JSON Codable

JSON.swift

import Foundation

enum JSON {
    case null
    case bool(Bool)
    case int64(Int64)
    case double(Double)
    case string(String)
    indirect case array([JSON])
    indirect case dictionary([String: JSON])
}

extension JSON {
    struct CodingKeys: CodingKey {
        var stringValue: String

        init(stringValue: String) {
            self.stringValue = stringValue
        }

        var intValue: Int?

        init?(intValue: Int) {
            self.init(stringValue: "\(intValue)")
            self.intValue = intValue
        }
    }
}

extension JSON: Decodable {
    init(from decoder: Decoder) throws {
        if let container = try? decoder.container(keyedBy: CodingKeys.self) {
            self = JSON(from: container)
        } else if let container = try? decoder.unkeyedContainer() {
            self = JSON(from: container)
        } else if let container = try? decoder.singleValueContainer() {
            self = try JSON(from: container)
        } else {
            throw DecodingError.dataCorrupted(DecodingError.Context(codingPath: [], debugDescription: ""))
        }
    }

    private init(from container: SingleValueDecodingContainer) throws {
        if container.decodeNil() {
            self = .null
        } else if let value = try? container.decode(Bool.self) {
            self = .bool(value)
        } else if let value = try? container.decode(Int64.self) {
            self = .int64(value)
        } else if let value = try? container.decode(Double.self) {
            self = .double(value)
        } else if let value = try? container.decode(String.self) {
            self = .string(value)
        } else {
            throw DecodingError.dataCorrupted(DecodingError.Context(codingPath: [], debugDescription: ""))
        }
    }

    private init(from container: UnkeyedDecodingContainer) {
        var container = container
        var array: [JSON] = []
        while !container.isAtEnd {
            if let isNil = try? container.decodeNil(), isNil {
                array.append(.null)
            } else if let value = try? container.decode(Bool.self) {
                array.append(.bool(value))
            } else if let value = try? container.decode(Int64.self) {
                array.append(.int64(value))
            } else if let value = try? container.decode(Double.self) {
                array.append(.double(value))
            } else if let value = try? container.decode(String.self) {
                array.append(.string(value))
            } else if let value = try? container.nestedContainer(keyedBy: CodingKeys.self) {
                array.append(JSON(from: value))
            } else if let value = try? container.nestedUnkeyedContainer() {
                array.append(JSON(from: value))
            }
        }
        self = .array(array)
    }

    private init(from container: KeyedDecodingContainer<CodingKeys>) {
        var dict: [String: JSON] = [:]
        for key in container.allKeys {
            if let isNil = try? container.decodeNil(forKey: key), isNil {
                dict[key.stringValue] = .null
            } else if let value = try? container.decode(Bool.self, forKey: key) {
                dict[key.stringValue] = .bool(value)
            } else if let value = try? container.decode(Int64.self, forKey: key) {
                dict[key.stringValue] = .int64(value)
            } else if let value = try? container.decode(Double.self, forKey: key) {
                dict[key.stringValue] = .double(value)
            } else if let value = try? container.decode(String.self, forKey: key) {
                dict[key.stringValue] = .string(value)
            } else if let value = try? container.nestedContainer(keyedBy: CodingKeys.self, forKey: key) {
                dict[key.stringValue] = JSON(from: value)
            } else if let value = try? container.nestedUnkeyedContainer(forKey: key) {
                dict[key.stringValue] = JSON(from: value)
            }
        }
        self = .dictionary(dict)
    }
}

extension JSON: Encodable {
    func encode(to encoder: Encoder) throws {
        switch self {
        case .null:
            var container = encoder.singleValueContainer()
            try container.encodeNil()
        case .bool(let value):
            var container = encoder.singleValueContainer()
            try container.encode(value)
        case .int64(let value):
            var container = encoder.singleValueContainer()
            try container.encode(value)
        case .double(let value):
            var container = encoder.singleValueContainer()
            try container.encode(value)
        case .string(let value):
            var container = encoder.singleValueContainer()
            try container.encode(value)
        case .array(let array):
            var container = encoder.unkeyedContainer()
            for value in array {
                try container.encode(value)
            }
        case .dictionary(let dict):
            var container = encoder.container(keyedBy: CodingKeys.self)
            for (key, value) in dict {
                try container.encode(value, forKey: CodingKeys(stringValue: key))
            }
        }
    }
}

extension JSON: CustomDebugStringConvertible {
    var debugDescription: String {
        switch self {
        case .null:
            return "null"
        case .bool(let value):
            return String(value)
        case .int64(let value):
            return String(value)
        case .double(let value):
            return String(value)
        case .string(let value):
            return String(value)
        case .array(let array):
            let value = array.map { $0.debugDescription }.joined(separator: ", ")
            return "[\(value)]"
        case .dictionary(let dict):
            let value = dict.keys.map { key in "\(key): \(dict[key]!.debugDescription)" }.joined(separator: ", ")
            return "{\(value)}"
        }
    }
}