typia/lib/SnakeCase.d.mts

Superfast runtime validators with only one line

import { Equal } from "./typings/Equal";
import { NativeClass } from "./typings/NativeClass";
import { ValueOf } from "./typings/ValueOf";
/**
 * Snake case type.
 *
 * `SnakeCase` type is a type that all keys of an object are converted to snake
 * case.
 *
 * It also erases every method property like {@link Resolved} type.
 *
 * @author Jeongho Nam - https://github.com/samchon
 * @template T Target type to be snake cased
 */
export type SnakeCase<T> = Equal<T, SnakageMain<T>> extends true ? T : SnakageMain<T>;
type SnakageMain<T> = T extends [never] ? never : T extends {
    valueOf(): boolean | bigint | number | string;
} ? ValueOf<T> : T extends Function ? never : T extends object ? SnakageObject<T> : T;
type SnakageObject<T extends object> = T extends Array<infer U> ? IsTuple<T> extends true ? SnakageTuple<T> : SnakageMain<U>[] : T extends Set<infer U> ? Set<SnakageMain<U>> : T extends Map<infer K, infer V> ? Map<SnakageMain<K>, SnakageMain<V>> : T extends WeakSet<any> | WeakMap<any, any> ? never : T extends NativeClass ? T : {
    [Key in keyof T as SnakageString<Key & string>]: SnakageMain<T[Key]>;
};
type IsTuple<T extends readonly any[] | {
    length: number;
}> = [T] extends [
    never
] ? false : T extends readonly any[] ? number extends T["length"] ? false : true : false;
type SnakageTuple<T extends readonly any[]> = T extends [] ? [] : T extends [infer F] ? [SnakageMain<F>] : T extends [infer F, ...infer Rest extends readonly any[]] ? [SnakageMain<F>, ...SnakageTuple<Rest>] : T extends [(infer F)?] ? [SnakageMain<F>?] : T extends [(infer F)?, ...infer Rest extends readonly any[]] ? [SnakageMain<F>?, ...SnakageTuple<Rest>] : [];
type SnakageString<Key extends string> = Key extends `${infer _}` ? SnakageStringRepeatedly<Key, ""> : Key;
type SnakageStringRepeatedly<S extends string, Previous extends string> = S extends `${infer First}${infer Second}${infer Rest}` ? `${Underscore<Previous, First>}${Lowercase<First>}${Underscore<First, Second>}${Lowercase<Second>}${SnakageStringRepeatedly<Rest, Second>}` : S extends `${infer First}` ? `${Underscore<Previous, First>}${Lowercase<First>}` : "";
type Underscore<First extends string, Second extends string> = First extends UpperAlphabetic | "" | "_" ? "" : Second extends UpperAlphabetic ? "_" : "";
type UpperAlphabetic = "A" | "B" | "C" | "D" | "E" | "F" | "G" | "H" | "I" | "J" | "K" | "L" | "M" | "N" | "O" | "P" | "Q" | "R" | "S" | "T" | "U" | "V" | "W" | "X" | "Y" | "Z";
export {};