add is_prefix()

Author: scivision

+stdlib/is_prefix.m

@@ -0,0 +1,30 @@
+%% IS_PREFIX is prefix a prefix of path?
+% canonicalization and normalization are NOT performed
+% duplicated slashes are dropped
+
+function s = is_prefix(prefix, pth)
+% arguments
+%   prefix (1,1) string
+%   pth (1,1) string
+% end
+
+pr = stdlib.drop_slash(prefix);
+p = stdlib.drop_slash(pth);
+
+if ischar(pr)
+  w = ~isempty(strfind(p, "..")) || ~isempty(strfind(pr, "..")); %#ok<STREMP>
+  s = strfind(p, pr) == 1 && (length(p) >= length(pr));
+else
+  w = contains(p, "..") || contains(pr, "..");
+  s = startsWith(p, pr) && (strlength(p) >= strlength(pr));
+end
+
+if ~strcmp(pr, p) && w
+  warning("is_prefix: %s and/or %s is ambiguous input with '..'  consider using stdlib.canonical() first", pr, p)
+end
+
+end
+
+%!assert(is_prefix("a", "a"))
+%!assert(is_prefix("a", "a/"))
+%!assert(is_prefix("a", "a/b"))

test/TestRelative.m

@@ -4,6 +4,7 @@
 p_relative_to
 p_proximate_to
 p_is_subdir
+p_is_prefix
 end
 
 
@@ -59,7 +60,7 @@
 end
 
 
-function [p_is_subdir] = init_is_subdir()
+function [p_is_subdir, p_is_prefix] = init_is_subdir()
 
 p_is_subdir = {
     {"a/b", "a/b", false}, ...
@@ -79,6 +80,15 @@
   p_is_subdir{end+1} = {"/", "/", false};
 end
 
+p_is_prefix = p_is_subdir;
+p_is_prefix{1}{3} = true;
+p_is_prefix{2}{3} = false;
+p_is_prefix{3}{3} = true;
+p_is_prefix{6}{3} = true;
+p_is_prefix{7}{3} = false;
+p_is_prefix{8}{3} = false;
+p_is_prefix{9}{3} = true;
+
 end
 
 end
@@ -110,10 +120,13 @@ function test_proximate_to(tc, p_proximate_to)
 
 
 function test_is_subdir(tc, p_is_subdir)
-tc.assumeTrue(stdlib.has_java)
 tc.verifyEqual(stdlib.is_subdir(p_is_subdir{1}, p_is_subdir{2}), p_is_subdir{3}, "subdir(" + p_is_subdir{1} + "," + p_is_subdir{2} + ")")
 end
 
+function test_is_prefix(tc, p_is_prefix)
+tc.verifyEqual(stdlib.is_prefix(p_is_prefix{1}, p_is_prefix{2}), p_is_prefix{3}, "prefix(" + p_is_prefix{1} + "," + p_is_prefix{2} + ")")
+end
+
 end
 
 end