* lisp/delsel.el (delete-selection-helper): New function, extracted from

delete-selection-pre-hook.
(delete-selection-pre-hook): Use it.
(delete-selection-self-insert-function): New function.
(delete-selection-self-insert-hooks): New hook.
(self-insert-command, self-insert-iso): Use it.
* lisp/electric.el (electric-pair-syntax): New function, extracted from
electric-pair-post-self-insert-function.
(electric-pair-post-self-insert-function): Use it.
(electric-pair-delete-selection-self-insert-function): New function.
(electric-pair-mode): Require delsel and setup
delete-selection-self-insert-hooks.

Fixes: debbugs:11520

3 files changed, 134 insertions, 61 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 7d532ba899f..6edf13719ce 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,18 @@
+2012-10-22  Simon Law  <sfllaw@sfllaw.ca>  (tiny change)
+
+        * delsel.el (delete-selection-helper): New function, extracted from
+        delete-selection-pre-hook.
+        (delete-selection-pre-hook): Use it.
+        (delete-selection-self-insert-function): New function.
+        (delete-selection-self-insert-hooks): New hook.
+        (self-insert-command, self-insert-iso): Use it.
+        * electric.el (electric-pair-syntax): New function, extracted from
+        electric-pair-post-self-insert-function.
+        (electric-pair-post-self-insert-function): Use it.
+        (electric-pair-delete-selection-self-insert-function): New function.
+        (electric-pair-mode): Require delsel and setup
+        delete-selection-self-insert-hooks (bug#11520).
+
 2012-10-20  Chong Yidong  <cyd@gnu.org>
 
         * vc/vc.el (vc-diff-internal): Set up Diff mode even if there are
@@ -8,8 +23,8 @@
 
 2012-10-20  Arne Jørgensen  <arne@arnested.dk>
 
-        * progmodes/flymake.el (flymake-create-temp-inplace): Use
-        file-truename.
+        * progmodes/flymake.el (flymake-create-temp-inplace):
+        Use file-truename.
 
 2012-10-20  Eli Zaretskii  <eliz@gnu.org>
 
diff --git a/lisp/delsel.el b/lisp/delsel.el
index a6435672201..09f58e086a2 100644
--- a/lisp/delsel.el
+++ b/lisp/delsel.el
@@ -47,6 +47,9 @@
 ;;  non-nil
 ;;      The normal case: delete the active region prior to executing
 ;;      the command which will insert replacement text.
+;;  hooks
+;;      For commands which need to dynamically determine this behaviour.
+;;      Each hook should return one of the above values or nil.
 
 ;;; Code:
 
@@ -71,66 +74,106 @@ any selection."
     (transient-mark-mode t)))
 
 (defun delete-active-region (&optional killp)
+  "Delete the active region.
+If KILLP in not-nil, the active region is killed instead of deleted."
   (if killp
       (kill-region (point) (mark))
     (delete-region (point) (mark)))
   t)
 
