symlink: don't coerce type

Author: scivision

+stdlib/filename.m

@@ -17,7 +17,7 @@
 if isunix()
   pat = '[^/]*$';
 else
-  pat = ['[^/\\]*$'];
+  pat = '[^/\\]*$';
 end
 
 m = regexp(p, pat, 'match', 'once');

+stdlib/is_symlink.m

@@ -11,7 +11,7 @@
   ok = isSymbolicLink(p);
 catch e
   switch e.identifier
-    case "MATLAB:UndefinedFunction", ok = java.nio.file.Files.isSymbolicLink(javaPathObject(stdlib.absolute(p, "", false)));
+    case "MATLAB:UndefinedFunction", ok = java.nio.file.Files.isSymbolicLink(javaPathObject(stdlib.absolute(p, '', false)));
     case "Octave:undefined-function", ok = S_ISLNK(stat(p).mode);
     otherwise, rethrow(e)
   end

+stdlib/read_symlink.m

@@ -10,25 +10,29 @@
 
 try
   [ok, r] = isSymbolicLink(p);
-  if ~ok, r = ""; end
+  if ~ok, r = ''; end
 catch e
   switch e.identifier
     case "Octave:undefined-function", r = readlink(p);
     case "MATLAB:UndefinedFunction"
       if stdlib.is_symlink(p)
         % must be absolute path
         % must not be .canonical or symlink is gobbled!
-        r = stdlib.absolute(p, "", false);
+        r = stdlib.absolute(p, '', false);
 
         % https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/nio/file/Files.html#readSymbolicLink(java.nio.file.Path)
         r = java.nio.file.Files.readSymbolicLink(javaPathObject(r)).string;
       else
-        r = "";
+        r = '';
       end
     otherwise, rethrow(e)
   end
 end
 
+if isstring(p)
+  r = string(r);
+end
+
 end
 
 %!test

test/TestSymlink.m

@@ -37,7 +37,8 @@ function test_is_symlink(tc, p)
 function test_read_symlink(tc)
 
 tc.verifyEqual(stdlib.read_symlink(""), "")
-tc.verifyEqual(stdlib.read_symlink("not-exist"), "")
+tc.verifyEqual(stdlib.read_symlink(''), '')
+tc.verifyEqual(stdlib.read_symlink(tempname), '')
 tc.verifyEqual(stdlib.read_symlink(tc.target), "")
 
 t = stdlib.read_symlink(tc.link);
@@ -51,7 +52,7 @@ function test_read_symlink(tc)
 function test_create_symlink(tc)
 tc.applyFixture(matlab.unittest.fixtures.SuppressedWarningsFixture(["MATLAB:io:filesystem:symlink:TargetNotFound","MATLAB:io:filesystem:symlink:FileExists"]))
 
-tc.verifyFalse(stdlib.create_symlink("", tempname()))
+tc.verifyFalse(stdlib.create_symlink('', tempname()))
 tc.verifyFalse(stdlib.create_symlink(tc.target, tc.link), "should fail for existing symlink")
 
 ano = tc.tempDir + "/another.lnk";