public function format(CellInterface $cell) : string
{
if (!$cell->value() instanceof \DateTimeInterface) {
throw new InvalidArgumentException();
}
return $cell->value()->format($this->format);
}
private function position(CellInterface $cell) : self
{
$column = $cell->position()->column();
$row = $cell->position()->row();
$columns = $this->columns;
$rows = $this->rows;
if (!$columns->contains($column)) {
$columns = $columns->put($column, new Column($column, new Map('scalar', CellInterface::class)));
}
if (!$rows->contains($row)) {
$rows = $rows->put($row, new Row($row, new Map('scalar', CellInterface::class)));
}
$columns = $columns->put($column, new Column($column, $columns->get($column)->cells()->put($row, $cell)));
$rows = $rows->put($row, new Row($row, $rows->get($row)->cells()->put($column, $cell)));
$sheet = new self($this->name);
$sheet->rows = $rows;
$sheet->columns = $columns;
return $sheet;
}