/**
 * Validation utilities for DuskMoon form elements
 *
 * Provides composable validator functions that can be used with
 * any form element supporting ValidationState and errorMessage props.
 *
 * @example
 * ```ts
 * import { validate, validators } from '@duskmoon-dev/el-base';
 *
 * const result = validate('hello@example.com', [
 *   validators.required('Email is required'),
 *   validators.email('Must be a valid email'),
 * ]);
 *
 * // result = { state: 'valid', message: undefined }
 *
 * inputEl.validationState = result.state;
 * inputEl.errorMessage = result.message ?? '';
 * ```
 */
import type { ValidationState } from './types.js';
/**
 * Result of a validation check
 */
export interface ValidationResult {
    state: NonNullable<ValidationState>;
    message: string | undefined;
}
/**
 * A validator function takes a value and returns an error message
 * if invalid, or undefined/null if valid.
 */
export type Validator<T = string> = (value: T) => string | undefined | null;
/**
 * Run a value through a list of validators, returning on the first failure.
 * Returns { state: 'valid' } if all pass, { state: 'invalid', message } on first failure.
 */
export declare function validate<T = string>(value: T, rules: Validator<T>[]): ValidationResult;
/**
 * Run a value through an async validator.
 * Sets state to 'pending' during execution.
 */
export declare function validateAsync<T = string>(value: T, rules: Validator<T>[], asyncRule: (value: T) => Promise<string | undefined | null>): Promise<ValidationResult>;
/**
 * Built-in validators for common patterns
 */
export declare const validators: {
    /** Requires a non-empty value */
    readonly required: (message?: string) => Validator<string>;
    /** Requires a minimum string length */
    readonly minLength: (min: number, message?: string) => Validator<string>;
    /** Requires a maximum string length */
    readonly maxLength: (max: number, message?: string) => Validator<string>;
    /** Requires a value matching a regex pattern */
    readonly pattern: (regex: RegExp, message?: string) => Validator<string>;
    /** Requires a valid email address */
    readonly email: (message?: string) => Validator<string>;
    /** Requires a numeric value within a range */
    readonly range: (min: number, max: number, message?: string) => Validator<string>;
    /** Custom validator from a predicate function */
    readonly custom: <T = string>(predicate: (value: T) => boolean, message: string) => Validator<T>;
};
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