parent: show java way

Author: scivision

+stdlib/parent.m

@@ -1,24 +1,35 @@
 %% PARENT parent directory of path
 %
 
-function p = parent(pth)
+function p = parent(pth, use_java)
 arguments
   pth (1,1) string
+  use_java (1,1) logical = false
 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:/
-
 p = stdlib.drop_slash(pth);
 
-if is_root_stub(p)
+if ~stdlib.len(p)
+  p = ".";
+  return
+elseif is_root_stub(p)
   % 2 or 3 char drive letter
   if stdlib.len(p) == 2
     p = strcat(p, "/");
   end
   return
+elseif strcmp(p, stdlib.root(p, use_java))
+  return
 end
 
+
+if use_java
+% https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/io/File.html#getParent()
+% Java is about 20x slower than pure Matlab
+p = jPosix(javaFileObject(p).getParent());
+
+else
+
 j = strfind(p, '/');
 if isempty(j)
   p = "";
@@ -33,13 +44,14 @@
   return
 end
 
+p = stdlib.posix(p);
+
+end
 
 if ~stdlib.len(p)
   p = ".";
 end
 
-p = stdlib.posix(p);
-
 end
 
 

example/bench_exists.m

@@ -1,5 +1,3 @@
-%% benchmark for exists()
-
 f = mfilename("fullpath") + ".m";
 %f = tempname;
 

example/bench_parent.m

@@ -0,0 +1,13 @@
+f = mfilename("fullpath") + ".m";
+%f = tempname;
+
+fno = @() stdlib.parent(f, false);
+fjava = @() stdlib.parent(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/TestParent.m

@@ -1,14 +1,15 @@
 classdef TestParent < matlab.unittest.TestCase
 
 properties (TestParameter)
-p_parent
+use_java = num2cell(unique([stdlib.has_java(), false]))
+p
 end
 
 methods(TestParameterDefinition, Static)
 
-function p_parent = init_parent()
+function p = init_parent()
 
-p_parent = {
+p = {
 {"", "."}, ...
 {".", "."}, ...
 {"..", "."}, ...
@@ -27,12 +28,12 @@
 };
 
 if ispc
-p_parent{12}{2} = "c:/";
-p_parent{13}{2} = "c:/";
-p_parent{14}{2} = "c:/a";
-p_parent{15}{2} = "c:/a";
-p_parent{end+1} =  {"c:/a", "c:/"};
-p_parent{end+1} = {"c:", "c:/"};
+p{12}{2} = "c:/";
+p{13}{2} = "c:/";
+p{14}{2} = "c:/a";
+p{15}{2} = "c:/a";
+p{end+1} =  {"c:/a", "c:/"};
+p{end+1} = {"c:", "c:/"};
 
 end
 
@@ -41,8 +42,8 @@
 
 
 methods (Test)
-function test_parent(tc, p_parent)
-tc.verifyEqual(stdlib.parent(p_parent{1}), p_parent{2}, p_parent{1})
+function test_parent(tc, p, use_java)
+tc.verifyEqual(stdlib.parent(p{1}, use_java), p{2}, p{1})
 end
 end