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- // Copyright 2024 Google LLC
- //
- // Licensed under the Apache License, Version 2.0 (the "License");
- // you may not use this file except in compliance with the License.
- // You may obtain a copy of the License at
- //
- // http://www.apache.org/licenses/LICENSE-2.0
- //
- // Unless required by applicable law or agreed to in writing, software
- // distributed under the License is distributed on an "AS IS" BASIS,
- // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- // See the License for the specific language governing permissions and
- // limitations under the License.
- import Foundation
- @available(macOS 10.15, iOS 13, tvOS 13, watchOS 6, *)
- @propertyWrapper
- public struct OptionalVariable<Value> where Value: Encodable {
- public private(set) var isSet: Bool = false
- public var wrappedValue: Value? {
- didSet {
- isSet = true
- }
- }
- // init called when var isn't initialized
- // it is important to define this otherwise the var gets initialized with nil value
- public init() {
- wrappedValue = nil
- isSet = false
- }
- // init called with explicit initialization either with nil or value
- public init(wrappedValue initialValue: Value?) {
- wrappedValue = initialValue
- isSet = true
- }
- public var projectedValue: Self {
- return self
- }
- }
- @available(macOS 10.15, iOS 13, tvOS 13, watchOS 6, *)
- extension OptionalVariable: Encodable {
- public func encode(to encoder: Encoder) throws {
- if isSet {
- var container = encoder.singleValueContainer()
- try container.encode(wrappedValue)
- }
- }
- }
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