simple-tg/dist/index.d.ts

Simple type guard helpers for TypeScript

declare type Primitives = {
    string: string;
    number: number;
    boolean: boolean;
    bigint: bigint;
    function: Function;
    symbol: symbol;
    object: object | null;
    undefined: undefined;
};
export declare type TypeGuard<T> = (x: any) => x is T;
/**
 * A matcher for a type, which is either a single primitive name, a list of primitive names, or a type guard function
 */
export declare type Matcher<P extends PrimitiveName = PrimitiveName, T = any> = P | P[] | TypeGuard<T>;
declare type Flatten<T> = T extends Array<infer E> ? E : T;
declare type MatchedType<T extends Matcher> = T extends TypeGuard<infer E> ? E : Primitive<Extract<Flatten<T>, PrimitiveName>>;
export declare type Primitive<K extends keyof Primitives = keyof Primitives> = Primitives[K];
export declare type PrimitiveName<V extends Primitive = Primitive> = V extends string ? 'string' : V extends number ? 'number' : V extends boolean ? 'boolean' : V extends bigint ? 'bigint' : V extends Function ? 'function' : V extends symbol ? 'symbol' : V extends object | null ? 'object' : V extends undefined ? 'undefined' : never;
export declare function guard<T>(f: (x: any) => boolean): TypeGuard<T>;
/**
 * Return a type guard function checking whether a value is the type defined by the matcher
 * @param matcher
 */
export declare function is<P extends PrimitiveName, T extends Primitives[P]>(matcher: Matcher<P, T>): TypeGuard<T>;
/**
 * Return a type guard function checking whether a value is an array where each element matches the matcher
 * @param matcher
 */
export declare function isArray<P extends PrimitiveName, T extends Primitives[P]>(matcher: Matcher<P, T>): TypeGuard<T[]>;
/**
 * Return a type guard function checking whether a value is an object with the entries defined by the given map of property names to matchers
 * @param matchObj
 */
export declare function isObject<M extends Record<any, Matcher>>(matchObj: M): TypeGuard<{
    [K in keyof M]: MatchedType<M[K]>;
}>;
/**
 * Return a type guard function checking whether a value equals one of the given values
 * @param values
 */
export declare function isIn<T>(values: T[]): TypeGuard<T>;
export {};
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