Combine examples

Other Projects/GitHub Search/GitHubSearchWithSwiftUI/Extension/Publisher.Extension.swift

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+//
+//  Publisher.Extension.swift
+//  GitHubSearchWithSwiftUI
+//
+//  Created by John Holdsworth on 09/07/2019.
+//  Copyright © 2019 jp.marty-suzuki. All rights reserved.
+//
+
+import Combine
+
+extension Publisher {
+
+    /// - seealso: https://twitter.com/peres/status/1136132104020881408
+    func flatMapLatest<T: Publisher>(_ transform: @escaping (Self.Output) -> T) -> Publishers.SwitchToLatest<T, Publishers.Map<Self, T>> where T.Failure == Self.Failure {
+        map(transform).switchToLatest()
+    }
+}
+
+extension Publisher {
+
+    static func empty() -> AnyPublisher<Output, Failure> {
+        return Publishers.Empty()
+            .eraseToAnyPublisher()
+    }
+
+    static func just(_ output: Output) -> AnyPublisher<Output, Failure> {
+        return Just(output)
+            .catch { _ in AnyPublisher<Output, Failure>.empty() }
+            .eraseToAnyPublisher()
+    }
+
+    static func fail(_ error: Failure) -> AnyPublisher<Output, Failure> {
+        return Publishers.Fail(error: error)
+            .eraseToAnyPublisher()
+    }
+}