lib: fix uc_split() quirks

 - Ensure that split by string produces an initial empty string in the
   result array when the string to split starts with the split substring

 - Ensure that split by string produces a trailing empty string in the
   result array when the string to split ends with the split substring

Signed-off-by: Jo-Philipp Wich <jo@mein.io>

2 files changed, 13 insertions, 3 deletions

diff --git a/lib.c b/lib.c
index 5d6235d..20a1b81 100644
--- a/lib.c
+++ b/lib.c
@@ -967,7 +967,7 @@ uc_split(uc_vm *vm, size_t nargs)
 	else if (ucv_type(sep) == UC_STRING) {
 		sepstr = ucv_string_get(sep);
 
-		for (p = splitstr + (*sepstr ? 1 : 0), seplen = strlen(sepstr); *p; p++) {
+		for (p = splitstr, seplen = strlen(sepstr); *p; p++) {
 			if (!strncmp(p, sepstr, seplen)) {
 				if (*sepstr || p > splitstr)
 					ucv_array_push(arr, ucv_string_new_length(splitstr, p - splitstr));
@@ -977,8 +977,7 @@ uc_split(uc_vm *vm, size_t nargs)
 			}
 		}
 
-		if (*splitstr)
-			ucv_array_push(arr, ucv_string_new_length(splitstr, p - splitstr));
+		ucv_array_push(arr, ucv_string_new_length(splitstr, p - splitstr));
 	}
 	else {
 		ucv_put(arr);
diff --git a/tests/custom/03_bugs/13_split_by_string_leading_trailing b/tests/custom/03_bugs/13_split_by_string_leading_trailing
new file mode 100644
index 0000000..10a6062
--- /dev/null
+++ b/tests/custom/03_bugs/13_split_by_string_leading_trailing
@@ -0,0 +1,11 @@
+When splitting a string, the existing uc_split() implementation failed
+to produce an empty leading and trailing result array element when the
+subject string started or ended with a delimitter.
+
+-- Expect stdout --
+[ "", "foo", "" ]
+-- End --
+
+-- Testcase --
+{{ split("/foo/", "/") }}
+-- End --