Implementations of CommonDirs for Linux

Sources/Path+CommonDirectories.swift

@@ -1,24 +1,90 @@
 import Foundation
 
 extension Path {
-    // helper to allow search path and domain mask to be passed in
-    private static func pathFor(searchPathDirectory path: FileManager.SearchPathDirectory, domain: FileManager.SearchPathDomainMask = .userDomainMask) -> Path? {
-        guard let pathString = FileManager.default.urls(for: path, in: .userDomainMask).last?.relativeString else {
-            return nil
+    /// Returns a `Path` containing ``FileManager.default.currentDirectoryPath`.
+    public static var cwd: Path {
+        return Path(string: FileManager.default.currentDirectoryPath)
+    }
+
+    /// Returns a `Path` representing the root path.
+    public static var root: Path {
+        return Path(string: "/")
+    }
+
+    /// Returns a `Path` representing the user’s home directory
+    public static var home: Path {
+        let string: String
+      #if os(macOS)
+        if #available(OSX 10.12, *) {
+            string = FileManager.default.homeDirectoryForCurrentUser.path
+        } else {
+            string = NSHomeDirectory()
         }
+      #else
+        string = NSHomeDirectory()
+      #endif
+        return Path(string: string)
+    }
 
+    /// Helper to allow search path and domain mask to be passed in.
+    private static func path(for searchPath: FileManager.SearchPathDirectory) -> Path {
+    #if os(Linux)
+        // the urls(for:in:) function is not implemented on Linux
+        //TODO strictly we should first try to use the provided binary tool
+
+        let foo = { ProcessInfo.processInfo.environment[$0].flatMap(Path.init) ?? $1 }
+
+        switch searchPath {
+        case .documentDirectory:
+            return Path.home/"Documents"
+        case .applicationSupportDirectory:
+            return foo("XDG_DATA_HOME", Path.home/".local/share")
+        case .cachesDirectory:
+            return foo("XDG_CACHE_HOME", Path.home/".cache")
+        default:
+            fatalError()
+        }
+    #else    
+        guard let pathString = FileManager.default.urls(for: searchPath, in: .userDomainMask).first?.path else {
+            switch searchPath {
+            case .documentDirectory:
+                return Path.home/"Documents"
+            case .applicationSupportDirectory:
+                return Path.home/"Library/Application Support"
+            case .cachesDirectory:
+                return Path.home/"Library/Caches"
+            default:
+                fatalError()
+            }
+        }
         return Path(string: pathString)
+    #endif
     }
 
-    public static var documents: Path? {
-        return pathFor(searchPathDirectory: .documentDirectory)
+    /**
+     The root for user documents.
+     - Note: There is no standard location for documents on Linux, thus we return `~/Documents`.
+     - Note: You should create a subdirectory before creating any files.
+     */
+    public static var documents: Path {
+        return path(for: .documentDirectory)
     }
 
-    public static var caches: Path? {
-        return pathFor(searchPathDirectory: .cachesDirectory)
+    /**
+     The root for cache files.
+     - Note: On Linux this is 'XDG_CACHE_HOME'.
+     - Note: You should create a subdirectory before creating any files.
+     */
+    public static var caches: Path {
+        return path(for: .cachesDirectory)
     }
 
-    public static var applicationSupport: Path? {
-        return pathFor(searchPathDirectory: .applicationSupportDirectory)
+    /**
+     For data that supports your running application.
+     - Note: On Linux is `XDG_DATA_HOME`.
+     - Note: You should create a subdirectory before creating any files.
+     */
+    public static var applicationSupport: Path {
+        return path(for: .applicationSupportDirectory)
     }
 }

Sources/Path.swift

@@ -16,31 +16,6 @@ public struct Path: Equatable, Hashable, Comparable {
     /// The underlying filesystem path
     public let string: String
 
-    /// Returns a `Path` containing ``FileManager.default.currentDirectoryPath`.
-    public static var cwd: Path {
-        return Path(string: FileManager.default.currentDirectoryPath)
-    }
-
-    /// Returns a `Path` representing the root path.
-    public static var root: Path {
-        return Path(string: "/")
-    }
-
-    /// Returns a `Path` representing the user’s home directory
-    public static var home: Path {
-        let string: String
-      #if os(macOS)
-        if #available(OSX 10.12, *) {
-            string = FileManager.default.homeDirectoryForCurrentUser.path
-        } else {
-            string = NSHomeDirectory()
-        }
-      #else
-        string = NSHomeDirectory()
-      #endif
-        return Path(string: string)
-    }
-
     /**
      Returns the filename extension of this path.
      - Remark: Implemented via `NSString.pathExtension`.