Function parseClassBasedSelector

packages/css-data/src/parse-css.ts:1011–1127

(
  selector: string
)

 * - Pure element/id selectors
 */
export const parseClassBasedSelector = (
  selector: string
): ParsedClassSelector | undefined => {
  let ast: csstree.CssNode;
  try {
    ast = csstree.parse(selector, { context: "selector" });
  } catch {
    return undefined;
  }

  if (ast.type !== "Selector") {
    return undefined;
  }

  const children = ast.children.toArray();
  if (children.length === 0) {
    return undefined;
  }

  // First node must be a ClassSelector
  if (children[0].type !== "ClassSelector") {
    return undefined;
  }

  // Split children into segments at Combinator nodes
  type Segment = {
    nodes: csstree.CssNode[];
    combinator?: "descendant" | "child";
  };
  const segments: Segment[] = [];
  let currentNodes: csstree.CssNode[] = [];

  for (const child of children) {
    if (child.type === "Combinator") {
      if (child.name === " ") {
        segments.push({ nodes: currentNodes, combinator: "descendant" });
      } else if (child.name === ">") {
        segments.push({ nodes: currentNodes, combinator: "child" });
      } else {
        // Sibling combinators (+, ~) — reject
        return undefined;
      }
      currentNodes = [];
    } else {
      currentNodes.push(child);
    }
  }
  // Push the last (target) segment
  segments.push({ nodes: currentNodes });

  // Validate all segments and extract class names
  const ancestors: Array<{
    classNames: string[];
    combinator: "descendant" | "child";
  }> = [];

  // Process ancestor segments (all except the last)
  for (let i = 0; i < segments.length - 1; i++) {