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/*
This source file is part of the Swift.org open source project
Copyright (c) 2014 - 2020 Apple Inc. and the Swift project authors
Licensed under Apache License v2.0 with Runtime Library Exception
See http://swift.org/LICENSE.txt for license information
See http://swift.org/CONTRIBUTORS.txt for Swift project authors
*/
/// Allows encoding and decoding known polymorphic types.
public protocol PolymorphicCodableProtocol: Codable {
static var implementations: [PolymorphicCodableProtocol.Type] { get }
}
@propertyWrapper
public struct PolymorphicCodable<T: PolymorphicCodableProtocol>: Codable {
public let value: T
public init(wrappedValue value: T) {
self.value = value
}
public var wrappedValue: T {
return value
}
public func encode(to encoder: Encoder) throws {
var container = encoder.unkeyedContainer()
try container.encode(String(reflecting: type(of: value)))
try container.encode(value)
}
public init(from decoder: Decoder) throws {
var container = try decoder.unkeyedContainer()
let typeCode = try container.decode(String.self)
guard let klass = T.implementations.first(where: { String(reflecting: $0) == typeCode }) else {
throw DecodingError.dataCorruptedError(in: container, debugDescription: "Unexpected Codable type code for concrete '\(type(of: T.self))': \(typeCode)")
}
self.value = try klass.init(from: container.superDecoder()) as! T
}
}
extension PolymorphicCodable: Sendable where T: Sendable {}
@propertyWrapper
public struct PolymorphicCodableArray<T: PolymorphicCodableProtocol>: Codable {
public let value: [PolymorphicCodable<T>]
public init(wrappedValue value: [T]) {
self.value = value.map{ PolymorphicCodable(wrappedValue: $0) }
}
public var wrappedValue: [T] {
return value.map{ $0.value }
}
}
extension PolymorphicCodableArray: Sendable where T: Sendable {}
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