root: enhance/correct Java

Author: scivision

+stdlib/parent.m

@@ -7,7 +7,7 @@
 end
 
 % https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/io/File.html#getParent()
-% java was 10x slower and not correct for input like C:
+% java was 10x slower and not correct for input like C:/
 
 p = stdlib.drop_slash(pth);
 

+stdlib/private/jPosix.m

@@ -0,0 +1,17 @@
+function s = jPosix(o)
+
+  d = "";
+
+  if isempty(o)
+    s = "";
+  else
+    s = o.toString();
+  end
+
+  if isa(d, "string")
+    s = string(s);
+  end
+
+  s = stdlib.posix(s);
+
+end

+stdlib/root.m

@@ -10,19 +10,12 @@
 end
 
 
-r = "";
-if stdlib.len(p) == 0
-  return
-end
-
-
 if stdlib.isoctave()
   o = javaObject("java.io.File", p).toPath().getRoot();
-  if ~isempty(o)
-    r = stdlib.posix(o.toString());
-  end
+  r = jPosix(o);
 elseif use_java
-  r = stdlib.posix(java.io.File(p).toPath().getRoot().toString());
+  o = java.io.File(p).toPath().getRoot();
+  r = jPosix(o);
 else
 
   r = stdlib.root_name(p);