Support serializing and deserializing nested custom types (#118)

Sources/Defaults/Utilities.swift

@@ -167,18 +167,20 @@ extension Defaults.Serializable {
 	return Value.toValue(anyObject)
 	```
 	*/
-	static func toValue(_ anyObject: Any) -> Self? {
-		// Return directly if `anyObject` can cast to Value, since it means `Value` is a natively supported type.
+	static func toValue<T: Defaults.Serializable>(_ anyObject: Any, type: T.Type = Self.self) -> T? {
 		if
-			isNativelySupportedType,
-			let anyObject = anyObject as? Self
+			T.isNativelySupportedType,
+			let anyObject = anyObject as? T
 		{
 			return anyObject
-		} else if let value = bridge.deserialize(anyObject as? Serializable) {
-			return value as? Self
 		}
 
-		return nil
+		guard let nextType = T.Serializable.self as? any Defaults.Serializable.Type else {
+			// This is a special case for the types which do not conform to `Defaults.Serializable` (for example, `Any`).
+			return T.bridge.deserialize(anyObject as? T.Serializable) as? T
+		}
+
+		return T.bridge.deserialize(toValue(anyObject, type: nextType) as? T.Serializable) as? T
 	}
 
 	/**
@@ -190,14 +192,20 @@ extension Defaults.Serializable {
 	set(Value.toSerialize(value), forKey: key)
 	```
 	*/
-	static func toSerializable(_ value: Self) -> Any? {
-		// Return directly if `Self` is a natively supported type, since it does not need serialization.
-		if isNativelySupportedType {
+	static func toSerializable<T: Defaults.Serializable>(_ value: T) -> Any? {
+		if T.isNativelySupportedType {
 			return value
-		} else if let serialized = bridge.serialize(value as? Value) {
+		}
+
+		guard let serialized = T.bridge.serialize(value as? T.Value) else {
+			return nil
+		}
+
+		guard let next = serialized as? any Defaults.Serializable else {
+			// This is a special case for the types which do not conform to `Defaults.Serializable` (for example, `Any`).
 			return serialized
 		}
 
-		return nil
+		return toSerializable(next)
 	}
 }

Tests/DefaultsTests/DefaultsCustomBridgeTests.swift

@@ -38,13 +38,57 @@ public final class DefaultsUserBridge: Defaults.Bridge {
 
 private let fixtureCustomBridge = User(username: "hank121314", password: "123456")
 
+struct PlainHourMinuteTimeRange: Hashable, Codable {
+	var start: PlainHourMinuteTime
+	var end: PlainHourMinuteTime
+}
+
+extension PlainHourMinuteTimeRange: Defaults.Serializable {
+	struct Bridge: Defaults.Bridge {
+		typealias Value = PlainHourMinuteTimeRange
+		typealias Serializable = [PlainHourMinuteTime]
+
+		public func serialize(_ value: Value?) -> Serializable? {
+			guard let value = value else {
+				return nil
+			}
+
+			return [value.start, value.end]
+		}
+
+		public func deserialize(_ object: Serializable?) -> Value? {
+			guard
+				let array = object,
+				let start = array[safe: 0],
+				let end = array[safe: 1]
+			else {
+				return nil
+			}
+
+			return .init(start: start, end: end)
+		}
+	}
+
+	static let bridge = Bridge()
+}
+
+struct PlainHourMinuteTime: Hashable, Codable, Defaults.Serializable {
+	var hour: Int
+	var minute: Int
+}
+
+extension Collection {
+	subscript(safe index: Index) -> Element? {
+		indices.contains(index) ? self[index] : nil
+	}
+}
+
 extension Defaults.Keys {
 	fileprivate static let customBridge = Key<User>("customBridge", default: fixtureCustomBridge)
 	fileprivate static let customBridgeArray = Key<[User]>("array_customBridge", default: [fixtureCustomBridge])
 	fileprivate static let customBridgeDictionary = Key<[String: User]>("dictionary_customBridge", default: ["0": fixtureCustomBridge])
 }
 
-
 final class DefaultsCustomBridge: XCTestCase {
 	override func setUp() {
 		super.setUp()
@@ -148,6 +192,35 @@ final class DefaultsCustomBridge: XCTestCase {
 		XCTAssertEqual(Defaults[key]["0"]?[1], fixtureCustomBridge)
 	}
 
+	func testRecursiveKey() {
+		let start = PlainHourMinuteTime(hour: 1, minute: 0)
+		let end = PlainHourMinuteTime(hour: 2, minute: 0)
+		let range = PlainHourMinuteTimeRange(start: start, end: end)
+		let key = Defaults.Key<PlainHourMinuteTimeRange>("independentCustomBridgeRecursiveKey", default: range)
+		XCTAssertEqual(Defaults[key].start.hour, range.start.hour)
+		XCTAssertEqual(Defaults[key].start.minute, range.start.minute)
+		XCTAssertEqual(Defaults[key].end.hour, range.end.hour)
+		XCTAssertEqual(Defaults[key].end.minute, range.end.minute)
+		guard let rawValue = UserDefaults.standard.array(forKey: key.name) as? [String] else {
+			XCTFail("rawValue should not be nil")
+			return
+		}
+		XCTAssertEqual(rawValue, [#"{"minute":0,"hour":1}"#, #"{"minute":0,"hour":2}"#])
+		let next_start = PlainHourMinuteTime(hour: 3, minute: 58)
+		let next_end = PlainHourMinuteTime(hour: 4, minute: 59)
+		let next_range = PlainHourMinuteTimeRange(start: next_start, end: next_end)
+		Defaults[key] = next_range
+		XCTAssertEqual(Defaults[key].start.hour, next_range.start.hour)
+		XCTAssertEqual(Defaults[key].start.minute, next_range.start.minute)
+		XCTAssertEqual(Defaults[key].end.hour, next_range.end.hour)
+		XCTAssertEqual(Defaults[key].end.minute, next_range.end.minute)
+		guard let nextRawValue = UserDefaults.standard.array(forKey: key.name) as? [String] else {
+			XCTFail("nextRawValue should not be nil")
+			return
+		}
+		XCTAssertEqual(nextRawValue, [#"{"minute":58,"hour":3}"#, #"{"minute":59,"hour":4}"#])
+	}
+
 	func testType() {
 		XCTAssertEqual(Defaults[.customBridge], fixtureCustomBridge)
 		let newUser = User(username: "sindresorhus", password: "123456789")