import { type ValidatorFn } from './core.js';
import type { AccumulatorRange, ExtractLength } from './types.js';
/**
 * Type guard validator that checks if a value is undefined.
 * Returns a ValidatorFn that narrows the type to `undefined` on success.
 *
 * @returns ValidatorFn<undefined> - Validator function with type predicate
 *
 * @example
 * const validator = isUndefined;
 * if (validator(value)) {
 *   // value is narrowed to type: undefined
 * }
 */
export declare const isUndefined: ValidatorFn<undefined>;
/**
 * Type guard validator that checks if a value is null.
 * Returns a ValidatorFn that narrows the type to `null` on success.
 *
 * @returns ValidatorFn<null> - Validator function with type predicate
 *
 * @example
 * const validator = isNull;
 * if (validator(value)) {
 *   // value is narrowed to type: null
 * }
 */
export declare const isNull: ValidatorFn<null>;
/**
 * Type guard validator that checks if a value is a string.
 * Returns a ValidatorFn that narrows the type to `string` on success.
 *
 * @returns ValidatorFn<string> - Validator function with type predicate
 *
 * @example
 * const validator = isString;
 * if (validator(value)) {
 *   // value is narrowed to type: string
 *   const length = value.length;
 * }
 */
export declare const isString: ValidatorFn<string>;
/**
 * Type guard validator that checks if a value is a number.
 * Returns a ValidatorFn that narrows the type to `number` on success.
 *
 * @returns ValidatorFn<number> - Validator function with type predicate
 *
 * @example
 * const validator = isNumber;
 * if (validator(value)) {
 *   // value is narrowed to type: number
 *   const doubled = value * 2;
 * }
 */
export declare const isNumber: ValidatorFn<number>;
/**
 * Type guard validator that checks if a value is a boolean.
 * Returns a ValidatorFn that narrows the type to `boolean` on success.
 *
 * @returns ValidatorFn<boolean> - Validator function with type predicate
 *
 * @example
 * const validator = isBoolean;
 * if (validator(value)) {
 *   // value is narrowed to type: boolean
 *   const negated = !value;
 * }
 */
export declare const isBoolean: ValidatorFn<boolean>;
/**
 * Constraints for bounded number validation.
 * At least one of min or max should be specified for meaningful bounds.
 */
export interface NumberConstraints {
    /** Minimum allowed value (inclusive) */
    min?: number;
    /** Maximum allowed value (inclusive) */
    max?: number;
}
/**
 * Factory function that creates a type guard validator for bounded numbers.
 * Returns a ValidatorFn that narrows the type to `number` and validates range constraints.
 *
 * The returned validator checks that a value is a number and optionally within specified bounds.
 * Provides detailed diagnostic messages for validation failures.
 *
 * @param constraint - Min/max bounds for the number
 * @returns ValidatorFn<number> - Validator function with type predicate and constraint info
 *
 * @example
 * const isPositive = isBoundedNumber({ min: 0 });
 * const isPercentage = isBoundedNumber({ min: 0, max: 100 });
 *
 * if (isPositive(value)) {
 *   // value is narrowed to type: number (and >= 0 at runtime)
 * }
 */
export declare const isBoundedNumber: (constraint: NumberConstraints) => ValidatorFn<number>;
/**
 * Type guard validator for uint8 (unsigned 8-bit integer).
 * Returns a ValidatorFn that narrows the type to `number` and validates 0..255 range.
 *
 * @returns ValidatorFn<number> - Validator function for numbers in range [0, 255]
 *
 * @example
 * const validator = isUint8;
 * if (validator(value)) {
 *   // value is narrowed to type: number (and 0..255 at runtime)
 * }
 */
export declare const isUint8: ValidatorFn<number>;
/**
 * Helper type to generate union of literal numbers from Min to Max.
 *
 * @example
 * NumberRange<0, 3> = 0 | 1 | 2 | 3
 */
type NumberRange<Min extends number, Max extends number> = ExtractLength<AccumulatorRange<Min, Max, unknown>>;
/**
 * Creates a number validator with type-level literal unions for small ranges.
 *
 * Returns a union of exact number literals: `0 | 1 | 2 | ... | Max`.
 * Only use for small ranges (< 10) to avoid TypeScript issues.
 *
 * @example
 * const isSmallNumber = isBoundedNumberUnion({ min: 0, max: 3 });
 * // Returns: (val: unknown) => val is 0 | 1 | 2 | 3
 */
export declare const isBoundedNumberUnion: <Min extends number, Max extends number>(options: {
    min: Min;
    max?: Max;
} | {
    min?: Min;
    max: Max;
}) => ValidatorFn<NumberRange<Min, Max>>;
export {};