import type { Validator } from "../util/validate.js";
/** Options allowed by a `Schema` instance. */
export type SchemaOptions = {
    /** Title of the schema, e.g. for using as the title of a corresponding field. */
    readonly title?: string | undefined;
    /** Description of the schema, e.g. for using as a description in a corresponding field. */
    readonly description?: string | undefined;
    /** Placeholder of the schema, e.g. for using as a placeholder in a corresponding field. */
    readonly placeholder?: string | undefined;
    /** Default value for the schema if `validate()` is called with an `undefined` value. */
    readonly value?: unknown;
};
/**
 * Schema is an object instance with a `validate()` method.
 * - Type `T` represents the type of value `validate()` returns.
 * - `validate()` returns `Invalid` if value was not valid.
 */
export declare abstract class Schema<T = unknown> implements Validator<T> {
    /** Title of the schema, e.g. for using as the title of a corresponding field. */
    readonly title: string | undefined;
    /** Description of the schema, e.g. for using as a description in a corresponding field. */
    readonly description: string | undefined;
    /** Placeholder of the schema, e.g. for using as a placeholder in a corresponding field. */
    readonly placeholder: string | undefined;
    /** Default value for the schema if `validate()` is called with an `undefined` value. */
    readonly value: unknown;
    constructor({ title, description, placeholder, value }: SchemaOptions);
    /** Every schema must implement a `validate()` method. */
    abstract validate(unsafeValue: unknown): T;
}