import { Graph } from "./types";
/**
 * A graph for storing named nodes. It extensively makes use of unordered
 * JavaScript objects in order to efficiently query nodes, insert new ones and
 * delete existing ones.
 *
 * Much like a ES6 Map or Set, this graph type guarantees that insertion order
 * is preserved for vertices. For example, if you add node A after B,
 * `getVertices()` will always retun `['B', 'A']`.
 */
export declare class NullObjectGraph<V extends PropertyKey> implements Graph<V> {
    private nodes;
    private targetNodes;
    private sourceNodes;
    edgeCount: number;
    vertexCount: number;
    constructor(iterable?: Iterable<[V, V]>);
    hasEdge(a: V, b: V): any;
    addEdge(source: V, target: V): void;
    deleteEdge(a: V, b: V): void;
    getSourceVertices(node: V): any;
    getTargetVertices(node: V): any;
    getVertices(): Set<V>;
    addVertex(v: V): void;
    getEdges(): Iterable<[V, V]>;
}
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