urns/lib/map-fields.d.ts

An RFC 8141 compliant URN library with some interesting type related functionality

/**
 * This function is not strictly related to URNs.  But it is useful in conjunction with the `transform`
 * functionality in the `URNSpace` class.  Specifically, the `decode` function takes an array
 * of field names as an argument and returns a function that, when given a colon separated list of
 * strings (*i.e.,* the typical construction of a hierarchal namespace specific string from a URN),
 * returns an object where each string in the list is mapped to the respective field.  For example,
 *
 * ```
 * decode(["a", "b"])("foo:bar") => { "a": "foo", "b": "bar" }
 * ```
 *
 * This provides an easy means to transform the NSS from the URN into an object.
 *
 * NB - This function is overloaded so that it can provide a type safe mapping from
 * the string names provided as an argument to `decode` and the resulting object
 * type returned after processing the NSS>.  Only the first 5 cases are implemented
 * here.  If you have an NSS with more than 5 components, you'd need to write a
 * special transform function.  But the `URNSpace` class will accept any transform
 * function, it doesn't need to be derived from this one.
 *
 * @param x Array of field names
 */
export declare function mapFields<T extends string>(x: [T]): (nss: string) => Record<T, string>;
export declare function mapFields<T1 extends string, T2 extends string>(x: [T1, T2]): (nss: string) => Record<T1 | T2, string>;
export declare function mapFields<T1 extends string, T2 extends string, T3 extends string>(x: [T1, T2, T3]): (nss: string) => Record<T1 | T2 | T3, string>;
export declare function mapFields<T1 extends string, T2 extends string, T3 extends string, T4 extends string>(x: [T1, T2, T3, T4]): (nss: string) => Record<T1 | T2 | T3 | T4, string>;
export declare function mapFields<T1 extends string, T2 extends string, T3 extends string, T4 extends string, T5 extends string>(x: [T1, T2, T3, T4, T5]): (nss: string) => Record<T1 | T2 | T3 | T4 | T5, string>;