type QuackDSL = string;
/**
 * Wraps a function with runtime validation based on a given Quack signature.
 *
 * This allows you to enforce that the function matches a specific structure
 * (both syntactically and semantically) based on the Quack DSL. If the function
 * was already annotated via `quackable()`, the signature is checked for compatibility.
 *
 * - If the function is not annotated, the signature is enforced via `zod` wrapper.
 * - If the function is annotated and matches the expected signature, it's either:
 *    - used as-is (`strict = false`)
 *    - or rewrapped with validation (`strict = true`)
 * - If the function is annotated but does not match, an error is thrown.
 *
 * @param expected - A Quack DSL string describing the expected function signature.
 * @param strict - If `true`, wrap the function with runtime validation even if it already matches.
 * @returns A higher-order function that validates or wraps the target function.
 *
 * @example
 * ```ts
 * const greet = expectQuack("(name: string) => void")((name) => console.log(name));
 * greet("Alice"); // valid
 * greet(123);     // throws Zod validation error
 * ```
 */
declare const expectQuack: (expected: QuackDSL, strict?: boolean) => <Q extends (...args: any[]) => any>(fn: Q) => Q;
/**
 * Validates or wraps an entire object to ensure that each method matches a declared Quack signature.
 *
 * This is effectively a "duck typing contract enforcement" tool. Each method in the object
 * is validated against its corresponding expected Quack DSL. You can choose whether to rewrap
 * matched functions with runtime validation using the `strict` flag.
 *
 * @param expected - A mapping of method names to expected Quack DSL signatures.
 * @param strict - If `true`, wrap even matching methods with Zod validation.
 * @returns A higher-order function that returns a cloned object with validated/wrapped methods.
 *
 * @example
 * ```ts
 * const duck = expectDuck({
 *   greet: "(name: string) => void",
 *   add: "(x: number, y: number) => number"
 * })({
 *   greet(name) { console.log(name); },
 *   add(x, y) { return x + y; }
 * });
 * ```
 */
declare const expectDuck: <D extends { [K in string]: QuackDSL; }>(expected: D, strict?: boolean) => <O extends { [K in keyof D]: (...args: any[]) => any; }>(obj: O) => { [K in keyof D]: O[K]; };

type ParsedType = "number" | "string" | "boolean" | "null" | "undefined" | "dontcare" | "void" | ArrayType | TupleType | PromiseType | FunctionType;
type ArrayType = {
    type: "array";
    element: ParsedType;
};
type TupleType = {
    type: "tuple";
    elements: ParsedType[];
};
type PromiseType = {
    type: "promise";
    inner: ParsedType;
};
type ParameterType = {
    optional: boolean;
    type: ParsedType;
};
type FunctionType = {
    type: "function";
    async: boolean;
    parameters: ParameterType[];
    return: ParsedType;
};

type QuackAst = FunctionType;
/**
 * Parses a string representation of a function signature into a QuackAst (intermediate representation).
 *
 * @param fnSig - A string in the format of a function signature, e.g. "(x: number, y: string) => boolean"
 * @returns A QuackAst object representing the parsed function signature.
 */
declare function quackAstOf(fnSig: string): QuackAst;
/**
 * Retrieves the QuackAst metadata from a previously marked function.
 *
 * @param fn - A function which may have been decorated or marked with `quackable`.
 * @returns The QuackAst if present, otherwise undefined.
 */
declare function quackAstFrom(fn: Function): QuackAst | null;
/**
 * Checks if a function has been marked as quackable (i.e., has QuackAst metadata).
 *
 * @param fn - A function to check.
 * @returns True if the function has a QuackAst attached, false otherwise.
 */
declare function isQuackable(fn: Function): boolean;
/**
 * Marks a function or class method with a quackable signature.
 *
 * This allows later validators (like `expectQuack`) to verify that
 * the function is intended to match a specific signature contract at runtime.
 *
 * ### Usage (Function)
 * ```ts
 * const add = quackable("(x: number, y: number) => number")(
 *   (x, y) => x + y
 * );
 * ```
 *
 * ### Usage (Class Method - Legacy Decorator)
 * ```ts
 * class MyClass {
 *   @quackable("(name: string) => void")
 *   greet(name: string) { console.log(name); }
 * }
 * ```
 *
 * ### Usage (Class Method - ECMA 2022 Decorator)
 * ```ts
 * class MyClass {
 *   greet = quackable("(name: string) => void")(function(name: string) {
 *     console.log(name);
 *   });
 * }
 * ```
 *
 * @param sig - The expected function signature in string form.
 * @returns A decorator or a function wrapper that marks the target with QuackAst metadata.
 */
declare function quackable<I extends any[], O>(sig: string): (fn: (...args: I) => O) => (...args: I) => O;
declare function quackable(sig: string): MethodDecorator;

export { expectDuck, expectQuack, isQuackable, quackAstFrom, quackAstOf, quackable };
export type { QuackAst, QuackDSL };