is_symlink: speedup

Author: scivision

+stdlib/+java/is_symlink.m

@@ -1,5 +1,9 @@
 function ok = is_symlink(file)
 
-ok = java.nio.file.Files.isSymbolicLink(javaAbsolutePath(file));
+try
+  ok = java.nio.file.Files.isSymbolicLink(javaAbsolutePath(file));
+catch e
+  javaException(e)
+end
 
 end

+stdlib/+legacy/canonical.m

@@ -6,7 +6,9 @@
 
 c = "";
 
-if stdlib.strempty(file), return, end
+if stdlib.strempty(file)
+  return
+end
 
 [s, r] = fileattrib(file);
 

+stdlib/+native/is_symlink.m

@@ -0,0 +1,12 @@
+function i = is_symlink(file)
+
+try
+  i = isSymbolicLink(file);
+catch e
+  if e.identifier ~= "MATLAB:UndefinedFunction"
+    rethrow(e)
+  end
+  i = logical.empty;
+end
+
+end

+stdlib/+sys/read_symlink.m

@@ -14,7 +14,7 @@
   % worried if searching for "Tag value: Symbolic Link" might be locale dependent
 end
 
-if stdlib.is_symlink(file)
+if stdlib.sys.is_symlink(file)
   [s, m] = system(cmd);
   if s == 0
     m = strip(string(m));

+stdlib/is_symlink.m

@@ -4,31 +4,36 @@
 % * file: path to check
 % * backend: backend to use
 %%% Outputs
-% * ok: true if path is a symbolic link
+% * i: true if path is a symbolic link
 % * b: backend used
 
-function [ok, b] = is_symlink(file, backend)
+function [i, b] = is_symlink(file, backend)
 arguments
-  file string
+  file (1,1) string
   backend (1,:) string = ["native", "java", "python", "dotnet", "sys"]
 end
 
-if ismember('native', backend) || stdlib.strempty(backend)
-  try
-    ok = isSymbolicLink(file);
-    b = "native";
-    return
-  catch e
-    if e.identifier ~= "MATLAB:UndefinedFunction"
-      rethrow(e)
-    end
+i = logical.empty;
+
+for b = backend
+  switch b
+    case "java"
+      i = stdlib.java.is_symlink(file);
+    case "native"
+      i = stdlib.native.is_symlink(file);
+    case "dotnet"
+      i = stdlib.dotnet.is_symlink(file);
+    case "python"
+      if stdlib.matlabOlderThan('R2022a'), continue, end
+      i = stdlib.python.is_symlink(file);
+    case "sys"
+      i = stdlib.sys.is_symlink(file);
+    otherwise
+      error("stdlib:hard_link_count:ValueError", "Unknown backend: %s", b)
   end
 
-  backend(ismember(backend, 'native')) = [];
+  if ~isempty(i)
+    return
+  end
 end
-
-o = stdlib.Backend(mfilename(), backend);
-b = o.backend;
-ok = o.func(file);
-
 end