exists,is{read,writ}able: use intrinsic vs. Java for 10x speedup

Author: scivision

+stdlib/exists.m

@@ -1,11 +1,20 @@
-function ok = exists(p)
+function ok = exists(p, use_java)
 %% exists does path exist
 % https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/io/File.html#exists()
 
 arguments
   p (1,1) string
+  use_java (1,1) logical = false
+end
+
+if use_java
+% Java takes 2x to 10x as long as intrinsic way worst case
+% the intrinsic way above is at least not slower
+
+  ok = java.io.File(p).exists();
+else
+  ok = isfile(p) || isfolder(p);
 end
 
-ok = java.io.File(p).exists();
 
 end

+stdlib/is_readable.m

@@ -1,14 +1,22 @@
-function ok = is_readable(file)
+function ok = is_readable(file, use_jvm)
 %% is_readable is file readable
 % https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/nio/file/Files.html#isReadable(java.nio.file.Path)
 
 arguments
   file (1,1) string
+  use_jvm (1,1) logical = false
 end
 
-% needs absolute()
-file = stdlib.absolute(file);
+if use_jvm
+  % java is about 10x slower than fileattrib
+  % needs absolute()
+  file = stdlib.absolute(file);
 
-ok = java.nio.file.Files.isReadable(java.io.File(file).toPath());
+  ok = java.nio.file.Files.isReadable(java.io.File(file).toPath());
+else
+  [status, v] = fileattrib(file);
+
+  ok = status ~= 0 && (v.UserRead || (~isnan(v.GroupRead) && v.GroupRead) || (~isnan(v.OtherRead) && v.OtherRead));
+end
 
 end

+stdlib/is_writable.m

@@ -1,15 +1,23 @@
-function ok = is_writable(file)
+function ok = is_writable(file, use_jvm)
 %% is_writable
 % is path writable
 % https://docs.oracle.com/en/java/javase/22/docs/api/java.base/java/nio/file/Files.html#isWritable(java.nio.file.Path)
 
 arguments
   file (1,1) string
+  use_jvm (1,1) logical = false
 end
 
-% needs absolute()
-file = stdlib.absolute(file);
+if use_jvm
+  % java is about 10x slower than fileattrib
+  % needs absolute()
+  file = stdlib.absolute(file);
 
-ok = java.nio.file.Files.isWritable(java.io.File(file).toPath());
+  ok = java.nio.file.Files.isWritable(java.io.File(file).toPath());
+else
+  [status, v] = fileattrib(file);
+
+  ok = status ~= 0 && (v.UserWrite || (~isnan(v.GroupWrite) && v.GroupWrite) || (~isnan(v.OtherWrite) && v.OtherWrite));
+end
 
 end