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//
// Decoder.swift
// ObjectEncoder
//
// Created by Norio Nomura on 10/21/17.
// Copyright (c) 2017 ObjectEncoder. All rights reserved.
//
#if !_runtime(_ObjC)
import CoreFoundation
#endif
import Foundation
public struct ObjectDecoder {
public init() {}
public func decode<T>(_ type: T.Type = T.self,
from object: Any,
userInfo: [CodingUserInfoKey: Any] = [:]) throws -> T where T: Decodable {
do {
return try ObjectDecoder.Decoder(object, options, userInfo).singleValueContainer().decode(type)
} catch let error as DecodingError {
throw error
} catch {
throw _dataCorrupted(at: [], "The given data was not valid Object.", error)
}
}
public struct DecodingStrategy<T: Decodable> {
public typealias Closure = (Decoder) throws -> T
public init(closure: @escaping Closure) { self.closure = closure }
fileprivate let closure: Closure
}
public struct DecodingStrategies {
var strategies = [ObjectIdentifier: Any]()
public subscript<T>(type: T.Type) -> DecodingStrategy<T>? {
get { return strategies[ObjectIdentifier(type)] as? DecodingStrategy<T> }
set { strategies[ObjectIdentifier(type)] = newValue }
}
}
/// The strategis to use for decoding values.
public var decodingStrategies: DecodingStrategies {
get { return options.decodingStrategies }
set { options.decodingStrategies = newValue }
}
// MARK: -
fileprivate struct Options {
fileprivate var decodingStrategies = DecodingStrategies()
}
fileprivate var options = Options()
}
extension ObjectDecoder {
public struct Decoder: Swift.Decoder {
public let object: Any
fileprivate typealias Options = ObjectDecoder.Options
private let options: Options
fileprivate init(_ object: Any,
_ options: Options,
_ userInfo: [CodingUserInfoKey: Any],
_ codingPath: [CodingKey] = []) {
self.object = object
self.options = options
self.userInfo = userInfo
self.codingPath = codingPath
}
// MARK: - Swift.Decoder properties
public let codingPath: [CodingKey]
public let userInfo: [CodingUserInfoKey: Any]
}
}
extension ObjectDecoder.Decoder {
// MARK: - Swift.Decoder Methods
public func container<Key>(keyedBy type: Key.Type) throws -> KeyedDecodingContainer<Key> {
return .init(_KeyedDecodingContainer<Key>(decoder: self, wrapping: try cast()))
}
public func unkeyedContainer() throws -> UnkeyedDecodingContainer {
return _UnkeyedDecodingContainer(decoder: self, wrapping: try cast())
}
public func singleValueContainer() throws -> SingleValueDecodingContainer { return self }
// MARK: -
private func applyStrategy<T: Decodable>(_ type: T.Type) throws -> T? {
if let strategy = options.decodingStrategies[type] ?? options.decodingStrategies[T.self] {
return try strategy.closure(self)
}
return nil
}
private func cast<T>() throws -> T {
guard let value = object as? T else {
throw _typeMismatch(at: codingPath, expectation: T.self, reality: object)
}
return value
}
// - SeeAlso: https://github.com/apple/swift/pull/11885
private func cast<T: ShouldNotBeDecodedFromBool>() throws -> T {
if let number = object as? NSNumber {
guard number !== kCFBooleanTrue, number !== kCFBooleanFalse else {
throw _typeMismatch(at: codingPath, expectation: NSNumber.self, reality: object)
}
guard let value = T.init(exactly: number) else {
throw _dataCorrupted(at: codingPath, "Parsed number <\(number)> does not fit in \(T.self).")
