export interface DCommand {
    isStorable(): boolean;
    isClear(): boolean;
    isClean(): boolean;
    /**
     * Called to executed this command.
     *
     * @return true if executed successfully
     */
    execute(): boolean;
    /**
     * Called to merge the target command and this command.
     * Returns true if merged successfully.
     *
     * @param target a command to be merged
     * @return true if merged successfully
     */
    merge(target: DCommand): boolean;
    isMerged(): boolean;
    redo(): boolean;
    undo(): boolean;
    destroy(): void;
}