Function parseImportPrelude

lib/css/CssParser.js:703–764

(prelude)

 * @returns {ImportPrelude} the recognized prefix parts (any may be undefined)
 */
const parseImportPrelude = (prelude) => {
	/** @type {AstNode | undefined} */
	let urlNode;
	/** @type {AstNode | undefined} */
	let layerNode;
	/** @type {FunctionNode | undefined} */
	let supportsNode;

	for (const cv of prelude) {
		const t = A.type(cv);
		if (t === NodeType.Whitespace) continue;

		if (!urlNode) {
			if (t === NodeType.Url || t === NodeType.String) {
				urlNode = cv;
				continue;
			}
			if (
				t === NodeType.Function &&
				equalsLowerCase(A.unescapedName(cv), "url")
			) {
				urlNode = cv;
				continue;
			}
			if (t === NodeType.Ident) {
				// CSS Modules: bare ident is a `@value` reference.
				urlNode = cv;
				continue;
			}
			break;
		}

		if (!layerNode && !supportsNode) {
			if (t === NodeType.Ident) {
				if (equalsLowerCase(A.unescaped(cv), "layer")) {
					layerNode = cv;
					continue;
				}
			} else if (
				t === NodeType.Function &&
				equalsLowerCase(A.unescapedName(cv), "layer")
			) {
				layerNode = cv;
				continue;
			}
		}

		if (
			!supportsNode &&
			t === NodeType.Function &&
			equalsLowerCase(A.unescapedName(cv), "supports")
		) {
			supportsNode = /** @type {FunctionNode} */ (cv);
			continue;
		}

		// First media-query token — stop scanning for the prefix.
		break;