type-fest/source/internal.d.ts

import type {Primitive} from './primitive';
import type {Simplify} from './simplify';
import type {Trim} from './trim';
import type {IsAny} from './is-any';
import type {UnknownRecord} from './unknown-record';

// TODO: Remove for v5.
export type {UnknownRecord} from './unknown-record';

/**
Infer the length of the given array `<T>`.

@link https://itnext.io/implementing-arithmetic-within-typescripts-type-system-a1ef140a6f6f
*/
type TupleLength<T extends readonly unknown[]> = T extends {readonly length: infer L} ? L : never;

/**
Create a tuple type of the given length `<L>` and fill it with the given type `<Fill>`.

If `<Fill>` is not provided, it will default to `unknown`.

@link https://itnext.io/implementing-arithmetic-within-typescripts-type-system-a1ef140a6f6f
*/
export type BuildTuple<L extends number, Fill = unknown, T extends readonly unknown[] = []> = T extends {readonly length: L}
	? T
	: BuildTuple<L, Fill, [...T, Fill]>;

/**
Create an object type with the given key `<Key>` and value `<Value>`.

It will copy the prefix and optional status of the same key from the given object `CopiedFrom` into the result.

@example
```
type A = BuildObject<'a', string>;
//=> {a: string}

// Copy `readonly` and `?` from the key `a` of `{readonly a?: any}`
type B = BuildObject<'a', string, {readonly a?: any}>;
//=> {readonly a?: string}
```
*/
export type BuildObject<Key extends PropertyKey, Value, CopiedFrom extends object = {}> =
	Key extends keyof CopiedFrom
		? Pick<{[_ in keyof CopiedFrom]: Value}, Key>
		: Key extends `${infer NumberKey extends number}`
			? NumberKey extends keyof CopiedFrom
				? Pick<{[_ in keyof CopiedFrom]: Value}, NumberKey>
				: {[_ in Key]: Value}
			: {[_ in Key]: Value};

/**
Return a string representation of the given string or number.

Note: This type is not the return type of the `.toString()` function.
*/
export type ToString<T> = T extends string | number ? `${T}` : never;

/**
Create a tuple of length `A` and a tuple composed of two other tuples,
the inferred tuple `U` and a tuple of length `B`, then extracts the length of tuple `U`.

@link https://itnext.io/implementing-arithmetic-within-typescripts-type-system-a1ef140a6f6f
*/
export type Subtract<A extends number, B extends number> = BuildTuple<A> extends [...(infer U), ...BuildTuple<B>]
	? TupleLength<U>
	: never;

/**
Matches any primitive, `Date`, or `RegExp` value.
*/
export type BuiltIns = Primitive | Date | RegExp;

/**
Matches non-recursive types.
*/
export type NonRecursiveType = BuiltIns | Function | (new (...args: any[]) => unknown);

export type UpperCaseCharacters = '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 type StringDigit = '0' | '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9';

export type Whitespace =
	| '\u{9}' // '\t'
	| '\u{A}' // '\n'
	| '\u{B}' // '\v'
	| '\u{C}' // '\f'
	| '\u{D}' // '\r'
	| '\u{20}' // ' '
	| '\u{85}'
	| '\u{A0}'
	| '\u{1680}'
	| '\u{2000}'
	| '\u{2001}'
	| '\u{2002}'
	| '\u{2003}'
	| '\u{2004}'
	| '\u{2005}'
	| '\u{2006}'
	| '\u{2007}'
	| '\u{2008}'
	| '\u{2009}'
	| '\u{200A}'
	| '\u{2028}'
	| '\u{2029}'
	| '\u{202F}'
	| '\u{205F}'
	| '\u{3000}'
	| '\u{FEFF}';

export type WordSeparators = '-' | '_' | Whitespace;

/**
Matches any unknown array or tuple.
*/
export type UnknownArrayOrTuple = readonly [...unknown[]];

/**
Matches any non empty tuple.
*/
export type NonEmptyTuple = readonly [unknown, ...unknown[]];

/**
Returns a boolean for whether the two given types extends the base type.
*/
export type IsBothExtends<BaseType, FirstType, SecondType> = FirstType extends BaseType
	? SecondType extends BaseType
		? true
		: false
	: false;

/**
Extracts the type of the first element of an array or tuple.
*/
export type FirstArrayElement<TArray extends UnknownArrayOrTuple> = TArray extends readonly [infer THead, ...unknown[]]
	? THead
	: never;

/**
Extracts the type of an array or tuple minus the first element.
*/
export type ArrayTail<TArray extends UnknownArrayOrTuple> = TArray extends readonly [unknown, ...infer TTail] ? TTail : [];

/**
Extract the element of an array that also works for array union.

Returns `never` if T is not an array.

