omnimatch/dist/index.d.ts

TypeScript tagged-union utility knife

/**
 * Delegate handling of an input to a function based on the value of a discriminant property.
 *
 * The value of the input's discriminant is used to index into the pattern to retrieve a
 * function to handle the input.
 *
 * If no entry exists in the pattern for the discriminant of the input, then `undefined` is
 * returned. If no `discriminant` is provided, then the string "kind" is used as the default
 * discriminant.
 *
 * @param input a value with a type discriminated by the {@link discriminator}
 * @param pattern a map from discriminator values to a delegate function to handle that value
 * @param discriminant the property name to use as the discriminant (`"kind"` if not provided)
 */
export declare function match<DiscriminatedUnion extends {
    [K in Discriminant]: string | number;
}, Pattern extends Partial<{
    [K in DiscriminatedUnion[Discriminant]]: (v: Extract<DiscriminatedUnion, {
        kind: K;
    }>) => any;
}>, Discriminant extends string | number = "kind">(input: DiscriminatedUnion, pattern: Exclude<keyof Pattern, DiscriminatedUnion[Discriminant]> extends never ? Pattern : Partial<{
    [K in DiscriminatedUnion[Discriminant]]: (v: Extract<DiscriminatedUnion, {
        kind: K;
    }>) => any;
}>, discriminant?: Discriminant): typeof pattern extends {
    [K in DiscriminatedUnion[Discriminant]]: (v: Extract<DiscriminatedUnion, {
        kind: K;
    }>) => infer Res;
} ? string extends DiscriminatedUnion[Discriminant] ? Res | undefined : unknown extends Res ? undefined : Res : typeof pattern extends Partial<{
    [K in DiscriminatedUnion[Discriminant]]: (v: Extract<DiscriminatedUnion, {
        kind: K;
    }>) => infer Res;
}> ? unknown extends Res ? undefined : Res | undefined : never;
export declare function factory<Union extends {
    [K in Discriminant]: string | number;
}, Discriminant extends string | number = "kind">(discriminant?: Discriminant): {
    [K in Union[Discriminant]]: (fields: {
        [Field in Exclude<keyof Extract<Union, {
            kind: K;
        }>, Discriminant>]: Extract<Union, {
            kind: K;
        }>[Field];
    }) => Extract<Union, {
        kind: K;
    }>;
};