1 files changed, 22 insertions, 0 deletions
diff --git a/lisp/subr.el b/lisp/subr.el
index ef0e5e6f780..1b93fcf4100 100644
--- a/lisp/subr.el
+++ b/lisp/subr.el
@@ -6200,6 +6200,28 @@ returned list are in the same order as in TREE.
 ;; for discoverability:
 (defalias 'flatten-list #'flatten-tree)
 
+(defun string-trim-left (string &optional regexp)
+  "Trim STRING of leading string matching REGEXP.
+
+REGEXP defaults to \"[ \\t\\n\\r]+\"."
+  (if (string-match (concat "\\`\\(?:" (or regexp "[ \t\n\r]+") "\\)") string)
+      (substring string (match-end 0))
+    string))
+
+(defun string-trim-right (string &optional regexp)
+  "Trim STRING of trailing string matching REGEXP.
+
+REGEXP defaults to  \"[ \\t\\n\\r]+\"."
+  (let ((i (string-match-p (concat "\\(?:" (or regexp "[ \t\n\r]+") "\\)\\'")
+                           string)))
+    (if i (substring string 0 i) string)))
+
+(defun string-trim (string &optional trim-left trim-right)
+  "Trim STRING of leading and trailing strings matching TRIM-LEFT and TRIM-RIGHT.
+
+TRIM-LEFT and TRIM-RIGHT default to \"[ \\t\\n\\r]+\"."
+  (string-trim-left (string-trim-right string trim-right) trim-left))
+
 ;; The initial anchoring is for better performance in searching matches.
 (defconst regexp-unmatchable "\\`a\\`"
   "Standard regexp guaranteed not to match any string at all.")