avy.el (avy-goto-whitespace-end): New command

* avy.el (avy--regex-candidates): Allow `group' to be a function.
(avy-jump): Pass `group' to `avy--regex-candidates'.

Fixes #278

avy.el

@@ -960,8 +960,11 @@ When GROUP is non-nil, (BEG . END) should delimit that regex group."
             (when (avy--visible-p (1- (point)))
               (when (or (null pred)
                         (funcall pred))
-                (push (cons (cons (match-beginning group)
+                (push (cons
+                       (if (numberp group)
+                           (cons (match-beginning group)
                                  (match-end group))
+                         (funcall group))
                        wnd) candidates)))))))
     (nreverse candidates)))
 
@@ -1233,20 +1236,22 @@ exist."
     (ignore #'ignore)
     (t (error "Unexpected style %S" style))))
 
-(cl-defun avy-jump (regex &key window-flip beg end action pred)
+(cl-defun avy-jump (regex &key window-flip beg end action pred group)
   "Jump to REGEX.
 The window scope is determined by `avy-all-windows'.
 When WINDOW-FLIP is non-nil, do the opposite of `avy-all-windows'.
 BEG and END narrow the scope where candidates are searched.
 ACTION is a function that takes point position as an argument.
-When PRED is non-nil, it's a filter for matching point positions."
+When PRED is non-nil, it's a filter for matching point positions.
+When GROUP is non-nil, it's either a match group in REGEX, or a function
+that returns a cons of match beginning and end."
   (setq avy-action (or action avy-action))
   (let ((avy-all-windows
          (if window-flip
              (not avy-all-windows)
            avy-all-windows)))
     (avy-process
-     (avy--regex-candidates regex beg end pred))))
+     (avy--regex-candidates regex beg end pred group))))
 
 (defun avy--generic-jump (regex window-flip &optional beg end)
   "Jump to REGEX.
@@ -1361,6 +1366,20 @@ BEG and END narrow the scope where candidates are searched."
               :beg beg
               :end end)))
 
+;;;###autoload
+(defun avy-goto-whitespace-end (arg &optional beg end)
+  "Jump to the end of a whitespace sequence.
+The window scope is determined by `avy-all-windows'.
+When ARG is non-nil, do the opposite of `avy-all-windows'.
+BEG and END narrow the scope where candidates are searched."
+  (interactive "P")
+  (avy-with avy-goto-whitespace-end
+    (avy-jump "[ \t]+\\|\n[ \t]*"
+              :window-flip arg
+              :beg beg
+              :end end
+              :group (lambda () (cons (point) (1+ (point)))))))
+
 (defun avy-goto-word-0-above (arg)
   "Jump to a word start between window start and point.
 The window scope is determined by `avy-all-windows'.