export interface PositionCacheConfig {
    totalItemsFn: () => number;
    sizeFn: (index: number) => number;
    defaultSizeFn: () => number;
}
/**
 * Cumulative prefix sum cache for O(log n) scroll-to-index lookups.
 *
 * Works for both row heights and column widths. Builds an array where
 * prefixSum[i] = sum of sizes for items 0..i-1.
 * prefixSum[0] = 0, prefixSum[n] = total size of all n items.
 *
 * Binary search on this array converts a pixel offset to an index in O(log n)
 * instead of O(n) linear iteration.
 *
 * @class PositionCache
 */
export declare class PositionCache {
    #private;
    /**
     * The prefix sum array. Contains the cumulative size of all items up to the index.
     *
     * @type {Float64Array|null}
     */
    prefixSum: Float64Array | null;
    /**
     * The total number of items (rows or columns).
     *
     * @type {number}
     */
    totalItems: number;
    /**
     * @param {object} config The configuration object.
     * @param {Function} config.totalItemsFn A function that returns the total number of items (rows or columns).
     * @param {Function} config.sizeFn A function that returns the size for a given index.
     * @param {Function} config.defaultSizeFn A function that returns the default size for items
     *   that return NaN/undefined.
     */
    constructor({ totalItemsFn, sizeFn, defaultSizeFn }: PositionCacheConfig);
    /**
     * Builds the prefix sum by reading the current total items, size function,
     * and default size from the configured providers.
     */
    build(): void;
    /**
     * Returns the cumulative size at an index (sum of items 0..index-1).
     *
     * @param {number} index The item index.
     * @returns {number} The cumulative size before this index.
     */
    getOffset(index: number): number;
    /**
     * Finds the item index at a given pixel offset using binary search.
     *
     * @param {number} offset The pixel offset.
     * @returns {number} The index whose cumulative start position is at or just before the offset.
     *   Returns `0` when there are no items (`totalItems === 0`), including when `offset > 0`.
     */
    findIndexAtOffset(offset: number): number;
    /**
     * Returns the size of a single item at the given index.
     *
     * @param {number} index The item index.
     * @returns {number} The size of the item (difference between consecutive prefix sums).
     */
    getSizeAt(index: number): number;
    /**
     * Builds the prefix sum only when the cache is not yet built or the item
     * count has changed.
     */
    ensureBuilt(): void;
    /**
     * Returns the total size of all items.
     *
     * @returns {number}
     */
    getTotalSize(): number;
    /**
     * Invalidates the cache so it will be rebuilt on the next
     * {@link PositionCache#ensureBuilt} call.
     */
    invalidate(): void;
    /**
     * Returns whether the cache has been built.
     *
     * @returns {boolean}
     */
    isBuilt(): this is PositionCache & {
        prefixSum: Float64Array;
    };
}