/**
 * Represents an optional filter that may be provided as either a single value
 * or multiple values. Normalizes all inputs into a deduplicated array for
 * consistent downstream query usage.
 *
 * This abstraction separates filter presence from stored values, allowing
 * consumers to detect whether filtering logic should be applied at all.
 */
export declare class OptionalFilter<T> {
    private readonly singleValue;
    private readonly multipleValues;
    /**
     * Internal storage for deduplicated filter values.
     */
    private readonly valueSet;
    /**
     * Creates an optional filter from either a single value or an array of values.
     *
     * @param singleValue - Optional single filter value.
     * @param multipleValues - Optional array of filter values.
     */
    constructor(singleValue: T | undefined, multipleValues: T[] | undefined);
    /**
     * Whether this filter was explicitly provided by the caller.
     *
     * True if at least one value was supplied, even if the array is empty.
     */
    get isActive(): boolean;
    /**
     * Returns all deduplicated filter values as an array.
     *
     * Downstream logic can use this to build queries without worrying about
     * whether the original input was a single value or multiple values.
     */
    get values(): T[];
    /**
     * Checks whether a specific value is included in this filter.
     *
     * @param value - The value to test for inclusion.
     * @returns True if the value is present in the filter.
     */
    contains(value: T): boolean;
}