src/Pure/General/file.scala

   {
     if (Platform.is_windows && flag) Isabelle_System.chmod("a+x", path)
     else if (Platform.is_windows) Isabelle_System.chmod("a-x", path)
     else path.file.setExecutable(flag, false)
   }
+
+
+  /* content */
+
+  object Content
+  {
+    def apply(path: Path, content: Bytes): Content = new Content_Bytes(path, content)
+    def apply(path: Path, content: String): Content = new Content_String(path, content)
+    def apply(path: Path, content: XML.Body): Content_XML = new Content_XML(path, content)
+  }
+
+  trait Content
+  {
+    def path: Path
+    def write(dir: Path): Unit
+  }
+
+  final class Content_Bytes private[File](val path: Path, content: Bytes) extends Content
+  {
+    def write(dir: Path): Unit = Bytes.write(dir + path, content)
+  }
+
+  final class Content_String private[File](val path: Path, content: String) extends Content
+  {
+    def write(dir: Path): Unit = File.write(dir + path, content)
+  }
+
+  final class Content_XML private[File](val path: Path, content: XML.Body)
+  {
+    def output(out: XML.Body => String): Content_String =
+      new Content_String(path, out(content))
+  }
 }