Add FileName for the name property of files

Resolves #2

Sources/FileBuilder/File/DataFile.swift

@@ -3,17 +3,17 @@ import Foundation
 
 public struct DataFile: File {
 
-    private let name: String
+    private let name: FileName
     private let data: Data
 
-    public init(_ name: String, data: Data) {
+    public init(_ name: FileName, data: Data) {
         self.name = name
         self.data = data
     }
 
     public var file: some File {
         BuiltinFile { directory, _ in
-            let url = directory.appendingPathComponent(name)
+            let url = directory.appending(name)
             try data.write(to: url)
         }
     }

Sources/FileBuilder/File/Directory.swift

@@ -3,11 +3,11 @@ import Foundation
 
 public struct Directory<Content: File>: File {
 
-    private let name: String
+    private let name: FileName
     private let content: Content
 
     public init(
-        _ name: String,
+        _ name: FileName,
         @FileBuilder content: () -> Content
     ) {
         self.name = name
@@ -16,7 +16,7 @@ public struct Directory<Content: File>: File {
 
     public var file: some File {
         BuiltinFile { directory, environment in
-            let url = directory.appendingPathComponent(name)
+            let url = directory.appending(name)
             try FileManager().createDirectory(at: url, withIntermediateDirectories: true)
             try content.write(in: url, environment: environment)
         }
@@ -25,7 +25,7 @@ public struct Directory<Content: File>: File {
 
 extension Directory<Empty> {
 
-    public init(_ name: String) {
+    public init(_ name: FileName) {
         self.init(name) {
             Empty()
         }

Sources/FileBuilder/File/FileName.swift

@@ -0,0 +1,30 @@
+import Foundation
+
+public struct FileName: Equatable, Hashable {
+    fileprivate let value: String
+    public init(_ value: String) {
+        self.value = value
+    }
+}
+
+extension FileName: ExpressibleByStringLiteral {
+    public init(stringLiteral value: String) {
+        self.init(value)
+    }
+}
+
+extension FileName: ExpressibleByStringInterpolation {}
+
+extension FileName: CustomStringConvertible {
+    public var description: String { value }
+}
+
+extension FileName: CustomDebugStringConvertible {
+    public var debugDescription: String { value }
+}
+
+extension URL {
+    func appending(_ name: FileName) -> URL {
+        appendingPathComponent(name.value)
+    }
+}

Sources/FileBuilder/File/TextFile.swift

@@ -4,11 +4,11 @@ import Foundation
 public struct TextFile<Content: Text>: File {
 
     @Environment(\.stringEncoding) private var encoding: String.Encoding
-    private let name: String
+    private let name: FileName
     private let text: Content
 
     public init(
-        _ name: String,
+        _ name: FileName,
         @TextBuilder text: () -> Content
     ) {
         self.name = name
@@ -21,12 +21,12 @@ public struct TextFile<Content: Text>: File {
             guard let data = string.data(using: encoding) else {
                 throw TextFileFailure(name: name)
             }
-            let url = directory.appendingPathComponent(name)
+            let url = directory.appending(name)
             try data.write(to: url)
         }
     }
 }
 
 struct TextFileFailure: Error {
-    let name: String
+    let name: FileName
 }