@use '../column/column.scss' as *;
@use '../../math/with-unit/with-unit.scss' as *;

/**
 * Generates a value or expression that allows to set a size
 * exactly equalled a given number of layout columns, plus gutter.
 *
 * @param    {string}     $expression       An expression describing the needed number of layout columns to fill: `needed-columns/total-columns`.
 * @param    {?number}    $gutter [null]    Space between columns.
 *
 * @return   {string|number}    Calc expression or exact value.
 */
@function offset($expression, $gutter: null) {
	$base: column($expression, $gutter);

	@if ($gutter) {
		@return calc(#{$base} + #{with-unit($gutter)});
	} @else {
		@return $base;
	}
}