import { ReadonlyCheckpoint, Checkpoint } from "@langchain/langgraph-checkpoint";
export declare function isBaseChannel(obj: unknown): obj is BaseChannel;
export declare abstract class BaseChannel<ValueType = unknown, UpdateType = unknown, CheckpointType = unknown> {
    ValueType: ValueType;
    UpdateType: UpdateType;
    /**
     * The name of the channel.
     */
    abstract lc_graph_name: string;
    /** @ignore */
    lg_is_channel: boolean;
    /**
     * Return a new identical channel, optionally initialized from a checkpoint.
     * Can be thought of as a "restoration" from a checkpoint which is a "snapshot" of the channel's state.
     *
     * @param {CheckpointType | undefined} checkpoint
     * @param {CheckpointType | undefined} initialValue
     * @returns {this}
     */
    abstract fromCheckpoint(checkpoint?: CheckpointType): this;
    /**
     * Update the channel's value with the given sequence of updates.
     * The order of the updates in the sequence is arbitrary.
     * This method is called by Pregel for all channels at the end of each step.
     * If there are no updates, it is called with an empty sequence.
     *
     * Raises InvalidUpdateError if the sequence of updates is invalid.
     * Returns True if the channel was updated, False otherwise.
     *
     * @throws {InvalidUpdateError} if the sequence of updates is invalid.
     * @param {Array<UpdateType>} values
     * @returns {void}
     */
    abstract update(values: UpdateType[]): boolean;
    /**
     * Return the current value of the channel.
     *
     * @throws {EmptyChannelError} if the channel is empty (never updated yet).
     * @returns {ValueType}
     */
    abstract get(): ValueType;
    /**
     * Return a string representation of the channel's current state.
     *
     * @throws {EmptyChannelError} if the channel is empty (never updated yet), or doesn't support checkpoints.
     * @returns {CheckpointType | undefined}
     */
    abstract checkpoint(): CheckpointType | undefined;
    /**
     * Mark the current value of the channel as consumed. By default, no-op.
     * A channel can use this method to modify its state, preventing the value
     * from being consumed again.
     *
     * Returns True if the channel was updated, False otherwise.
     */
    consume(): boolean;
    /**
     * Notify the channel that the Pregel run is finishing. By default, no-op.
     * A channel can use this method to modify its state, preventing finish.
     *
     * Returns True if the channel was updated, False otherwise.
     */
    finish(): boolean;
    /**
     * Return True if the channel is available (not empty), False otherwise.
     * Subclasses should override this method to provide a more efficient
     * implementation than calling get() and catching EmptyChannelError.
     */
    isAvailable(): boolean;
}
export declare function getOnlyChannels(channels: Record<string, BaseChannel>): Record<string, BaseChannel>;
export declare function emptyChannels<Cc extends Record<string, BaseChannel>>(channels: Cc, checkpoint: ReadonlyCheckpoint): Cc;
export declare function createCheckpoint<ValueType>(checkpoint: ReadonlyCheckpoint, channels: Record<string, BaseChannel<ValueType>> | undefined, step: number, options?: {
    id?: string;
}): Checkpoint;