/**
 * Returns how many extra sub-rows a line will take if it overflows screen
 * width.
 *
 * - Returns 0 if line-chopping is enabled.
 * - Styled or Unicode lines use the cached layout, so the count always
 *   matches what the renderer actually emits.
 *
 * @param line - The string to measure.
 * @returns Number of sub-rows needed to display the line.
 */
export declare function maxSubRow(line: string): number;
/** Registers the selected link's row/offset for display styling. */
export declare function setOsc8Display(at: {
    row: number;
    start: number;
} | null): void;
/** The raw line a display line was derived from, if it still differs. */
export declare const sourceLine: (display: string) => string | undefined;
/**
 * How many DISPLAYED characters the first `count` raw characters
 * produce, style codes excluded.
 *
 * less needs no such function: it stores one display char at a time and
 * tags each with its source position - a tab's spaces all carry the
 * tab's (store_tab, line.c:1056), a caret pair the control char's
 * (store_prchar, line.c:1069). Transforming the prefix answers the
 * same question, and only match boundaries ever ask.
 */
export declare function displayPrefixLength(raw: string, count: number): number;
/**
 * The raw index whose displayed prefix is `shown` characters long -
 * the inverse of displayPrefixLength, for turning a display position
 * back into the source position less would have used.
 */
export declare function sourceIndexAt(raw: string, shown: number): number;
/**
 * The style codes still in force at a character index, so a line can
 * be resumed part-way and still look right - less carries the same
 * state forward in shifted_ansi (line.c:282) when it shifts a line.
 */
export declare function openStyleAt(line: string, index: number): string;
/**
 * The display text of a single line, the transform memoized.
 *
 * transformContent still runs unmemoized over a screen's worth of
 * lines: it is called once per frame there, and the -s squeeze it
 * applies depends on the lines around each one, which a per-line memo
 * cannot see.
 */
export declare function displayLine(raw: string): string;
export declare function transformContent(lines: string[]): string[];
/**
 * The end of the escape run starting at `start`, like cvt_text
 * consuming an ansi_start sequence (cvt.c:79): characters go while
 * ansi_step answers ANSI_MID, and the one that ends the run is taken
 * too - whether it ended it properly (ANSI_END) or aborted it
 * (ANSI_ERR). That is why ESC[K and ESC(B vanish entirely and not
 * just their valid prefix.
 *
 * @param line - The raw line.
 * @param start - Index of the ESC.
 * @returns The index after the run, or `start` when none begins here.
 */
export declare function ansiRunEnd(line: string, start: number): number;
/**
 * The prompt line through the same char machinery as content, like
 * less's prompt() handing pr_string's result to load_line (command.c),
 * which pappends it character by character exactly as forw_line does
 * a file line: tabs expand to their stops and control characters take
 * caret notation instead of reaching the terminal.
 *
 * The prototype's literal bytes are NOT converted while the prompt is
 * being built - less's ap_char stores them raw (5a369ed, whose whole
 * point was that routing them through ap_str corrupts multibyte
 * chars). The conversion belongs here, at the draw.
 */
export declare function transformPrompt(line: string): string;
/**
 * less's do_append recognizes an ANSI sequence when ctldisp is ONPLUS
 * *or* the char has no file position (line.c:1302) - and a prompt is
 * appended with NULL_POSITION, so its escapes are always live. When one
 * is there, load_line then leaves the line's own attributes alone
 * instead of colouring the whole prompt standout (line.c:1950).
 */
export declare function promptHasAnsi(line: string): boolean;
/**
 * Calculates the total visual width of a string based on terminal character
 * widths.
 *
 * @param line - The input string to measure.
 * @returns The total visual width of the string in terminal columns.
 */
export declare function visualWidth(line: string): number;
/**
 * Closes a display line, like less's add_attr_normal from pdone
 * (line.c:1426, called at line.c:1482 and :1499).
 *
 * Under -R less appends a literal "\033[m" to EVERY line, open attribute
 * or not - it writes those three bytes itself rather than asking
 * terminfo, and stores them zero-width, so they neither cost a column
 * nor depend on the terminal. That is what keeps an unclosed colour in
 * the file from bleeding down the screen. Its companion "\033]8;;\e\\"
 * goes out only inside an OSC 8 link, which we do not track across the
 * line end and so never emit.
 *
 * Every other ctldisp leaves the line alone in less, because no file
 * escape survives to that point: only ours can be open, and the reset
 * below closes it.
 *
 * @param line - The line to terminate.
 * @returns The line with styles guaranteed closed.
 */
export declare function withReset(line: string): string;
/**
 * Splits a line into grapheme clusters.
 *
 * - Keeps multi-code-point sequences (ZWJ emoji, variation selectors,
 *   combining marks) together as single units.
 *
 * @param line - The string to split.
 * @returns Array of grapheme clusters.
 */
export declare const splitChars: (line: string) => string[];
/**
 * Checks whether a given segment consists entirely of ASCII characters.
 *
 * - Matches characters in the range 0x00 to 0x7F.
 * - Used to determine whether fast-path rendering can be applied.
 *
 * @param segment - A string segment to check.
 * @returns Whether the segment is pure ASCII.
 */
export declare const isAscii: (segment: string) => boolean;
/**
 * Checks whether a given string contains ANSI style codes.
 *
 * @param line The input string to test.
 * @returns `true` if ANSI style codes are present, otherwise `false`.
 */
export declare const isStyled: (line: string) => boolean;