feat: IsStrictObject<T>

.changeset/lovely-horses-press.md

@@ -0,0 +1,5 @@
+---
+"type-plus": minor
+---
+
+Add `IsStrictObject<T>` type.

type-plus/ts/equal/equal.ts

@@ -4,6 +4,7 @@ import type { IsObject } from '../object/object_type.js'
 import type { Properties } from '../object/properties.js'
 import type { And, Or } from '../predicates/logical.js'
 import type { IsSymbol } from '../symbol/symbol_type.js'
+import type { IdentityEqual } from './identity_equal.js'
 
 type BothNever<A, B, Both, One, None> = And<
 	IsNever<A>,
@@ -14,14 +15,6 @@ type BothNever<A, B, Both, One, None> = And<
 
 type BothAny<A, B, Both, One, None> = And<IsAny<A>, IsAny<B>, Both, Or<IsAny<A>, IsAny<B>, One, None>>
 
-type IdentityEqual<A, B, Then, Else> = (<_>() => _ extends (A & _) | _ ? 1 : 2) extends <_>() => _ extends
-	| (B & _)
-	| _
-	? 1
-	: 2
-	? Then
-	: Else
-
 /**
  * Checks `A` and `B` are equal.
  *

type-plus/ts/equal/identity_equal.ts

@@ -0,0 +1,9 @@
+
+/**
+ * This is a common equal check.
+ * It is good for some basic cases, but not for all.
+ */
+export type IdentityEqual<A, B, Then, Else> =
+	(<_>() => _ extends (A & _) | _ ? 1 : 2) extends (<_>() => _ extends | (B & _) | _ ? 1 : 2)
+	? Then
+	: Else

type-plus/ts/index.ts

@@ -83,6 +83,7 @@ export type {
 export type { IsNotPositive, IsPositive, NonPositive, Positive } from './numeric/positive.js'
 export type { Required, RequiredExcept, RequiredPick } from './object/Required.js'
 export * from './object/index.js'
+export type * from './object/is_strict_object.js'
 export * as ObjectPlus from './object/object_plus.js'
 export type { IsNotObject, IsObject, NotObjectType, ObjectType } from './object/object_type.js'
 export * from './predicates/index.js'
@@ -123,3 +124,4 @@ export * from './unpartial.js'
 export * from './utils/index.js'
 export type { TypePlusOptions } from './utils/options.js'
 export type { IsNotVoid, IsVoid, NotVoidType, VoidType } from './void/void_type.js'
+

type-plus/ts/mix_types/box.ts

@@ -2,7 +2,7 @@ import type { IsBigint } from '../bigint/bigint_type.js'
 import type { IsBoolean } from '../boolean/boolean_type.js'
 import type { IsFunction } from '../function/function_type.js'
 import type { IsNumber } from '../number/number_type.js'
-import type { IsStrictObject } from '../object/object_type.js'
+import type { IsStrictObject } from '../object/is_strict_object.js'
 import type { IsString } from '../string/string_type.js'
 import type { IsSymbol } from '../symbol/symbol_type.js'
 

type-plus/ts/object/is_strict_object.spec.ts

@@ -0,0 +1,21 @@
+import { it } from 'node:test'
+import { testType, type IsStrictObject } from '../index.js'
+
+it('returns false for special types', () => {
+	testType.equal<IsStrictObject<any>, false>(true)
+	testType.equal<IsStrictObject<unknown>, false>(true)
+	testType.equal<IsStrictObject<never>, false>(true)
+	testType.equal<IsStrictObject<void>, false>(true)
+})
+
+it('returns false for object literal', () => {
+	testType.equal<IsStrictObject<{ a: number }>, false>(true)
+})
+
+it('returns false for empty object literal', () => {
+	testType.equal<IsStrictObject<{}>, false>(true)
+})
+
+it('returns true for object', () => {
+	testType.equal<IsStrictObject<object>, true>(true)
+})

type-plus/ts/object/is_strict_object.ts

@@ -0,0 +1,14 @@
+import type { IdentityEqual } from '../equal/identity_equal.js'
+import type { IsNever } from '../never/never_type.js'
+import type { IsObject } from './object_type.js'
+
+/**
+ * 🎭 *validate*
+ *
+ * Validate that `T` is strictly the `object` type.
+ */
+export type IsStrictObject<T, Then = true, Else = false> = IsObject<
+	T,
+	IdentityEqual<T, {}, Else, IsNever<keyof T, Then, Else>>,
+	Else
+>