/**
 * One piece of a paragraph handed to {@link segmentLevels}: a plain text run, or
 * an atomic object (inline image / math box). A segment may carry a run-level
 * direction override, applied via explicit RLE/LRE…PDF wrapping.
 */
export interface BidiSegment {
    /** Text content; ignored when `object` is true. */
    readonly text: string;
    /** Atomic neutral object (inline image / math box) — counts as ONE position. */
    readonly object?: boolean;
    /** Run-level direction override (`w:rtl`). */
    readonly rtl?: boolean;
}
/**
 * Resolve UAX #9 embedding levels for a paragraph described as a flat list of
 * {@link BidiSegment}s, returning one level per "real" position: one per text
 * code point, one per object. Carries the explicit-formatting protocol: an `rtl`
 * segment is wrapped in RLE…PDF (an LTR segment inside an RTL paragraph in
 * LRE…PDF) so run-level direction overrides neutral resolution, and each object
 * participates as U+FFFC (Object Replacement Character). The inserted control
 * characters are not reflected in the output — their levels are projected back
 * onto the real positions only.
 *
 * @param segments The paragraph's segments, in logical order.
 * @param baseDir  The paragraph base direction.
 * @returns One embedding level per real position (text code point or object).
 */
export declare function segmentLevels(segments: ReadonlyArray<BidiSegment>, baseDir: 'ltr' | 'rtl'): Array<number>;