Add Rfc 6570 Expression

 * ```

 */

export type ParamsKeyPath<Params extends Record<string, string>> =

  & ParamsPath<Extract<keyof Params, string>>

  & ParamPath<Extract<keyof Params, string>>

  & string;

/**

 * userPostPath = "/posts/{postId}/users/{userId}"; // ✅ valid

 */

type ParamsPath<Params extends string> = UnionToIntersection<ParamPath<Params>>;

/**

 * Defines a union of all valid RFC 6570 URI Template expressions for a given

 * parameter name.

 *

 * RFC 6570 specifies a syntax for URI templates, allowing for variable

 * expansion. This type captures all Level 1-4 operator expressions for a

 * single, named variable.

 *

 * The supported expression types are:

 * - `{Param}`: Simple string expansion

 * - `+{Param}`: Reserved string expansion

 * - `#{Param}`: Fragment expansion

 * - `{.Param}`: Label expansion with a dot-prefix

 * - `{/Param}`: Path segment expansion

 * - `{;Param}`: Path-style parameter expansion

 * - `{?Param}`: Query component expansion

 * - `{&Param}`: Query continuation expansion

 *

 * @template Param The name of the parameter to be used in the expressions.

 * @example

 * ```ts

 * type UserIdExpression = Rfc6570Expression<"userId">;

 *

 * // The variable `userPath` can be assigned any of the valid expressions.

 * const userPath: UserIdExpression = "{/userId}";

 * ```

 * @see {@link https://tools.ietf.org/html/rfc6570} for the full specification.

 */

type Rfc6570Expression<Param extends string> =

  | `{${Param}}`

  | `{+${Param}}`

  | `{#${Param}}`

  | `{.${Param}}`

  | `{/${Param}}`

  | `{;${Param}}`

  | `{?${Param}}`

  | `{&${Param}}`;

/**

 * Represents a path with a single parameter.

 * The path must have at least one of the parameters in the form of `{paramName}`.

 * userPostPath = "/users/{userId}/posts/{postId}"; // ✅ valid

 * userPostPath = "/posts/{postId}/users/{userId}"; // ✅ valid

 */

type ParamPath<Param extends string> = `${string}{${Param}}${string}`;

type ParamPath<Param extends string> = `${string}${Rfc6570Expression<

  Param

>}${string}`;

/**

 * Converts union types to intersection types.

 *