}
return value
} else if let value = object as? T {
return value
}
throw _typeMismatch(at: codingPath, expectation: T.self, reality: object)
}
private func cast() throws -> Bool {
if let number = object as? NSNumber {
if number === kCFBooleanTrue {
return true
} else if number === kCFBooleanFalse {
return false
}
throw _typeMismatch(at: codingPath, expectation: type(of: kCFBooleanTrue.self), reality: object)
} else if let bool = object as? Bool {
return bool
}
throw _typeMismatch(at: codingPath, expectation: Bool.self, reality: object)
}
/// create a new `_Decoder` instance referencing `object` as `key` inheriting `userInfo`
fileprivate func decoder(referencing object: Any, `as` key: CodingKey) -> ObjectDecoder.Decoder {
return .init(object, options, userInfo, codingPath + [key])
}
}
private struct _KeyedDecodingContainer<Key: CodingKey>: KeyedDecodingContainerProtocol {
private let decoder: ObjectDecoder.Decoder
private let dictionary: [String: Any]
init(decoder: ObjectDecoder.Decoder, wrapping dictionary: [String: Any]) {
self.decoder = decoder
self.dictionary = dictionary
}
// MARK: - Swift.KeyedDecodingContainerProtocol Methods
var codingPath: [CodingKey] { return decoder.codingPath }
var allKeys: [Key] {
#if swift(>=4.1)
return dictionary.keys.compactMap(Key.init)
#else
return dictionary.keys.flatMap(Key.init)
#endif
}
func contains(_ key: Key) -> Bool { return dictionary[key.stringValue] != nil }
func decodeNil(forKey key: Key) throws -> Bool {
return try object(for: key) is NSNull
}
func decode(_ type: Bool.Type, forKey key: Key) throws -> Bool { return try decoder(for: key).decode(type) }
func decode(_ type: String.Type, forKey key: Key) throws -> String { return try decoder(for: key).decode(type) }
func decode<T>(_ type: T.Type, forKey key: Key) throws -> T where T: ShouldNotBeDecodedFromBool {
return try decoder(for: key).decode(type)
}
func decode<T>(_ type: T.Type, forKey key: Key) throws -> T where T: Decodable {
return try decoder(for: key).decode(type)
}
func nestedContainer<NestedKey>(keyedBy type: NestedKey.Type,
forKey key: Key) throws -> KeyedDecodingContainer<NestedKey> {
return try decoder(for: key).container(keyedBy: type)
}
func nestedUnkeyedContainer(forKey key: Key) throws -> UnkeyedDecodingContainer {
return try decoder(for: key).unkeyedContainer()
}
func superDecoder() throws -> Decoder { return try decoder(for: _ObjectCodingKey.super) }
func superDecoder(forKey key: Key) throws -> Decoder { return try decoder(for: key) }
// MARK: -
private func object(for key: CodingKey) throws -> Any {
guard let object = dictionary[key.stringValue] else {
throw _keyNotFound(at: codingPath, key, "No value associated with key \(key) (\"\(key.stringValue)\").")
}
return object
}
private func decoder(for key: CodingKey) throws -> ObjectDecoder.Decoder {
return decoder.decoder(referencing: try object(for: key), as: key)
}
}
private struct _UnkeyedDecodingContainer: UnkeyedDecodingContainer {
private let decoder: ObjectDecoder.Decoder
private let array: [Any]
init(decoder: ObjectDecoder.Decoder, wrapping array: [Any]) {
self.decoder = decoder
self.array = array
self.currentIndex = 0
}
// MARK: - Swift.UnkeyedDecodingContainer Methods
var codingPath: [CodingKey] { return decoder.codingPath }
var count: Int? { return array.count }
var isAtEnd: Bool { return currentIndex >= array.count }
var currentIndex: Int
mutating func decodeNil() throws -> Bool {
try throwErrorIfAtEnd(Any?.self)
if currentObject is NSNull {
currentIndex += 1
return true
} else {
return false
}
}
mutating func decode(_ type: Bool.Type) throws -> Bool { return try currentDecoder { try $0.decode(type) } }
mutating func decode(_ type: String.Type) throws -> String { return try currentDecoder { try $0.decode(type) } }
mutating func decode<T>(_ type: T.Type) throws -> T where T: ShouldNotBeDecodedFromBool {
return try currentDecoder { try $0.decode(type) }
}
mutating func decode<T>(_ type: T.Type) throws -> T where T: Decodable {
return try currentDecoder { try $0.decode(type) }
}
mutating func nestedContainer<NestedKey>(keyedBy type: NestedKey.Type) throws -> KeyedDecodingContainer<NestedKey> {
return try currentDecoder { try $0.container(keyedBy: type) }
}
mutating func nestedUnkeyedContainer() throws -> UnkeyedDecodingContainer {
return try currentDecoder { try $0.unkeyedContainer() }
}
mutating func superDecoder() throws -> Decoder {
return try currentDecoder { $0 }
}
// MARK: -
