Shift platform detection to utility

Author: aciidgh

Sources/Build/misc.swift

@@ -185,29 +185,23 @@ extension SystemPackageProvider {
         }
     }
 
-    static func providerForCurrentPlatform(providers: [SystemPackageProvider]) -> SystemPackageProvider? {
-        guard let uname = try? popen(["uname"]).chomp().lowercased() else { return nil }
-        switch uname {
-        case "darwin":
-            for provider in providers {
-                if case .Brew = provider {
-                    return provider
-                }
+    var isAvailable: Bool {
+        guard let platform = Platform.currentPlatform() else { return false }
+        switch self {
+        case .Brew(_):
+            if case .Darwin = platform  {
+                return true
             }
-        case "linux":
-            if "/etc/debian_version".isFile {
-                for provider in providers {
-                    if case .Apt = provider {
-                        return provider
-                    }
-                }
+        case .Apt(_):
+            if case .Linux(.Debian) = platform  {
+                return true
             }
-            break
-            
-        default:
-            return nil
         }
-        return nil
+        return false
+    }
+    
+    static func providerForCurrentPlatform(providers: [SystemPackageProvider]) -> SystemPackageProvider? {
+        return providers.filter{ $0.isAvailable }.first
     }
 }
 

Sources/Utility/Platform.swift

@@ -0,0 +1,35 @@
+/*
+ This source file is part of the Swift.org open source project
+ 
+ Copyright 2015 - 2016 Apple Inc. and the Swift project authors
+ Licensed under Apache License v2.0 with Runtime Library Exception
+ 
+ See http://swift.org/LICENSE.txt for license information
+ See http://swift.org/CONTRIBUTORS.txt for Swift project authors
+*/
+
+import func POSIX.popen
+
+public enum Platform {
+    case Darwin
+    case Linux(LinuxFlavor)
+    
+    public enum LinuxFlavor {
+        case Debian
+    }
+    
+    public static func currentPlatform() -> Platform? {
+        guard let uname = try? popen(["uname"]).chomp().lowercased() else { return nil }
+        switch uname {
+        case "darwin":
+            return .Darwin
+        case "linux":
+            if "/etc/debian_version".isFile {
+                return .Linux(.Debian)
+            }
+        default:
+            return nil
+        }
+        return nil
+    }
+}