Function createSelectorFromAst

packages/core/ui/styling/css-selector.ts:881–934

(asts: Array<CSSWhatSelector>)

}

function createSelectorFromAst(asts: Array<CSSWhatSelector>): SimpleSelector | SimpleSelectorSequence | ComplexSelector {
	let result: SimpleSelector | SimpleSelectorSequence | ComplexSelector;

	if (asts.length === 0) {
		return new InvalidSelector(new Error('Empty selector.'));
	}

	if (asts.length === 1) {
		return createSimpleSelectorFromAst(asts[0]);
	}

	const simpleSelectorSequences: Array<SimpleSelector | SimpleSelectorSequence> = [];

	let sequenceAsts: CSSWhatSelector[] = [];
	let combinatorCount: number = 0;

	for (const ast of asts) {
		const combinator = Combinator[ast.type];

		// Combinator means the end of a sequence
		if (combinator != null) {
			const selector = createSimpleSelectorSequenceFromAst(sequenceAsts);

			if (selector instanceof InvalidSelector) {
				return selector;
			}

			selector.combinator = combinator;
			simpleSelectorSequences.push(selector);

			combinatorCount++;
			// Cleanup stored selectors for the new sequence to take place
			sequenceAsts = [];
		} else {
			sequenceAsts.push(ast);
		}
	}

	if (combinatorCount > 0) {
		// Create a sequence using the remaining selectors after the last combinator
		if (sequenceAsts.length) {
			const selector = createSimpleSelectorSequenceFromAst(sequenceAsts);

			if (selector instanceof InvalidSelector) {
				return selector;
			}

			simpleSelectorSequences.push(selector);
		}
		return new ComplexSelector(simpleSelectorSequences);
	}

	return createSimpleSelectorSequenceFromAst(sequenceAsts);
}

export function createSelector(sel: string): SimpleSelector | SimpleSelectorSequence | ComplexSelector {
	try {