Function parseARule

lib/css/syntax.js:2118–2139

(input, pos, comment)

 * @returns {Rule | undefined} the parsed rule
 */
const parseARule = (input, pos, comment) => {
	// 1. Normalize input, and set input to the result.
	const ts = normalizeIntoTokenStream(input, pos, comment);
	useObjectBackend(ts.locConverter);
	// 2. Discard whitespace from input.
	while (ts.next().type === TT_WHITESPACE) ts.discard();
	// 3. If the next token from input is an <EOF-token>, return a syntax error.
	// Otherwise, if the next token from input is an <at-keyword-token>, consume an at-rule from input, and let rule be the return value.
	// Otherwise, consume a qualified rule from input and let rule be the return value.
	// If nothing or an invalid rule error was returned, return a syntax error.
	const head = ts.next();
	if (head.type === TT_EOF) return undefined;
	const rule =
		head.type === TT_AT_KEYWORD
			? consumeAnAtRule(ts)
			: consumeAQualifiedRule(ts);
	if (!rule) return undefined;
	// 4. Discard whitespace from input.
	while (ts.next().type === TT_WHITESPACE) ts.discard();
	// 5. If the next token from input is an <EOF-token>, return rule. Otherwise, return a syntax error.
	return ts.next().type === TT_EOF ? rule : undefined;
};

/**
 * Parse a declaration, CSS Syntax Level 3