/**
 * The header row of a spreadsheet, as a column index → name map.
 *
 * A map rather than an array, so that a blank header in the middle of the row
 * can be dropped without moving the names after it: with an array compacted by
 * `filter(Boolean)`, every later name shifts one column left and each value lands
 * in its neighbour's field.
 */
export interface SheetHeaders {
    /** Column index (0-based) → the field name that column feeds. */
    byColumn: Map<number, string>;
    /** The names in column order: the import's `propertiesOrder`. */
    order: string[];
}
/** A cell as the readers hand it over: a primitive, or null when empty. */
export type SheetCell = string | number | boolean | Date | null;
/**
 * Name the columns from the header row.
 *
 * - A blank header over a column that holds data is named `ColumnN` after its
 *   position, so its values are kept; over an empty column (a trailing delimiter,
 *   a spacer) it is left out.
 * - A repeated name gets a suffix, `name`, `name_1`, `name_2`, as SheetJS did.
 *   Without one, the second column's values overwrote the first's and a column of
 *   data disappeared.
 * - A `__proto__` header is left out: it would be the prototype setter, not a key.
 */
export declare function getWorksheetHeaders(headerRow: readonly SheetCell[], dataRows?: ReadonlyArray<readonly SheetCell[]>): SheetHeaders;
/**
 * Turn a sheet's rows into one object per record, keyed by the header row.
 *
 * The header row is the first row with anything in it, so a table that starts
 * lower down the sheet reads as it did with SheetJS. A wholly empty row is not a
 * record, and an empty cell contributes no key: the import treats "absent" and
 * "blank" differently, and only an absent key leaves a collection's default value
 * in place.
 */
export declare function sheetRowsToObjects(rows: ReadonlyArray<readonly SheetCell[]>): {
    headers: string[];
    data: Record<string, SheetCell>[];
};