private var currentKey: CodingKey { return _ObjectCodingKey(index: currentIndex) }
private var currentObject: Any { return array[currentIndex] }
private func throwErrorIfAtEnd<T>(_ type: T.Type) throws {
if isAtEnd { throw _valueNotFound(at: codingPath + [currentKey], type, "Unkeyed container is at end.") }
}
private mutating func currentDecoder<T>(closure: (ObjectDecoder.Decoder) throws -> T) throws -> T {
try throwErrorIfAtEnd(T.self)
let decoded: T = try closure(decoder.decoder(referencing: currentObject, as: currentKey))
currentIndex += 1
return decoded
}
}
extension ObjectDecoder.Decoder: SingleValueDecodingContainer {
// MARK: - Swift.SingleValueDecodingContainer Methods
public func decodeNil() -> Bool { return object is NSNull }
public func decode(_ type: Bool.Type) throws -> Bool { return try applyStrategy(type) ?? cast() }
public func decode(_ type: String.Type) throws -> String { return try applyStrategy(type) ?? cast() }
public func decode<T>(_ type: T.Type) throws -> T where T: ShouldNotBeDecodedFromBool {
return try applyStrategy(type) ?? cast()
}
public func decode<T>(_ type: T.Type) throws -> T where T: Decodable {
return try applyStrategy(type) ?? type.init(from: self)
}
}
// MARK: - ShouldNotBeDecodedFromBool
// https://github.com/apple/swift/pull/11885
public protocol ShouldNotBeDecodedFromBool: Decodable {
// Swift 4.0 on darwin, Swift 4.0.2 on swift-corelibs-foundation
init?(exactly number: NSNumber)
}
extension Int: ShouldNotBeDecodedFromBool {}
extension Int8: ShouldNotBeDecodedFromBool {}
extension Int16: ShouldNotBeDecodedFromBool {}
extension Int32: ShouldNotBeDecodedFromBool {}
extension Int64: ShouldNotBeDecodedFromBool {}
extension UInt: ShouldNotBeDecodedFromBool {}
extension UInt8: ShouldNotBeDecodedFromBool {}
extension UInt16: ShouldNotBeDecodedFromBool {}
extension UInt32: ShouldNotBeDecodedFromBool {}
extension UInt64: ShouldNotBeDecodedFromBool {}
extension Float: ShouldNotBeDecodedFromBool {}
extension Double: ShouldNotBeDecodedFromBool {}
// MARK: - DecodingError helpers
// swiftlint:disable:next identifier_name
func _dataCorrupted(at codingPath: [CodingKey], _ description: String, _ error: Error? = nil) -> DecodingError {
let context = DecodingError.Context(codingPath: codingPath, debugDescription: description, underlyingError: error)
return .dataCorrupted(context)
}
private func _keyNotFound(at codingPath: [CodingKey], _ key: CodingKey, _ description: String) -> DecodingError {
let context = DecodingError.Context(codingPath: codingPath, debugDescription: description)
return.keyNotFound(key, context)
}
private func _valueNotFound(at codingPath: [CodingKey], _ type: Any.Type, _ description: String) -> DecodingError {
let context = DecodingError.Context(codingPath: codingPath, debugDescription: description)
return .valueNotFound(type, context)
}
private func _typeMismatch(at codingPath: [CodingKey], expectation: Any.Type, reality: Any) -> DecodingError {
let description = "Expected to decode \(expectation) but found \(type(of: reality)) instead."
let context = DecodingError.Context(codingPath: codingPath, debugDescription: description)
return .typeMismatch(expectation, context)
}
// MARK: - ObjectDecoder.DecodingStrategy
extension ObjectDecoder {
/// The strategy to use for decoding `Data` values.
public typealias DataDecodingStrategy = DecodingStrategy<Data>
/// The strategy to use for decoding `Date` values.
public typealias DateDecodingStrategy = DecodingStrategy<Date>
/// The strategy to use for decoding `Double` values.
public typealias DoubleDecodingStrategy = DecodingStrategy<Double>
/// The strategy to use for decoding `Float` values.
public typealias FloatDecodingStrategy = DecodingStrategy<Float>
}
extension ObjectDecoder.DecodingStrategy {
/// Decode the `T` as a custom value decoded by the given closure.
public static func custom(_ closure: @escaping Closure) -> ObjectDecoder.DecodingStrategy<T> {
return .init(closure: closure)
}
}
extension ObjectDecoder.DecodingStrategy where T == Data {
/// Defer to `Data` for decoding.
public static let deferredToData: ObjectDecoder.DataDecodingStrategy? = nil
/// Decode the `Data` from a Base64-encoded string. This is the default strategy.
public static let base64 = ObjectDecoder.DataDecodingStrategy.custom { decoder in
guard let data = Data(base64Encoded: try String(from: decoder)) else {
throw _dataCorrupted(at: decoder.codingPath, "Encountered Data is not valid Base64.")
