/**
 * @license
 * Copyright 2024 Google LLC
 * SPDX-License-Identifier: Apache-2.0
 */
import { LitElement } from 'lit';
import { WithElementInternals } from './element-internals.js';
import { MixinBase, MixinReturn } from './mixin.js';
/**
 * A unique symbol used to check if an element's `CustomStateSet` has a state.
 *
 * Provides compatibility with legacy dashed identifier syntax (`:--state`) used
 * by the element-internals-polyfill for Chrome extension support.
 *
 * @example
 * ```ts
 * const baseClass = mixinCustomStateSet(mixinElementInternals(LitElement));
 *
 * class MyElement extends baseClass {
 *   get checked() {
 *     return this[hasState]('checked');
 *   }
 *   set checked(value: boolean) {
 *     this[toggleState]('checked', value);
 *   }
 * }
 * ```
 */
export declare const hasState: unique symbol;
/**
 * A unique symbol used to add or delete a state from an element's
 * `CustomStateSet`.
 *
 * Provides compatibility with legacy dashed identifier syntax (`:--state`) used
 * by the element-internals-polyfill for Chrome extension support.
 *
 * @example
 * ```ts
 * const baseClass = mixinCustomStateSet(mixinElementInternals(LitElement));
 *
 * class MyElement extends baseClass {
 *   get checked() {
 *     return this[hasState]('checked');
 *   }
 *   set checked(value: boolean) {
 *     this[toggleState]('checked', value);
 *   }
 * }
 * ```
 */
export declare const toggleState: unique symbol;
/**
 * An instance with `[hasState]()` and `[toggleState]()` symbol functions that
 * provide compatibility with `CustomStateSet` legacy dashed identifier syntax,
 * used by the element-internals-polyfill and needed for Chrome extension
 * compatibility.
 */
export interface WithCustomStateSet {
    /**
     * Checks if the state is active, returning true if the element matches
     * `:state(customstate)`.
     *
     * @param customState the `CustomStateSet` state to check. Do not use the
     *     `--customstate` dashed identifier syntax.
     * @return true if the custom state is active, or false if not.
     */
    [hasState](customState: string): boolean;
    /**
     * Toggles the state to be active or inactive based on the provided value.
     * When active, the element matches `:state(customstate)`.
     *
     * @param customState the `CustomStateSet` state to check. Do not use the
     *     `--customstate` dashed identifier syntax.
     * @param isActive true to add the state, or false to delete it.
     */
    [toggleState](customState: string, isActive: boolean): void;
}
/**
 * Mixes in compatibility functions for access to an element's `CustomStateSet`.
 *
 * Use this mixin's `[hasState]()` and `[toggleState]()` symbol functions for
 * compatibility with `CustomStateSet` legacy dashed identifier syntax.
 *
 * https://developer.mozilla.org/en-US/docs/Web/API/CustomStateSet#compatibility_with_dashed-ident_syntax.
 *
 * The dashed identifier syntax is needed for element-internals-polyfill, a
 * requirement for Chome extension compatibility.
 *
 * @example
 * ```ts
 * const baseClass = mixinCustomStateSet(mixinElementInternals(LitElement));
 *
 * class MyElement extends baseClass {
 *   get checked() {
 *     return this[hasState]('checked');
 *   }
 *   set checked(value: boolean) {
 *     this[toggleState]('checked', value);
 *   }
 * }
 * ```
 *
 * @param base The class to mix functionality into.
 * @return The provided class with `[hasState]()` and `[toggleState]()`
 *     functions mixed in.
 */
export declare function mixinCustomStateSet<T extends MixinBase<LitElement & WithElementInternals>>(base: T): MixinReturn<T, WithCustomStateSet>;