+(defun delete-selection-helper (type)
+  "Deletes selection according to TYPE:
+ 'yank
+     For commands which do a yank; ensures the region about to be
+     deleted isn't yanked.
+ 'supersede
+     Delete the active region and ignore the current command,
+     i.e. the command will just delete the region.
+ 'kill
+     `kill-region' is used on the selection, rather than
+     `delete-region'.  (Text selected with the mouse will typically
+     be yankable anyhow.)
+ non-nil
+     The normal case: delete the active region prior to executing
+     the command which will insert replacement text.
+ hooks
+     For commands which need to dynamically determine this behaviour.
+     Each hook should return one of the above values or nil."
+  (condition-case data
+      (cond ((eq type 'kill)
+             (delete-active-region t))
+            ((eq type 'yank)
+             ;; Before a yank command, make sure we don't yank the
+             ;; head of the kill-ring that really comes from the
+             ;; currently active region we are going to delete.
+             ;; That would make yank a no-op.
+             (when (and (string= (buffer-substring-no-properties
+                                  (point) (mark))
+                                 (car kill-ring))
+                        (fboundp 'mouse-region-match)
+                        (mouse-region-match))
+               (current-kill 1))
+             (delete-active-region))
+            ((eq type 'supersede)
+             (let ((empty-region (= (point) (mark))))
+               (delete-active-region)
+               (unless empty-region
+                 (setq this-command 'ignore))))
+            ((and (symbolp type) (not (booleanp type)))
+             (delete-selection-helper
+              (run-hook-with-args-until-success type)))
+            (type
+             (delete-active-region)
+             (if (and overwrite-mode
+                      (eq this-command 'self-insert-command))
+                 (let ((overwrite-mode nil))
+                   (self-insert-command
+                    (prefix-numeric-value current-prefix-arg))
+                   (setq this-command 'ignore)))))
+    ;; If ask-user-about-supersession-threat signals an error,
+    ;; stop safe_run_hooks from clearing out pre-command-hook.
+    (file-supersession (message "%s" (cadr data)) (ding))
+    (text-read-only
+     ;; This signal may come either from `delete-active-region' or
+     ;; `self-insert-command' (when `overwrite-mode' is non-nil).
+     ;; To avoid clearing out `pre-command-hook' we handle this case
+     ;; by issuing a simple message.  Note, however, that we do not
+     ;; handle all related problems: When read-only text ends before
+     ;; the end of the region, the latter is not deleted but any
+     ;; subsequent insertion will succeed.  We could avoid this case
+     ;; by doing a (setq this-command 'ignore) here.  This would,
+     ;; however, still not handle the case where read-only text ends
+     ;; precisely where the region starts: In that case the deletion
+     ;; would succeed but the subsequent insertion would fail with a
+     ;; text-read-only error.  To handle that case we would have to
+     ;; investigate text properties at both ends of the region and
+     ;; skip the deletion when inserting text is forbidden there.
+     (message "Text is read-only") (ding))))
+
 (defun delete-selection-pre-hook ()
+  "Normal hook run before commands that delete selections are executed.
+Commands which will delete the selection need a 'delete-selection
+property on their symbols; commands which insert text but don't
+have this property won't delete the selection.
+
+See `delete-selection-helper'.
+"
   (when (and delete-selection-mode transient-mark-mode mark-active
              (not buffer-read-only))
     (let ((type (and (symbolp this-command)
                      (get this-command 'delete-selection))))
-      (condition-case data
-          (cond ((eq type 'kill)
-                 (delete-active-region t))
-                ((eq type 'yank)
-                 ;; Before a yank command, make sure we don't yank the
-                 ;; head of the kill-ring that really comes from the
-                 ;; currently active region we are going to delete.
-                 ;; That would make yank a no-op.
-                 (when (and (string= (buffer-substring-no-properties
-                                      (point) (mark))
-                                     (car kill-ring))
-                            (fboundp 'mouse-region-match)
-                            (mouse-region-match))
-                   (current-kill 1))
-                 (delete-active-region))
-                ((eq type 'supersede)
-                 (let ((empty-region (= (point) (mark))))
-                   (delete-active-region)
-                   (unless empty-region
-                     (setq this-command 'ignore))))
-                (type
-                 (delete-active-region)
-                 (if (and overwrite-mode
-                          (eq this-command 'self-insert-command))
-                   (let ((overwrite-mode nil))
-                     (self-insert-command
-                      (prefix-numeric-value current-prefix-arg))
-                     (setq this-command 'ignore)))))
-         ;; If ask-user-about-supersession-threat signals an error,
-         ;; stop safe_run_hooks from clearing out pre-command-hook.
-        (file-supersession (message "%s" (cadr data)) (ding))
-        (text-read-only
-         ;; This signal may come either from `delete-active-region' or
-         ;; `self-insert-command' (when `overwrite-mode' is non-nil).
-         ;; To avoid clearing out `pre-command-hook' we handle this case
-         ;; by issuing a simple message.  Note, however, that we do not
-         ;; handle all related problems: When read-only text ends before
-         ;; the end of the region, the latter is not deleted but any
-         ;; subsequent insertion will succeed.  We could avoid this case
-         ;; by doing a (setq this-command 'ignore) here.  This would,
-         ;; however, still not handle the case where read-only text ends
-         ;; precisely where the region starts: In that case the deletion
-         ;; would succeed but the subsequent insertion would fail with a
-         ;; text-read-only error.  To handle that case we would have to
-         ;; investigate text properties at both ends of the region and
-         ;; skip the deletion when inserting text is forbidden there.
-         (message "Text is read-only") (ding))))))
-
-(put 'self-insert-command 'delete-selection t)
-(put 'self-insert-iso 'delete-selection t)
+      (delete-selection-helper type))))
+
+(defun delete-selection-self-insert-function ()
+  t)
+
+(defvar delete-selection-self-insert-hooks
+  '(delete-selection-self-insert-function)
+  "Abnormal hook run before commands that insert characters.
+This hook should return a TYPE that `delete-selection-helper' understands.")
+
+(put 'self-insert-command 'delete-selection 'delete-selection-self-insert-hooks)
+(put 'self-insert-iso 'delete-selection 'delete-selection-self-insert-hooks)
 
