Vendor/phpspreadsheet/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Cell/Coordinate.php
public static function getRangeBoundaries($pRange)
    {
        // Ensure $pRange is a valid range
        if (empty($pRange)) {
            $pRange = self::DEFAULT_RANGE;
        }

        // Uppercase coordinate
        $pRange = strtoupper($pRange);

        // Extract range
        if (strpos($pRange, ':') === false) {
            $rangeA = $rangeB = $pRange;
        } else {
            list($rangeA, $rangeB) = explode(':', $pRange);
        }

        return [self::coordinateFromString($rangeA), self::coordinateFromString($rangeB)];
    }
public static function getRangeBoundaries($pRange)
    {
        // Ensure $pRange is a valid range
        if (empty($pRange)) {
            $pRange = self::DEFAULT_RANGE;
        }

        // Uppercase coordinate
        $pRange = strtoupper($pRange);

        // Extract range
        if (strpos($pRange, ':') === false) {
            $rangeA = $rangeB = $pRange;
        } else {
            list($rangeA, $rangeB) = explode(':', $pRange);
        }

        return [self::coordinateFromString($rangeA), self::coordinateFromString($rangeB)];
    }
Calculate range boundaries.

@param string $pRange Cell range (e.g. A1:A1)

@return array Range coordinates [Start Cell, End Cell]
where Start Cell and End Cell are arrays [Column ID, Row Number]