/** One tag match, like tags.c's struct tag. */
export interface Tag {
    file: string;
    /** 1-based line number; 0 when the tag uses a search pattern. */
    linenum: number;
    pattern: string | null;
    /** True when the pattern ended with `$` (must match to EOL). */
    endline: boolean;
}
/** Registers a seekable input's complete-file tag jump. */
export declare function onSourceTagJump(jump: ((tag: Tag) => boolean) | null): void;
/** Lets the active source handle the current tag before array lookup. */
export declare function jumpSourceTag(): boolean;
/** The number of loaded tag matches, like ntags(). */
export declare const ntags: () => number;
/** The 1-based current tag sequence, like curr_tag(). */
export declare const currTag: () => number;
/** The current tag's file name, for the jump. */
export declare const currTagFile: () => string | null;
/** Forgets the tag list, like cleantags(). */
export declare function resetTags(): void;
/** Records a startup -t, to be resolved once option scanning ends. */
export declare function setPendingTag(name: string): void;
/**
 * Resolves a startup -t, the way main.c does after scan_option: look the
 * tag up and ask the pager to jump, reporting less's message on failure.
 */
export declare function resolvePendingTag(): string | null;
/** Asks the pager to jump to the current tag. */
export declare function requestTagJump(): void;
/** Registers the pager's tag jump, running one queued by $LESS -t. */
export declare function onTagJump(fn: (() => void) | null): void;
/**
 * Loads the matches for a tag, like tags.c's findtag: the ctags file
 * named by -T, or global(1) output for the GTAGS-family names.
 *
 * @param tag - The tag to look up.
 * @returns null on success, or the less error message.
 */
export declare function findTag(tag: string): string | null;
/**
 * Steps through the tag matches (t / T), like nexttag/prevtag: each
 * step past either end stays put and reports null, non-circular.
 *
 * @param delta - 1 for the next match, -1 for the previous.
 * @param n - How many matches to step.
 * @returns The landed tag, or null when the list ran out.
 */
export declare function stepTag(delta: 1 | -1, n: number): Tag | null;
/**
 * Finds the current tag's row in the opened file, like ctagsearch: a
 * line-number tag jumps directly, a pattern tag scans for a line
 * starting with the (possibly truncated) pattern.
 *
 * @param content - The tag file's lines.
 * @returns The 0-based row, or null when the tag is not found.
 */
export declare function tagRow(content: string[]): number | null;