/**
 * Base64 codec tiers, and the tables they share.
 *
 * Split out of the public `Base64` module for the same reason the hex codec is:
 * a runtime selects one tier at import, so the others are unreachable from a
 * test unless they can be called directly. Keeping them here lets the
 * conformance suite compare every tier a runtime can execute, without widening
 * `Base64`'s public surface.
 *
 * @internal
 */
import * as Errors from '../../Errors.js';
import type * as Bytes from '../../Bytes.js';
/** @internal */
export type Options = {
    /** Whether to pad the encoded string. */
    pad?: boolean | undefined;
    /** Whether to use the URL-safe alphabet. */
    url?: boolean | undefined;
};
/**
 * Encodes via `Uint8Array.prototype.toBase64`, where the runtime has it.
 * `undefined` otherwise, so the conformance suite can ask whether this tier
 * exists rather than inferring it from the runtime.
 *
 * @internal
 */
export declare const fromBytesNative: ((value: Bytes.Bytes, options?: Options) => string) | undefined;
/**
 * Encodes in plain JavaScript, for runtimes without the native method.
 *
 * @internal
 */
export declare function fromBytesLoop(value: Bytes.Bytes, options?: Options): string;
/**
 * Encodes with whichever tier this runtime provides.
 *
 * @internal
 */
export declare function fromBytes(value: Bytes.Bytes, options?: Options): string;
/**
 * `Uint8Array.fromBase64` is deliberately unused.
 *
 * Its `alphabet` option is strict and mutually exclusive -- `base64` refuses
 * `-`/`_`, `base64url` refuses `+`/`/` -- while ox decodes either alphabet
 * transparently. There is no single native call with that behavior, so matching
 * it would mean normalizing the string first or trying both alphabets and
 * throwing on one. Both cost more than they would save, and neither has been
 * measured; the loop is the only decode tier until one is.
 */
/**
 * Decodes in plain JavaScript, for runtimes without the native method.
 *
 * @internal
 */
export declare function toBytesLoop(value: string, bodyEnd: number): Bytes.Bytes;
/**
 * Decodes with whichever tier this runtime provides.
 *
 * @internal
 */
export declare function toBytes(value: string): Bytes.Bytes;
/** Thrown when a Base64 string contains an invalid character. */
export declare class InvalidCharacterError extends Errors.BaseError {
    readonly name = "Base64.InvalidCharacterError";
    constructor({ character }: {
        character: string;
    });
}
/** Thrown when a Base64 string has an impossible length. */
export declare class InvalidLengthError extends Errors.BaseError {
    readonly name = "Base64.InvalidLengthError";
    constructor({ length }: {
        length: number;
    });
}
/** Thrown when a Base64 string contains too many trailing `=` padding characters. */
export declare class InvalidPaddingError extends Errors.BaseError {
    readonly name = "Base64.InvalidPaddingError";
    constructor({ padding }: {
        padding: number;
    });
}
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