export declare class AsyncLineIterator implements AsyncIterableIterator<Uint8Array> {
    private readonly source;
    private buf;
    private exhausted;
    constructor(source: AsyncIterable<Uint8Array> | AsyncIterator<Uint8Array>);
    [Symbol.asyncIterator](): AsyncIterableIterator<Uint8Array>;
    next(): Promise<IteratorResult<Uint8Array>>;
    readline(): Promise<Uint8Array | null>;
    /**
     * Read up to (not including) `delim`, or to EOF. Returns the bytes and
     * whether the delimiter was found (false means EOF, which `read`/
     * `mapfile` report as status 1).
     */
    readUntil(delim: number): Promise<[Uint8Array<ArrayBuffer>, boolean]>;
    /**
     * Read at most `count` characters, stopping early at `delim` (null
     * reads through delimiters). `read -n` is the delimited form, `read
     * -N` the null one. The delimiter is consumed and not returned.
     * Returns the bytes and whether the read ended on its own terms
     * rather than EOF.
     *
     * Characters, not bytes: bash counts them in the shell's locale, so
     * `read -n 1` on `éx` assigns `é` and leaves `x`. Counting bytes
     * would hand back half a character and leave the other half to
     * corrupt the next read.
     */
    readChars(count: number, delim: number | null): Promise<[Uint8Array<ArrayBuffer>, boolean]>;
}
/**
 * How many bytes `data`'s first character spans, decoded as UTF-8.
 *
 * Always at least one and never more than what is there, so a caller
 * stepping by this never splits a character and never stalls. Bytes that
 * decode to one replacement character answer 1, which is what a
 * fatal:false TextDecoder makes of them: a stray continuation byte, a
 * lead the encoding never uses, and a sequence cut short by a byte that
 * cannot continue it.
 */
export declare function charWidth(data: Uint8Array): number;
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