apply_combinator() — svelte Function Reference

Source Code

packages/svelte/src/compiler/phases/2-analyze/css/css-prune.js lines 223–285

function apply_combinator(relative_selector, rest_selectors, rule, node, direction) {
	const combinator =
		direction == FORWARD ? rest_selectors[0]?.combinator : relative_selector.combinator;
	if (!combinator) return true;

	switch (combinator.name) {
		case ' ':
		case '>': {
			const is_adjacent = combinator.name === '>';
			const parents =
				direction === FORWARD
					? get_descendant_elements(node, is_adjacent)
					: get_ancestor_elements(node, is_adjacent);
			let parent_matched = false;

			for (const parent of parents) {
				if (apply_selector(rest_selectors, rule, parent, direction)) {
					parent_matched = true;
				}
			}

			return (
				parent_matched ||
				(direction === BACKWARD &&
					(!is_adjacent || parents.length === 0) &&
					rest_selectors.every((selector) => is_global(selector, rule)))
			);
		}

		case '+':
		case '~': {
			const siblings = get_possible_element_siblings(node, direction, combinator.name === '+');

			let sibling_matched = false;

			for (const possible_sibling of siblings.keys()) {
				if (
					possible_sibling.type === 'RenderTag' ||
					possible_sibling.type === 'SlotElement' ||
					possible_sibling.type === 'Component'
				) {
					// `{@render foo()}<p>foo</p>` with `:global(.x) + p` is a match
					if (rest_selectors.length === 1 && rest_selectors[0].metadata.is_global) {
						sibling_matched = true;
					}
				} else if (apply_selector(rest_selectors, rule, possible_sibling, direction)) {
					sibling_matched = true;
				}
			}

			return (
				sibling_matched ||
				(direction === BACKWARD &&
					get_element_parent(node) === null &&
					rest_selectors.every((selector) => is_global(selector, rule)))
			);
		}

		default:
			// TODO other combinators
			return true;
	}
}