Merge pull request #258 from Andrew-Lees11/Swift4.0

Feat: Add support for Swift 4.0

.travis.yml

@@ -1,11 +1,16 @@
 matrix:
   include:
+    - os: osx
+      osx_image: xcode9.2
+      env: SWIFT_VERSION=4.0.3
     - os: osx
       osx_image: xcode9.4
       env: SWIFT_VERSION=4.1
     - os: osx
       osx_image: xcode10
       env: SWIFT_VERSION=4.2
+    - os: linux
+      env: SWIFT_VERSION=4.0.3
     - os: linux
       env: SWIFT_VERSION=4.1
     - os: linux

Package.swift

@@ -1,4 +1,4 @@
-// swift-tools-version:4.1
+// swift-tools-version:4.0
 import PackageDescription
 
 let package = Package(

Sources/_SwiftSupport.swift

@@ -0,0 +1,38 @@
+import Foundation
+
+#if !swift(>=4.1)
+  public extension Sequence {
+    func compactMap<ElementOfResult>(_ transform: (Element) throws -> ElementOfResult?) rethrows -> [ElementOfResult] {
+      return try flatMap(transform)
+    }
+  }
+#endif
+
+#if !swift(>=4.1)
+  public extension Collection {
+    func index(_ i: Self.Index, offsetBy n: Int) -> Self.Index {
+        let indexDistance = Self.IndexDistance(n)
+        return index(i, offsetBy: indexDistance)
+    }
+  }
+#endif
+
+#if !swift(>=4.1)
+public extension TemplateSyntaxError {
+  public static func ==(lhs: TemplateSyntaxError, rhs: TemplateSyntaxError) -> Bool {
+    return lhs.reason == rhs.reason &&
+      lhs.description == rhs.description &&
+      lhs.token == rhs.token &&
+      lhs.stackTrace == rhs.stackTrace &&
+      lhs.templateName == rhs.templateName
+  }
+}
+#endif
+
+#if !swift(>=4.1)
+public extension Variable {
+  public static func ==(lhs: Variable, rhs: Variable) -> Bool {
+    return lhs.variable == rhs.variable
+  }
+}
+#endif