import { AbortOptions, MaybePromise } from '@mithic/commons';
import { Queue } from './queue.js';
import { Stack } from './stack.js';
/** A double-ended queue. */
export interface Deque<T> extends Queue<T>, Stack<T> {
    /** Adds an element to the front of this {@link Deque}. */
    unshift(item: T, options?: AbortOptions): MaybePromise<unknown>;
}
/** A {@link Deque} that supports peeking the front/back elements. */
export interface PeekableDeque<T> extends Deque<T> {
    front(options?: AbortOptions): MaybePromise<T | undefined>;
    back(options?: AbortOptions): MaybePromise<T | undefined>;
}
/** A {@link Deque} with synchronous operations. */
export interface SyncDeque<T> extends Deque<T> {
    front?(): T | undefined;
    back?(): T | undefined;
    push(item: T): void;
    pop(): T | undefined;
    unshift(item: T): void;
    shift(): T | undefined;
}
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