import { BlockFile } from './blockFile';
/**
 * On-demand line reading over a BlockFile, ported from less input.c's
 * forw_line/back_line: lines materialize from byte positions, so no
 * line index or full scan is ever required.
 */
/** Pathological lines split at this many bytes (less grows linebuf;
 *  we bound memory instead — the renderer wraps/chops anyway, and
 *  every split segment costs a transform+layout per visible row). */
export declare const MAX_LINE: number;
interface ForwLine {
    text: string;
    /** Start of the next line (past the newline), or the file size. */
    next: number;
    /** True when the cap split a newline-less monster line. */
    split: boolean;
}
interface BackLine {
    text: string;
    /** Start position of the returned line. */
    start: number;
}
/**
 * Reads the line starting at `pos`, like forw_line.
 *
 * The result is shared with the other callers reading the same
 * position, so it must be treated as read-only.
 */
export declare function forwLine(bf: BlockFile, pos: number, noScan?: boolean): ForwLine | null;
/**
 * Reads the line that ends just before line-start `pos`, like
 * back_line walking to the previous newline.
 *
 * @param pos - A known line start (0 returns null).
 */
export declare function backLine(bf: BlockFile, pos: number): BackLine | null;
/**
 * The start of the last line of the file, like less's end-of-file seek
 * for G: a trailing newline belongs to the line before it.
 */
export declare function lastLineStart(bf: BlockFile): number;
export {};