import { Document } from './document';
import { DocumentComparator } from './document_comparator';
import { DocumentKey } from './document_key';
/**
 * DocumentSet is an immutable (copy-on-write) collection that holds documents
 * in order specified by the provided comparator. We always add a document key
 * comparator on top of what is provided to guarantee document equality based on
 * the key.
 */
export declare class DocumentSet {
    /**
     * Returns an empty copy of the existing DocumentSet, using the same
     * comparator.
     */
    static emptySet(oldSet: DocumentSet): DocumentSet;
    private comparator;
    private keyedMap;
    private sortedSet;
    /** The default ordering is by key if the comparator is omitted */
    constructor(comp?: DocumentComparator);
    has(key: DocumentKey): boolean;
    get(key: DocumentKey): Document | null;
    first(): Document | null;
    last(): Document | null;
    isEmpty(): boolean;
    /**
     * Returns the index of the provided key in the document set, or -1 if the
     * document key is not present in the set;
     */
    indexOf(key: DocumentKey): number;
    readonly size: number;
    /** Iterates documents in order defined by "comparator" */
    forEach(cb: (doc: Document) => void): void;
    /** Inserts or updates a document with the same key */
    add(doc: Document): DocumentSet;
    /** Deletes a document with a given key */
    delete(key: DocumentKey): DocumentSet;
    isEqual(other: DocumentSet | null | undefined): boolean;
    toString(): string;
    private copy(keyedMap, sortedSet);
}