add file_size()

Author: scivision

+stdlib/file_size.m

@@ -0,0 +1,20 @@
+function s = file_size(p, use_java)
+arguments
+  p (1,1) string {mustBeFile}
+  use_java (1,1) logical = false
+end
+
+if use_java
+% several percent slower than native Matlab
+  s = java.io.File(p).length;
+else
+  s = dir(p);
+  if isempty(s)
+    s = [];
+  else
+    s = s.bytes;
+  end
+end
+
+
+end

example/bench_file_size.m

@@ -0,0 +1,14 @@
+%% benchmark for file_size()
+
+f = mfilename("fullpath") + ".m";
+
+fno = @() stdlib.file_size(f, false);
+fjava = @() stdlib.file_size(f, true);
+
+t_no = timeit(fno);
+t_java = timeit(fjava);
+
+disp("No Java: " + t_no + " s")
+disp("Java: " + t_java + " s")
+
+disp("Java is " + t_no/t_java + " times faster")

test/TestFileImpure.m

@@ -55,6 +55,10 @@ function test_exists(tc, p_exists)
 tc.verifyEqual(stdlib.exists(p_exists{1}), p_exists{2})
 end
 
+function test_file_size(tc)
+tc.verifyGreaterThan(stdlib.file_size(mfilename("fullpath") + ".m"), 0)
+end
+
 
 function test_is_readable(tc, p_exists)
 tc.verifyEqual(stdlib.is_readable(p_exists{1}), p_exists{2})