export declare function parseByteCount(raw: string): number;
export declare function parseN(n: string | null): [number, boolean];
export interface TailCounts {
    lines: number | null;
    fromLine: number | null;
    byteCount: number | null;
    fromByte: number | null;
}
/**
 * Fill in whatever a caller left off a `TailCounts`.
 *
 * The struct is a plain object, so a caller that omits a field — or a
 * JavaScript one that passes something else entirely — supplies undefined,
 * and a bare `!== null` test waves that straight into the first branch,
 * where `slice(NaN)` quietly returns the whole input. Python's twin is a
 * dataclass whose four fields all default to None and has no such hole;
 * reading every field through `?? null` gives this side the same floor.
 */
export declare function normalizeCounts(counts: TailCounts): TailCounts;
/**
 * Split tail's `-n`/`-c` values by which end they count from.
 *
 * GNU gives both flags the same sign grammar: a leading `+` counts forward
 * from the start of the input, 1-indexed, so `+0` and `+1` both mean the
 * whole thing; any other spelling counts back from the end. Every caller
 * used to apply that grammar to `-n` and take the absolute value of `-c`,
 * which silently turned `tail -c +3` into the last three bytes — so the
 * split lives here, once, beside the parser it is built from. Mirrors
 * Python's `parse_counts`.
 */
export declare function parseCounts(nRaw: string | null, cRaw: string | null): TailCounts;
export declare function numberFlagError(cmd: string, nRaw: string | null, cRaw: string | null): string | null;
export declare function tailBytes(data: Uint8Array, rawCounts: TailCounts): Uint8Array;
export declare function countNewlines(data: Uint8Array): number;
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