import type { AbortSignalArgs } from './types.js';
/**
 * The options passed to {@link Condition} when adding a listener.
 */
export type ConditionOptions = AbortSignalArgs & {
    /**
     * Whether to call the listener for both state begin and state end, as opposed to just begin.
     *
     * @default false
     */
    both?: boolean;
};
/**
 * A listener added to {@link Condition}.
 */
export type ConditionListener<T> = (state: T) => any;
/**
 * Controls a value which fires begin/end listeners on its state change.
 */
export declare class Condition<T> {
    private listeners;
    private signal;
    private _state;
    constructor(defaultValue: T, options?: AbortSignalArgs);
    get state(): T;
    set state(v: T);
    /**
     * Does this {@link Condition} currently have any listeners.
     */
    observed(): boolean;
    /**
     * For subclasses to override. The actions to take when the first listener is added.
     */
    protected setup(): void;
    /**
     * For subclasses to override. The actions to take when the last listener is removed, or this
     * {@link Condition} is aborted.
     */
    protected teardown(): void;
    /**
     * Adds a listener to this {@link Condition}.
     */
    addListener(fn: ConditionListener<T>, options?: ConditionOptions): boolean;
    /**
     * Removes a listener from this {@link Condition}.
     */
    removeListener(fn: ConditionListener<T>): boolean;
}