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Pods/Alamofire/Source/CachedResponseHandler.swift

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+//
+//  CachedResponseHandler.swift
+//
+//  Copyright (c) 2019 Alamofire Software Foundation (http://alamofire.org/)
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in
+//  all copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+//  THE SOFTWARE.
+//
+
+import Foundation
+
+/// A type that handles whether the data task should store the HTTP response in the cache.
+public protocol CachedResponseHandler {
+    /// Determines whether the HTTP response should be stored in the cache.
+    ///
+    /// The `completion` closure should be passed one of three possible options:
+    ///
+    ///   1. The cached response provided by the server (this is the most common use case).
+    ///   2. A modified version of the cached response (you may want to modify it in some way before caching).
+    ///   3. A `nil` value to prevent the cached response from being stored in the cache.
+    ///
+    /// - Parameters:
+    ///   - task:       The data task whose request resulted in the cached response.
+    ///   - response:   The cached response to potentially store in the cache.
+    ///   - completion: The closure to execute containing cached response, a modified response, or `nil`.
+    func dataTask(_ task: URLSessionDataTask,
+                  willCacheResponse response: CachedURLResponse,
+                  completion: @escaping (CachedURLResponse?) -> Void)
+}
+
+// MARK: -
+
+/// `ResponseCacher` is a convenience `CachedResponseHandler` making it easy to cache, not cache, or modify a cached
+/// response.
+public struct ResponseCacher {
+    /// Defines the behavior of the `ResponseCacher` type.
+    public enum Behavior {
+        /// Stores the cached response in the cache.
+        case cache
+        /// Prevents the cached response from being stored in the cache.
+        case doNotCache
+        /// Modifies the cached response before storing it in the cache.
+        case modify((URLSessionDataTask, CachedURLResponse) -> CachedURLResponse?)
+    }
+
+    /// Returns a `ResponseCacher` with a `.cache` `Behavior`.
+    public static let cache = ResponseCacher(behavior: .cache)
+    /// Returns a `ResponseCacher` with a `.doNotCache` `Behavior`.
+    public static let doNotCache = ResponseCacher(behavior: .doNotCache)
+
+    /// The `Behavior` of the `ResponseCacher`.
+    public let behavior: Behavior
+
+    /// Creates a `ResponseCacher` instance from the `Behavior`.
+    ///
+    /// - Parameter behavior: The `Behavior`.
+    public init(behavior: Behavior) {
+        self.behavior = behavior
+    }
+}
+
+extension ResponseCacher: CachedResponseHandler {
+    public func dataTask(_ task: URLSessionDataTask,
+                         willCacheResponse response: CachedURLResponse,
+                         completion: @escaping (CachedURLResponse?) -> Void) {
+        switch behavior {
+        case .cache:
+            completion(response)
+        case .doNotCache:
+            completion(nil)
+        case let .modify(closure):
+            let response = closure(task, response)
+            completion(response)
+        }
+    }
+}
+
+extension CachedResponseHandler where Self == ResponseCacher {
+    /// Provides a `ResponseCacher` which caches the response, if allowed. Equivalent to `ResponseCacher.cache`.
+    public static var cache: ResponseCacher { .cache }
+
+    /// Provides a `ResponseCacher` which does not cache the response. Equivalent to `ResponseCacher.doNotCache`.
+    public static var doNotCache: ResponseCacher { .doNotCache }
+
+    /// Creates a `ResponseCacher` which modifies the proposed `CachedURLResponse` using the provided closure.
+    ///
+    /// - Parameter closure: Closure used to modify the `CachedURLResponse`.
+    /// - Returns:           The `ResponseCacher`.
+    public static func modify(using closure: @escaping ((URLSessionDataTask, CachedURLResponse) -> CachedURLResponse?)) -> ResponseCacher {
+        ResponseCacher(behavior: .modify(closure))
+    }
+}