 (put 'yank 'delete-selection 'yank)
 (put 'clipboard-yank 'delete-selection 'yank)
diff --git a/lisp/electric.el b/lisp/electric.el
index 3108a0ed4c0..e6fa1df914f 100644
--- a/lisp/electric.el
+++ b/lisp/electric.el
@@ -301,14 +301,17 @@ This can be convenient for people who find it easier to hit ) than C-f."
   :version "24.1"
   :type 'boolean)
 
+(defun electric-pair-syntax (command-event)
+  (and electric-pair-mode
+       (let ((x (assq command-event electric-pair-pairs)))
+         (cond
+          (x (if (eq (car x) (cdr x)) ?\" ?\())
+          ((rassq command-event electric-pair-pairs) ?\))
+          (t (char-syntax command-event))))))
+
 (defun electric-pair-post-self-insert-function ()
   (let* ((syntax (and (eq (char-before) last-command-event) ; Sanity check.
-                      electric-pair-mode
-                      (let ((x (assq last-command-event electric-pair-pairs)))
-                        (cond
-                         (x (if (eq (car x) (cdr x)) ?\" ?\())
-                         ((rassq last-command-event electric-pair-pairs) ?\))
-                         (t (char-syntax last-command-event))))))
+                      (electric-pair-syntax last-command-event)))
          ;; FIXME: when inserting the closer, we should maybe use
          ;; self-insert-command, although it may prove tricky running
          ;; post-self-insert-hook recursively, and we wouldn't want to trigger
@@ -355,6 +358,12 @@ This can be convenient for people who find it easier to hit ) than C-f."
                (eq (char-syntax (following-char)) ?w)))
       (save-excursion (insert closer))))))
 
+(defun electric-pair-delete-selection-self-insert-function ()
+  (let ((syntax (electric-pair-syntax last-command-event)))
+    (if (and (memq syntax '(?\( ?\" ?\$)) (use-region-p))
+        'keep
+      t)))
+
 ;;;###autoload
 (define-minor-mode electric-pair-mode
   "Toggle automatic parens pairing (Electric Pair mode).
@@ -370,10 +379,16 @@ See options `electric-pair-pairs' and `electric-pair-skip-self'."
   :global t
   :group 'electricity
   (if electric-pair-mode
-      (add-hook 'post-self-insert-hook
-                #'electric-pair-post-self-insert-function)
+      (progn
+        (require 'delsel)
+        (add-hook 'post-self-insert-hook
+                  #'electric-pair-post-self-insert-function)
+        (add-hook 'delete-selection-self-insert-hooks
+                  #'electric-pair-delete-selection-self-insert-function))
     (remove-hook 'post-self-insert-hook
-                 #'electric-pair-post-self-insert-function)))
+                 #'electric-pair-post-self-insert-function)
+    (remove-hook 'delete-selection-self-insert-hooks
+                  #'electric-pair-delete-selection-self-insert-function)))
 
 ;; Automatically add newlines after/before/around some chars.