root_*: patttern, simplify

Author: scivision

+stdlib/root.m

@@ -2,9 +2,6 @@
 % ROOT(P) returns the root path of P.
 
 function r = root(p)
-arguments
-  p {mustBeTextScalar}
-end
 
 r = strcat(stdlib.root_name(p), stdlib.root_dir(p));
 

+stdlib/root_dir.m

@@ -1,6 +1,6 @@
 %% ROOT_DIR get root directory
 % Examples:
-
+%
 %% Windows
 % * root_dir('C:\path\to\file') returns '\'
 % * root_dir('C:path\to\file') returns ''
@@ -13,22 +13,19 @@
   p {mustBeTextScalar}
 end
 
-matches = regexp(p, '^([/\\])|^[A-Za-z]:([/\\])', 'tokens');
+sep = characterListPattern("/" + filesep());
 
-if isempty(matches)
+pat = (textBoundary + sep) | ...
+      (lookBehindBoundary(lettersPattern(1) + ":") + sep);
 
+r = extract(p, pat);
+if isempty(r)
   r = '';
   if isstring(p)
     r = "";
   end
-
-else
-
-  r = matches{1};
-  if iscell(r)
-    r = r{1};
-  end
-
+elseif iscell(r)
+  r = r{1};
 end
 
 end

+stdlib/root_name.m

@@ -10,21 +10,22 @@
   p {mustBeTextScalar}
 end
 
-r = '';
-
-if ~ispc() || strlength(p) < 2
-  % noop
+if ispc()
+  r = extract(p, textBoundary + lettersPattern(1) + ":");
+  if ~isempty(r) && iscell(r)
+    r = r{1};
+  end
 else
-  c = char(p);
+  r = '';
+end
 
-  if c(2) == ':' && isletter(c(1))
-    r = c(1:2);
+if isempty(r)
+  r = '';
+  if isstring(p)
+    r = "";
   end
 end
 
-if isstring(p)
-  r = string(r);
-end
 
 end
 

test/TestRoot.m

@@ -13,7 +13,7 @@ function test_root(tc, p)
 end
 
 function test_root_dir(tc, rd)
-tc.verifyEqual(stdlib.root_dir(rd{1}), rd{2})
+tc.verifyEqual(stdlib.root_dir(rd{1}), rd{2}, "root_dir(" + rd{1} + ")")
 end
 
 function test_root_name(tc, rn)