Add Swift 4 support

Package@swift-4.swift

@@ -0,0 +1,47 @@
+// swift-tools-version:4.0
+// The swift-tools-version declares the minimum version of Swift required to build this package.
+
+/**
+ * Copyright IBM Corporation 2016, 2017
+ *
+ * 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 PackageDescription
+
+let package = Package(
+    name: "Kitura-WebSocket",
+    products: [
+        // Products define the executables and libraries produced by a package, and make them visible to other packages.
+        .library(
+            name: "Kitura-WebSocket",
+            targets: ["KituraWebSocket"]),
+        ],
+    dependencies: [
+        // Dependencies declare other packages that this package depends on.
+        // .package(url: /* package url */, from: "1.0.0"),
+        .package(url: "https://github.com/IBM-Swift/Kitura-net.git", .upToNextMinor(from: "1.7.0")),
+        .package(url: "https://github.com/IBM-Swift/BlueCryptor.git", .upToNextMinor(from: "0.8.0")),
+
+    ],
+    targets: [
+        // Targets are the basic building blocks of a package. A target defines a module or a test suite.
+        // Targets can depend on other targets in this package, and on products in packages which this package depends on.
+        .target(
+            name: "KituraWebSocket",
+            dependencies: ["Kitura-net", "Cryptor"]),
+        .testTarget(
+            name: "KituraWebSocketTests",
+            dependencies: ["KituraWebSocket"]),
+        ]
+)

Tests/KituraWebSocketTests/PrintLogger.swift

@@ -74,6 +74,10 @@ public class PrintLogger: Logger {
         guard let range = path.range(of: "/", options: .backwards) else {
             return path
         }
-        return path.substring(from: range.upperBound)
+        #if swift(>=3.2)
+            return String(path[range.upperBound...])
+        #else
+            return path.substring(from: range.upperBound)
+        #endif
     }
 }

Tests/KituraWebSocketTests/TestLinuxSafeguard.swift

@@ -14,7 +14,7 @@
  * limitations under the License.
  **/
 
-#if os(OSX)
+#if os(OSX) && !swift(>=3.2)
     import XCTest
 
     class TestLinuxSafeguard: XCTestCase {