master 22c1f00 1/2: Allow string-slice to take zero-length matches

[Lars Ingebrigtsen]

branch: master
commit 22c1f00d997d38ba0c453da5f5e9c526d0ac05b0
Author: Lars Ingebrigtsen <larsi@gnus.org>
Commit: Lars Ingebrigtsen <larsi@gnus.org>

    Allow string-slice to take zero-length matches
    
    * lisp/emacs-lisp/subr-x.el (string-slice): Allow zero-length
    matches.  Code adapted from s.el by Magnar Sveen.
---
 lisp/emacs-lisp/subr-x.el            | 23 ++++++++++-------------
 test/lisp/emacs-lisp/subr-x-tests.el |  4 +++-
 2 files changed, 13 insertions(+), 14 deletions(-)

diff --git a/lisp/emacs-lisp/subr-x.el b/lisp/emacs-lisp/subr-x.el
index 09c4649..8a9424c 100644
--- a/lisp/emacs-lisp/subr-x.el
+++ b/lisp/emacs-lisp/subr-x.el
@@ -308,19 +308,16 @@ If OMIT-NULLS, empty lines will be removed from the 
results."
 
 (defun string-slice (string regexp)
   "Split STRING at REGEXP boundaries and return a list of slices.
-The boundaries that match REGEXP are included in the result."
-  (let ((start-substring 0)
-        (start-search 0)
-        (result nil))
-    (save-match-data
-      (while (string-match regexp string start-search)
-        (if (zerop (match-beginning 0))
-            (setq start-search (match-end 0))
-          (push (substring string start-substring (match-beginning 0)) result)
-          (setq start-substring (match-beginning 0)
-                start-search (match-end 0))))
-      (push (substring string start-substring) result)
-      (nreverse result))))
+The boundaries that match REGEXP are included in the result.
+
+Also see `split-string'."
+  (if (zerop (length string))
+      (list "")
+    (let ((i (string-match-p regexp string 1)))
+      (if i
+          (cons (substring string 0 i)
+                (string-slice (substring string i) regexp))
+        (list string)))))
 
 (defun string-pad (string length &optional padding start)
   "Pad STRING to LENGTH using PADDING.
diff --git a/test/lisp/emacs-lisp/subr-x-tests.el 
b/test/lisp/emacs-lisp/subr-x-tests.el
index 854d61e..3fc5f1d 100644
--- a/test/lisp/emacs-lisp/subr-x-tests.el
+++ b/test/lisp/emacs-lisp/subr-x-tests.el
@@ -608,7 +608,9 @@
   (should (equal (string-slice "foo-bar" "-") '("foo" "-bar")))
   (should (equal (string-slice "foo-bar-" "-") '("foo" "-bar" "-")))
   (should (equal (string-slice "-foo-bar-" "-") '("-foo" "-bar" "-")))
-  (should (equal (string-slice "ooo" "lala") '("ooo"))))
+  (should (equal (string-slice "ooo" "lala") '("ooo")))
+  (should (equal (string-slice "foo bar" "\\b") '("foo" " " "bar" "")))
+  (should (equal (string-slice "foo bar" "\\b\\|a") '("foo" " " "b" "ar" ""))))
 
 (ert-deftest subr-string-pad ()
   (should (equal (string-pad "foo" 5) "foo  "))