}
return data
}
}
extension ObjectDecoder.DecodingStrategy where T == Date {
/// Defer to `Date` for decoding.
public static let deferredToDate: ObjectDecoder.DateDecodingStrategy? = nil
/// Decode the `Date` as a UNIX timestamp from a `Double`.
public static let secondsSince1970 = ObjectDecoder.DateDecodingStrategy.custom { decoder in
Date(timeIntervalSince1970: try Double(from: decoder))
}
/// Decode the `Date` as UNIX millisecond timestamp from a `Double`.
public static let millisecondsSince1970 = ObjectDecoder.DateDecodingStrategy.custom { decoder in
Date(timeIntervalSince1970: try Double(from: decoder) / 1000.0)
}
/// Decode the `Date` as an ISO-8601-formatted string (in RFC 3339 format).
@available(OSX 10.12, iOS 10.0, watchOS 3.0, tvOS 10.0, *)
public static let iso8601 = ObjectDecoder.DateDecodingStrategy.custom { decoder in
guard let date = iso8601Formatter.date(from: try String(from: decoder)) else {
throw _dataCorrupted(at: decoder.codingPath, "Expected date string to be ISO8601-formatted.")
}
return date
}
/// Decode the `Date` as a string parsed by the given formatter.
public static func formatted(_ formatter: DateFormatter) -> ObjectDecoder.DateDecodingStrategy {
return .custom { decoder in
guard let date = formatter.date(from: try String(from: decoder)) else {
throw _dataCorrupted(at: decoder.codingPath, "Date string does not match format expected by formatter.")
}
return date
}
}
}
extension ObjectDecoder.DecodingStrategy where T == Decimal {
public static let compatibleWithJSONDecoder = ObjectDecoder.DecodingStrategy<Decimal>.custom { decoder in
if let decimal = decoder.object as? Decimal {
return decimal
} else {
return Decimal(try Double(from: decoder))
}
}
}
extension ObjectDecoder.DecodingStrategy where T == Double {
public static let deferredToDouble: ObjectDecoder.DoubleDecodingStrategy? = nil
public static func convertNonConformingFloatFromString(_ positiveInfinity: String,
_ negativeInfinity: String,
_ nan: String) -> ObjectDecoder.DoubleDecodingStrategy {
return .custom { decoder in
if let double = decoder.object as? Double {
return double
} else if let string = decoder.object as? String {
if string == positiveInfinity {
return .infinity
} else if string == negativeInfinity {
return -.infinity
} else if string == nan {
return .nan
}
}
throw _typeMismatch(at: decoder.codingPath, expectation: Double.self, reality: decoder.object)
}
}
}
extension ObjectDecoder.DecodingStrategy where T == Float {
public static let deferredToFloat: ObjectDecoder.FloatDecodingStrategy? = nil
public static func convertNonConformingFloatFromString(_ positiveInfinity: String,
_ negativeInfinity: String,
_ nan: String) -> ObjectDecoder.FloatDecodingStrategy {
return .custom { decoder in
if let float = decoder.object as? Float {
return float
} else if let string = decoder.object as? String {
if string == positiveInfinity {
return .infinity
} else if string == negativeInfinity {
return -.infinity
} else if string == nan {
return .nan
}
}
throw _typeMismatch(at: decoder.codingPath, expectation: Float.self, reality: decoder.object)
}
}
}
extension ObjectDecoder.DecodingStrategy where T == URL {
public static let compatibleWithJSONDecoder = ObjectDecoder.DecodingStrategy<URL>.custom { decoder in
guard let url = URL(string: try String(from: decoder)) else {
throw _dataCorrupted(at: decoder.codingPath, "Invalid URL string.")
}
return url
}
}
// swiftlint:disable:this file_length
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