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/*
This source file is part of the Swift.org open source project
Copyright (c) 2014 - 2017 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
*/
/// A type which can be mapped from JSON.
public protocol JSONMappable {
/// Create an object from given JSON.
init(json: JSON) throws
}
extension JSON {
/// Describes an error occurred during JSON mapping.
public enum MapError: Error {
/// The key is missing in JSON.
case missingKey(String)
/// Got a different type than expected.
case typeMismatch(key: String, expected: Any.Type, json: JSON)
/// A custom error. Clients can use this in their mapping method.
case custom(key: String?, message: String)
}
/// Returns a JSON mappable object from a given key.
public func get<T: JSONMappable>(_ key: String) throws -> T {
let object: JSON = try get(key)
return try T(json: object)
}
public func get<T: JSONMappable>(_ type: T.Type, forKey key: String) throws -> T {
let object: JSON = try get(key)
return try T(json: object)
}
/// Returns an optional JSON mappable object from a given key.
public func get<T: JSONMappable>(_ key: String) -> T? {
if let object: JSON = try? get(key) {
return try? T.init(json: object)
}
return nil
}
/// Returns a JSON mappable array from a given key.
public func get<T: JSONMappable>(_ key: String) throws -> [T] {
let array: [JSON] = try get(key)
return try array.map(T.init(json:))
}
public func get<T: JSONMappable>(_ type: [T].Type, forKey key: String) throws -> [T] {
let array: [JSON] = try get(key)
return try array.map(T.init(json:))
}
/// Returns a JSON mappable dictionary from a given key.
public func get<T: JSONMappable>(_ key: String) throws -> [String: T] {
let object: JSON = try get(key)
guard case .dictionary(let value) = object else {
throw MapError.typeMismatch(
key: key, expected: Dictionary<String, JSON>.self, json: object)
}
return try value.mapValues({ try T.init(json: $0) })
}
/// Returns a JSON mappable dictionary from a given key.
public func get(_ key: String) throws -> [String: JSON] {
let object: JSON = try get(key)
guard case .dictionary(let value) = object else {
throw MapError.typeMismatch(
key: key, expected: Dictionary<String, JSON>.self, json: object)
}
return value
}
/// Returns JSON entry in the dictionary from a given key.
public func get(_ key: String) throws -> JSON {
guard case .dictionary(let dict) = self else {
throw MapError.typeMismatch(
key: key, expected: Dictionary<String, JSON>.self, json: self)
}
guard let object = dict[key] else {
throw MapError.missingKey(key)
}
return object
}
public func getJSON(_ key: String) throws -> JSON {
return try get(key)
}
/// Returns JSON array entry in the dictionary from a given key.
public func get(_ key: String) throws -> [JSON] {
let object: JSON = try get(key)
guard case .array(let array) = object else {
throw MapError.typeMismatch(key: key, expected: Array<JSON>.self, json: object)
}
return array
}
public func getArray(_ key: String) throws -> [JSON] {
return try get(key)
}
public func getArray() throws -> [JSON] {
guard case .array(let array) = self else {
throw MapError.typeMismatch(key: "<self>", expected: Array<JSON>.self, json: self)
}
return array
}
}
// MARK: - Conformance for basic JSON types.
extension Int: JSONMappable {
public init(json: JSON) throws {
guard case .int(let int) = json else {
throw JSON.MapError.custom(key: nil, message: "expected int, got \(json)")
}
self = int
}
}
extension String: JSONMappable {
public init(json: JSON) throws {
guard case .string(let str) = json else {
throw JSON.MapError.custom(key: nil, message: "expected string, got \(json)")
}
self = str
}
}
extension Bool: JSONMappable {
public init(json: JSON) throws {
guard case .bool(let bool) = json else {
throw JSON.MapError.custom(key: nil, message: "expected bool, got \(json)")
}
self = bool
}
}
extension Double: JSONMappable {
public init(json: JSON) throws {
guard case .double(let double) = json else {
throw JSON.MapError.custom(key: nil, message: "expected double, got \(json)")
}
self = double
}
}
extension Array where Element: JSONMappable {
public init(json: JSON) throws {
guard case .array(let array) = json else {
throw JSON.MapError.custom(key: nil, message: "expected array, got \(json)")
}
self = try array.map({ try Element(json: $0) })
}
}
extension Dictionary where Key == String, Value: JSONMappable {
public init(json: JSON) throws {
guard case .dictionary(let dictionary) = json else {
throw JSON.MapError.custom(key: nil, message: "expected dictionary, got \(json)")
}
self = try dictionary.mapValues({ try Value(json: $0) })
}
}
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