import { PdfRef } from './objects.js';
import { PdfDocument } from './writer.js';
/**
 * Standard structure types (ISO 32000-1 Table 333/337). Every type here is
 * recognised without a `/RoleMap`, so the builder never emits one.
 */
export type StructType = 'Document' | 'Part' | 'Sect' | 'H1' | 'H2' | 'H3' | 'H4' | 'H5' | 'H6' | 'P' | 'L' | 'LI' | 'Lbl' | 'LBody' | 'Table' | 'TR' | 'TH' | 'TD' | 'Caption' | 'Figure' | 'Link' | 'Note' | 'Span';
interface Mcref {
    readonly pageIndex: number;
    readonly mcid: number;
}
/** One node in the logical structure tree: a {@link StructType} plus its children, marked-content and attributes. */
export declare class StructNode {
    readonly id: number;
    type: StructType;
    readonly children: Array<StructNode>;
    readonly mcrefs: Array<Mcref>;
    /**
     * §14.7.4.3 object references (`/OBJR` kids) — e.g. a Link element pointing at
     * its link annotation. The annotation's own `/StructParent` entry is recorded
     * via {@link StructTreeBuilder.addAnnotParent}.
     */
    readonly objrs: Array<{
        readonly annotRef: PdfRef;
        readonly pageIndex: number;
    }>;
    parent: StructNode | null;
    ref: PdfRef | null;
    /** Alternate text (`/Alt`, §14.9.4) — required on Figure for PDF/A-1a. */
    alt: string | null;
    /** Natural language (`/Lang`) when it differs from the document default. */
    lang: string | null;
    /**
     * §14.8.5.2 Table attribute (emitted via a `/A` attribute object on the cell):
     * `/Scope` on a TH (Row/Column) so assistive tech binds headers to data cells.
     */
    scope: 'Row' | 'Column' | null;
    /** §14.8.5.2 — `/ColSpan` when the cell spans more than one column (gridSpan). */
    colSpan: number | null;
    /** §14.8.5.2 — `/RowSpan` when the cell spans more than one row (vertical merge). */
    rowSpan: number | null;
    /**
     * @param id   The node's index, used for deterministic id assignment and `/ID`.
     * @param type The structure type (mutable, so the renderer can retag).
     */
    constructor(id: number, type: StructType);
}
/**
 * Builds the tagged-PDF logical structure tree (ISO 32000-1 §14.7–14.8): a
 * `/StructTreeRoot` over a tree of {@link StructNode}s, tied back to page
 * marked-content via MCRs and the `/ParentTree`. A generic emitter — the
 * structure-type mapping policy lives in the renderer. Object ids are assigned by
 * a deterministic pre-order DFS so identical input yields byte-identical output.
 */
export declare class StructTreeBuilder {
    private readonly nodes;
    /** The root logical element (the single `/Document` under `/StructTreeRoot`). */
    readonly root: StructNode;
    constructor();
    /**
     * Create a node of `type` as the last child of `parent`.
     *
     * @param parent The parent node, or `null` for a free node (only the root is
     *   created that way).
     * @returns The new node.
     */
    create(type: StructType, parent: StructNode | null): StructNode;
    /**
     * Look up a node by its id.
     *
     * @throws Error if no node has that id.
     */
    node(id: number): StructNode;
    /**
     * Record that marked content `mcid` on page `pageIndex` is the content of node
     * `nodeId`. Called from the emit phase as MCIDs are assigned.
     */
    addMcref(nodeId: number, pageIndex: number, mcid: number): void;
    /**
     * §14.7.4.4: an annotation's `/StructParent` key maps DIRECTLY to its owning
     * `/StructElem` in the parent tree (a scalar entry, unlike the per-page MCID
     * arrays). The emit phase allocates keys above the page indices.
     */
    private readonly annotParents;
    /**
     * Register that annotation parent-tree key `key` resolves to node `nodeId`.
     *
     * @see StructTreeBuilder.annotParents
     */
    addAnnotParent(key: number, nodeId: number): void;
    /**
     * Emit the `/StructTreeRoot`, every `/StructElem`, and the `/ParentTree`. Must
     * run after all pages are added (so `pageRefs` is complete) and after every
     * {@link StructTreeBuilder.addMcref} call.
     *
     * @param pageRefs The page object references, indexed by page number.
     * @returns A reference to the `/StructTreeRoot`, for the catalog.
     */
    emit(doc: PdfDocument, pageRefs: ReadonlyArray<PdfRef>): PdfRef;
}
export {};