/** How many bytes a reader reads from the file at a time. */
export declare const READ_CHUNK_BYTES: number;
export type LineSplitter = {
    /** The complete lines finished by `chunk`. The bytes after the last
     *  newline are kept as the partial line, for a later push to complete. */
    push(chunk: Buffer): string[];
    /** For a source that has ended: the partial last line as one more batch of
     *  lines. See `finishedTail`. */
    finish(): string[];
    /** How many bytes the partial line holds. */
    pendingBytes(): number;
    /** Forget the partial line. */
    reset(): void;
};
export declare function makeLineSplitter(): LineSplitter;
export type LineChunk = {
    lines: string[];
    /** True when the reader has reached the end of the file as it is now. */
    atEnd: boolean;
};
export type LineReader = {
    /** Read at most `READ_CHUNK_BYTES` and return the lines that finished. */
    readChunk(): LineChunk;
    /** Read to the end of the file as it is now, handing over the lines that
     *  finish one chunk at a time, so no caller holds the whole file. */
    readToEnd(onLines: (lines: string[]) => void): void;
    /** For a finished file: the partial last line as one more batch of lines,
     *  under the rule in `finishedTail`. The reader keeps the bytes, so a viewer
     *  that starts following the file afterwards can still complete the line. */
    finish(): string[];
    /** How many bytes the partial last line holds. */
    pendingBytes(): number;
    /** Close the file. A read that reaches the end closes it by itself, so only
     *  a caller that stops early needs this. */
    close(): void;
};
/**
 * A reader of a file that may still be growing. Each read picks up where the
 * last one stopped, and the file stays open from one read to the next until a
 * read reaches the end. `startOffset` is where reading begins: 0 reads the
 * whole file; `currentFileSize(path)` reads only what is appended later. A
 * missing file reads as empty. A file that shrank (rotated or truncated)
 * rewinds to the start, and that read returns no lines.
 */
export declare function makeLineReader(path: string, startOffset?: number): LineReader;
/** The file's size right now; 0 when it does not exist yet. */
export declare function currentFileSize(path: string): number;