandomGenerator(new CombGenerator(
            $factory->getRandomGenerator(),
            $factory->getNumberConverter()
        ));

        $factory->setCodec(new TimestampFirstCombCodec(
            $factory->getUuidBuilder()
        ));

        return $factory->uuid4();
    }

    /**
     * Set the callable that will be used to generate UUIDs.
     *
     * @param  callable|null  $factory
     * @return void
     */
    public static function createUuidsUsing(callable $factory = null)
    {
        static::$uuidFactory = $factory;
    }

    /**
     * Indicate that UUIDs should be created normally and not using a custom factory.
     *
     * @return void
     */
    public static function createUuidsNormally()
    {
        static::$uuidFactory = null;
    }

    /**
     * Remove all strings from the casing caches.
     *
     * @return void
     */
    public static function flushCache()
    {
        static::$snakeCache = [];
        static::$camelCache = [];
        static::$studlyCache = [];
    }
}