join, is_absolute: correct/streamline

Author: scivision

+stdlib/is_absolute.m

@@ -3,7 +3,7 @@
 % on non-Windows, absolute paths must start with a slash
 
 
-function isabs = is_absolute(p, use_java)
+function y = is_absolute(p, use_java)
 arguments
   p (1,1) string
   use_java (1,1) logical = false
@@ -14,34 +14,39 @@
 if use_java
   % java is about 5x to 10x slower than intrinsic
   % https://docs.oracle.com/en/java/javase/22/docs/api/java.base/java/io/File.html#isAbsolute()
-  isabs = javaFileObject(p).toPath().isAbsolute();
+  y = javaFileObject(p).isAbsolute();
 
 else
+  y = false;
+  L = stdlib.len(p);
+  if ~L || (ispc && L < 3)
+    return
+  end
 
-  L = strlength(p);
   if ispc
-    s = "";
-    if L > 2
+    if ischar(p)
+      s = p(3); %#ok<UNRCH>
+    else
       s = extractBetween(p, 3, 3);
     end
-    isabs = L > 2 && strlength(stdlib.root_name(p)) && (strcmp(s, '/') || strcmp(s, '\'));
+    y = stdlib.len(stdlib.root_name(p)) && (strcmp(s, '/') || strcmp(s, '\'));
   else
-    isabs = L >= 1 && startsWith(p, "/");
+    y = strncmp(p, "/", 1);
   end
 
 end
 
 end
 
-%!assert(is_absolute(''), false)
+%!assert(is_absolute('',0), false)
 %!test
 %! if ispc
-%!   assert(is_absolute('C:\'))
-%!   assert(is_absolute('C:/'))
-%!   assert(!is_absolute('C:'))
-%!   assert(!is_absolute('C'))
+%!   assert(is_absolute('C:\', 0))
+%!   assert(is_absolute('C:/', 0))
+%!   assert(!is_absolute('C:', 0))
+%!   assert(!is_absolute('C', 0))
 %! else
-%!   assert(is_absolute('/'))
-%!   assert(is_absolute('/usr'))
-%!   assert(!is_absolute('usr'))
+%!   assert(is_absolute('/',0))
+%!   assert(is_absolute('/usr',0))
+%!   assert(!is_absolute('usr',0))
 %! endif

+stdlib/join.m

@@ -8,15 +8,15 @@
 end
 
 
-b = stdlib.drop_slash(base);
-o = stdlib.drop_slash(other);
-
 if use_java
-  r = javaFileObject(b).toPath().resolve(o);
+  r = javaFileObject(base).toPath().resolve(other);
   p = jPosix(r);
 else
 
-if startsWith(o, "/") || (ispc && stdlib.is_absolute(o))
+b = stdlib.drop_slash(base);
+o = stdlib.drop_slash(other);
+
+if startsWith(o, "/") || (ispc && stdlib.is_absolute(o, false))
   p = o;
   return
 end

example/bench_is_absolute.m

@@ -0,0 +1,12 @@
+a1 = "c:/a/";
+
+fno = @() stdlib.is_absolute(a1, false);
+fjava = @() stdlib.is_absolute(a1, 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")

example/bench_join.m

@@ -0,0 +1,13 @@
+a1 = "a/";
+b1 = "b/c";
+
+fno = @() stdlib.join(a1, b1, false);
+fjava = @() stdlib.join(a1, b1, 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")