import GridData from '../grid.js';
import { RuleState } from '../primitives.js';
import Instruction from '../instruction.js';
export interface SearchVariant {
    description: string;
    rule: Rule;
}
export default abstract class Rule extends Instruction {
    abstract validateGrid(grid: GridData): RuleState;
    abstract get searchVariants(): SearchVariant[];
    searchVariant(): SearchVariant;
    get visibleWhenSolving(): boolean;
    /**
     * Whether only one instance of this rule is allowed in a grid.
     */
    get isSingleton(): boolean;
}
export declare const instance: undefined;
