/**
 * Simple directional graph.
 */
export declare class DirectionalGraph {
    private verticesAndEdges;
    /**
     * Constructor, optionally copy-constructor.
     * @param verticesAndEdges optional list of vertex-edges tuples - use as a copy constructor to re-hydrate from de-serialized object
     */
    constructor(verticesAndEdges?: [string, string[]][]);
    static fromGraph(graph: DirectionalGraph): DirectionalGraph;
    /**
     * Get all vertices.
     */
    getVertices(): string[];
    /**
     * Get all edges.
     */
    getEdges(): [string, string][];
    addEdge(from: string, to?: string): DirectionalGraph;
    getVerticesWithEdgesFrom(vertex: string): string[] | undefined;
    getVerticesWithEdgesTo(vertex: string): string[];
    getSubtreePointingTo(vertex: string): string[];
    getSubtreePointingFrom(vertex: string): string[];
}