import { Bag } from "../../utils/bag";
import { State } from "../vm";
import { IDatabase } from "./database";
import { FunctionRelationFn, MappedRelation, Predicate } from "./predicate";
import { UnificationEnvironment } from "./unification";
export declare class FunctionLayer extends Bag<string, FunctionRelationFn> {
    readonly parent: FunctionLayer | null;
    constructor(parent: FunctionLayer | null);
    try_lookup(name: string): FunctionRelationFn | null;
}
export declare class DatabaseLayer implements IDatabase {
    readonly parent: IDatabase;
    readonly functions: FunctionLayer;
    constructor(parent: IDatabase, functions: FunctionLayer);
    add(name: string, relation: MappedRelation): void;
    update(name: string, relation: MappedRelation): void;
    try_lookup(name: string): MappedRelation | null;
    lookup(name: string): MappedRelation;
    search(state: State, predicate: Predicate, initial_environment: UnificationEnvironment): UnificationEnvironment[];
}