import { CssList, type ListItem } from './list';
import type { Atrule, CssNode, Declaration, Rule } from './types';
export declare const walk: WalkFn;
export declare const walkSkip: symbol;
export declare const walkStop: symbol;
export declare interface WalkContext {
  root: CssNode
  stylesheet: CssNode | null
  atrule: Atrule | null
  atrulePrelude: CssNode | null
  rule: Rule | null
  selector: CssNode | null
  block: CssNode | null
  declaration: Declaration | null
  function: CssNode | null
}
/**
 * Object-form visitor. The `T extends WalkVisit` generic is inferred from
 * the literal value of `visit`, so writing
 *
 *     walk(ast, { visit: 'Rule', enter(node) { … } })
 *
 * narrows `node` to `Rule`. Without `visit`, callbacks receive the full
 * `CssNode` union as `enter`/`leave` arguments.
 */
export declare interface WalkVisitorObject<T extends WalkVisit | undefined = undefined> {
  visit?: T
  reverse?: boolean
  enter?: VisitorCallback<T extends WalkVisit ? CssNodeOfType<T> : CssNode>
  leave?: VisitorCallback<T extends WalkVisit ? CssNodeOfType<T> : CssNode>
}
/**
 * Walk every node of `root`, calling `visitor` (or visitor.enter / .leave).
 * Returns:
 *   - undefined when traversal completes,
 *   - the SKIP / STOP sentinel propagated from a visitor.
 *
 * `walk.skip` / `walk.stop` are exposed as static-symbol sentinels.
 */
export declare interface WalkFn {
  (root: CssNode, visitor: WalkVisitorFunction): symbol | undefined
  <T extends WalkVisit>(root: CssNode, visitor: WalkVisitorObject<T>): symbol | undefined
  skip: symbol
  stop: symbol
}
export type WalkVisit = CssNode['type'];
// Narrow CssNode by its `type` discriminant — used to type the
// `visit: 'Rule'` filter so consumer callbacks receive a `Rule`, not the
// full union.
export type CssNodeOfType<T extends WalkVisit> = Extract<CssNode, { type: T }>;
// eslint-disable-next-line pickier/no-unused-vars
declare type VisitorCallback<N> = (this: WalkContext, node: N, item: ListItem<CssNode> | null, list: CssList<CssNode> | null) => void | symbol;
/** Plain-function visitor — runs against every node. */
export type WalkVisitorFunction = VisitorCallback<CssNode>;
export type WalkVisitor = WalkVisitorFunction | WalkVisitorObject<WalkVisit | undefined>;