It creates a type-safe way to access the element type of `unknown` type.
*/
export type ArrayElement<T> = T extends readonly unknown[] ? T[0] : never;

/**
Extract the object field type if T is an object and K is a key of T, return `never` otherwise.

It creates a type-safe way to access the member type of `unknown` type.
*/
export type ObjectValue<T, K> =
	K extends keyof T
		? T[K]
		: ToString<K> extends keyof T
			? T[ToString<K>]
			: K extends `${infer NumberK extends number}`
				? NumberK extends keyof T
					? T[NumberK]
					: never
				: never;

/**
Returns a boolean for whether the string is lowercased.
*/
export type IsLowerCase<T extends string> = T extends Lowercase<T> ? true : false;

/**
Returns a boolean for whether the string is uppercased.
*/
export type IsUpperCase<T extends string> = T extends Uppercase<T> ? true : false;

/**
Returns a boolean for whether a string is whitespace.
*/
export type IsWhitespace<T extends string> = T extends Whitespace
	? true
	: T extends `${Whitespace}${infer Rest}`
		? IsWhitespace<Rest>
		: false;

/**
Returns a boolean for whether the string is numeric.

This type is a workaround for [Microsoft/TypeScript#46109](https://github.com/microsoft/TypeScript/issues/46109#issuecomment-930307987).
*/
export type IsNumeric<T extends string> = T extends `${number}`
	? Trim<T> extends T
		? true
		: false
	: false;

/**
For an object T, if it has any properties that are a union with `undefined`, make those into optional properties instead.

@example
```
type User = {
	firstName: string;
	lastName: string | undefined;
};

type OptionalizedUser = UndefinedToOptional<User>;
//=> {
// 	firstName: string;
// 	lastName?: string;
// }
```
*/
export type UndefinedToOptional<T extends object> = Simplify<
{
	// Property is not a union with `undefined`, keep it as-is.
	[Key in keyof Pick<T, FilterDefinedKeys<T>>]: T[Key];
} & {
	// Property _is_ a union with defined value. Set as optional (via `?`) and remove `undefined` from the union.
	[Key in keyof Pick<T, FilterOptionalKeys<T>>]?: Exclude<T[Key], undefined>;
}
>;

// Returns `never` if the key or property is not jsonable without testing whether the property is required or optional otherwise return the key.
type BaseKeyFilter<Type, Key extends keyof Type> = Key extends symbol
	? never
	: Type[Key] extends symbol
		? never
		/*
		To prevent a problem where an object with only a `name` property is incorrectly treated as assignable to a function, we first check if the property is a record.
		This check is necessary, because without it, if we don't verify whether the property is a record, an object with a type of `{name: any}` would return `never` due to its potential assignability to a function.
		See: https://github.com/sindresorhus/type-fest/issues/657
		*/
		: Type[Key] extends Record<string, unknown>
			? Key
			: [(...arguments_: any[]) => any] extends [Type[Key]]
				? never
				: Key;

/**
Returns the required keys.
*/
type FilterDefinedKeys<T extends object> = Exclude<
{
	[Key in keyof T]: IsAny<T[Key]> extends true
		? Key
		: undefined extends T[Key]
			? never
			: T[Key] extends undefined
				? never
				: BaseKeyFilter<T, Key>;
}[keyof T],
undefined
>;

/**
Returns the optional keys.
*/
type FilterOptionalKeys<T extends object> = Exclude<
{
	[Key in keyof T]: IsAny<T[Key]> extends true
		? never
		: undefined extends T[Key]
			? T[Key] extends undefined
				? never
				: BaseKeyFilter<T, Key>
			: never;
}[keyof T],
undefined
>;

/**
Test if the given function has multiple call signatures.

Needed to handle the case of a single call signature with properties.

Multiple call signatures cannot currently be supported due to a TypeScript limitation.
@see https://github.com/microsoft/TypeScript/issues/29732
*/
export type HasMultipleCallSignatures<T extends (...arguments_: any[]) => unknown> =
	T extends {(...arguments_: infer A): unknown; (...arguments_: any[]): unknown}
		? unknown[] extends A
			? false
			: true
		: false;

/**
Returns a boolean for whether the given `boolean` is not `false`.
*/
export type IsNotFalse<T extends boolean> = [T] extends [false] ? false : true;

/**
Returns a boolean for whether the given type is `null`.
*/
export type IsNull<T> = [T] extends [null] ? true : false;

/**
Disallows any of the given keys.
*/
export type RequireNone<KeysType extends PropertyKey> = Partial<Record<KeysType, never>>;

/**
Returns a boolean for whether the given type is primitive value or primitive type.

@example
```
IsPrimitive<'string'>
//=> true

IsPrimitive<string>
//=> true

IsPrimitive<Object>
//=> false
```
*/
export type IsPrimitive<T> = [T] extends [Primitive] ? true : false;