type-plus/ts/object/left_join.ts

Provides additional types for TypeScript.

import type { IsEqual } from '../equal/equal.js'
import type { AnyRecord } from './AnyRecord.js'
import type { IsDisjoint } from './IsDisjoint.js'
import type { KeysWithDiffType } from './KeysWithDiffType.js'
import type { Properties } from './properties.js'

export type ANotB<A extends AnyRecord, B extends AnyRecord> = IsEqual<A, B> extends true
	? never
	: IsDisjoint<A, B> extends true
	? A
	: { [k in Exclude<keyof A, keyof B> | KeysWithDiffType<A, B>]: A[k] }

export type BNotA<A extends AnyRecord, B extends AnyRecord> = ANotB<B, A>

export type LeftJoin<A extends AnyRecord, B extends AnyRecord> = IsEqual<A, B> extends true
	? A
	: IsDisjoint<A, B> extends true
	? A & B
	: Properties<{ [k in Exclude<keyof A, keyof B>]: A[k] } & { [k in keyof B]: B[k] }>