Merge from trunk.

1 files changed, 32 insertions, 0 deletions

diff --git a/lisp/emacs-lisp/helpers.el b/lisp/emacs-lisp/helpers.el
index 73c2ff1c15c..8049f4e1d1d 100644
--- a/lisp/emacs-lisp/helpers.el
+++ b/lisp/emacs-lisp/helpers.el
@@ -37,6 +37,38 @@
     (maphash (lambda (_k v) (push v values)) hash-table)
     values))
 
+(defsubst string-empty-p (string)
+  "Check whether STRING is empty."
+  (string= string ""))
+
+(defsubst string-join (strings &optional separator)
+  "Join all STRINGS using SEPARATOR."
+  (mapconcat 'identity strings separator))
+
+(defsubst string-reverse (str)
+  "Reverse the string STR."
+  (apply 'string (nreverse (string-to-list str))))
+
+(defsubst string-trim-left (string)
+  "Remove leading whitespace from STRING."
+  (if (string-match "\\`[ \t\n\r]+" string)
+      (replace-match "" t t string)
+    string))
+
+(defsubst string-trim-right (string)
+  "Remove trailing whitespace from STRING."
+  (if (string-match "[ \t\n\r]+\\'" string)
+      (replace-match "" t t string)
+    string))
+
+(defsubst string-trim (string)
+  "Remove leading and trailing whitespace from STRING."
+  (string-trim-left (string-trim-right string)))
+
+(defsubst string-blank-p (string)
+  "Check whether STRING is either empty or only whitespace."
+  (string-empty-p (string-trim string)))
+
 (provide 'helpers)
 
 ;;; helpers.el ends here