(split-string): Handle empty matches reasonably.

diff --git a/lisp/subr.el b/lisp/subr.el
index cadb2fd313f689553510bc5f85725caa5a20b03f..5afb4215940196a5e555a54f54297f2129cdd121 100644 (file)
--- a/lisp/subr.el
+++ b/lisp/subr.el
@@ -983,12 +983,25 @@ STRING should be given if the last search was by `string-match' on STRING."
 Each match for SEPARATORS is a splitting point.
 The substrings between the splitting points are made into a list
 which is returned.
-If SEPARATORS is absent, it defaults to \"[ \\f\\t\\n\\r\\v]+\"."
+If SEPARATORS is absent, it defaults to \"[ \\f\\t\\n\\r\\v]+\".
+
+If there is match for SEPARATORS at the beginning of STRING, we do not
+include a null substring for that.  Likewise, if there is a match
+at the end of STRING, we don't include a null substring for that."
   (let ((rexp (or separators "[ \f\t\n\r\v]+"))
        (start 0)
+       notfirst
        (list nil))
-    (while (string-match rexp string start)
+    (while (and (string-match rexp string
+                             (if (and notfirst
+                                      (= start (match-beginning 0))
+                                      (< start (length string)))
+                                 (1+ start) start))
+               (< (match-beginning 0) (length string)))
+      (setq notfirst t)
       (or (eq (match-beginning 0) 0)
+         (and (eq (match-beginning 0) (match-end 0))
+              (eq (match-beginning 0) start))
          (setq list
                (cons (substring string start (match-beginning 0))
                      list)))