DelimiterCasedPropertiesDeep: Improve array handling (#744)

sindresorhus · Nov 13, 2023 · 59411c8 · 59411c8
1 parent 8fa831e
commit 59411c8
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Showing 2 changed files with 56 additions and 9 deletions.
diff --git a/source/delimiter-cased-properties-deep.d.ts b/source/delimiter-cased-properties-deep.d.ts
@@ -1,4 +1,5 @@
 import type {DelimiterCase} from './delimiter-case';
+import type {UnknownArray} from './unknown-array';
 
 /**
 Convert object properties to delimiter case recursively.
@@ -49,12 +50,34 @@ export type DelimiterCasedPropertiesDeep<
 	Delimiter extends string,
 > = Value extends Function | Date | RegExp
 	? Value
-	: Value extends Array<infer U>
-		? Array<DelimiterCasedPropertiesDeep<U, Delimiter>>
-		: Value extends Set<infer U>
-			? Set<DelimiterCasedPropertiesDeep<U, Delimiter>> : {
-				[K in keyof Value as DelimiterCase<
-				K,
-				Delimiter
-				>]: DelimiterCasedPropertiesDeep<Value[K], Delimiter>;
-			};
+	: Value extends string
+		? DelimiterCase<Value, Delimiter>
+		: Value extends UnknownArray
+			? DelimiterCasedPropertiesArrayDeep<Value, Delimiter>
+			: Value extends Set<infer U>
+				? Set<DelimiterCasedPropertiesDeep<U, Delimiter>> : {
+					[K in keyof Value as DelimiterCase<
+					K,
+					Delimiter
+					>]: DelimiterCasedPropertiesDeep<Value[K], Delimiter>;
+				};
+
+type DelimiterCasedPropertiesArrayDeep<Value extends UnknownArray, Delimiter extends string> =
+	Value extends []
+		? []
+		// Tailing spread array
+		:	Value extends [infer U, ...infer V]
+			? [DelimiterCasedPropertiesDeep<U, Delimiter>, ...DelimiterCasedPropertiesDeep<V, Delimiter>]
+			: Value extends readonly [infer U, ...infer V]
+				? readonly [DelimiterCasedPropertiesDeep<U, Delimiter>, ...DelimiterCasedPropertiesDeep<V, Delimiter>]
+				// Leading spread array
+				: Value extends readonly [...infer U, infer V]
+					? [...DelimiterCasedPropertiesDeep<U, Delimiter>, DelimiterCasedPropertiesDeep<V, Delimiter>]
+					: Value extends readonly [...infer U, infer V]
+						? readonly [...DelimiterCasedPropertiesDeep<U, Delimiter>, DelimiterCasedPropertiesDeep<V, Delimiter>]
+						// Array
+						: Value extends Array<infer U>
+							? Array<DelimiterCasedPropertiesDeep<U, Delimiter>>
+							: Value extends ReadonlyArray<infer U>
+								? ReadonlyArray<DelimiterCasedPropertiesDeep<U, Delimiter>>
+								: never;
diff --git a/test-d/delimiter-cased-properties-deep.ts b/test-d/delimiter-cased-properties-deep.ts
@@ -46,3 +46,27 @@ const result: DelimiterCasedPropertiesDeep<UserWithFriends, '-'> = {
 	],
 };
 expectType<DelimiterCasedPropertiesDeep<UserWithFriends, '-'>>(result);
+
+// Test object key properties
+declare const key: DelimiterCasedPropertiesDeep<{readonly userId?: number}, '-'>;
+expectType<{readonly 'user-id'?: number}>(key);
+
+/** Test Array */
+// Test for tuple
+declare const tuple: DelimiterCasedPropertiesDeep<['userId', 'userName'], '-'>;
+expectType<['user-id', 'user-name']>(tuple);
+// Test for readonly
+declare const readonlyTuple: DelimiterCasedPropertiesDeep<readonly ['userId', 'userName'], '-'>;
+expectType<readonly ['user-id', 'user-name']>(readonlyTuple);
+// Test for array
+declare const array: DelimiterCasedPropertiesDeep<Array<'userId'>, '-'>;
+expectType<Array<'user-id'>>(array);
+// Test for readonly array
+declare const readonlyArray: DelimiterCasedPropertiesDeep<ReadonlyArray<'userId'>, '-'>;
+expectType<ReadonlyArray<'user-id'>>(readonlyArray);
+// Test for tailing spread array
+declare const tailingSpreadArray: DelimiterCasedPropertiesDeep<['userId', 'userName', ...Array<'userAge'>], '-'>;
+expectType<['user-id', 'user-name', ...Array<'user-age'>]>(tailingSpreadArray);
+// Test for leading spread array
+declare const leadingSpreadArray: DelimiterCasedPropertiesDeep<[...Array<'userId'>, 'userName', 'userAge'], '-'>;
+expectType<[...Array<'user-id'>, 'user-name', 'user-age']>(leadingSpreadArray);