(show-paren-mode): Support making show-paren-mode

a buffer-local variable.  Don't check for a window system.
(show-paren-function): Check whether show-paren-function is
enabled in current buffer; do the right thing if not.
Don't check for a window system.
(show-paren-mode): Make it a user variable.

1 files changed, 125 insertions, 107 deletions

diff --git a/lisp/paren.el b/lisp/paren.el
index b59b96e4f40..50af83bf3b2 100644
--- a/lisp/paren.el
+++ b/lisp/paren.el
@@ -41,7 +41,7 @@
 (defvar show-paren-overlay-1 nil)
 
 (defcustom show-paren-mode nil
-  "Toggle Show Paren mode.
+  "*Toggle Show Paren mode.
 When Show Paren mode is enabled, any matching parenthesis is highlighted
 after `show-paren-delay' seconds of Emacs idle time.
 Setting this variable directly does not take effect;
@@ -99,121 +99,139 @@ Returns the new status of Show Paren mode (non-nil means on).
 When Show Paren mode is enabled, any matching parenthesis is highlighted
 in `show-paren-style' after `show-paren-delay' seconds of Emacs idle time."
   (interactive "P")
-  (when window-system
-    (let ((on-p (if arg
-                    (> (prefix-numeric-value arg) 0)
-                  (not show-paren-mode))))
-      (setq blink-matching-paren-on-screen (not on-p))
-      (when show-paren-idle-timer
+  (let ((on-p (if arg
+                  (> (prefix-numeric-value arg) 0)
+                (not show-paren-mode))))
+    (setq show-paren-mode on-p)
+    ;; Turn off the usual paren-matching method
+    ;; when this one is turned on.
+    (if (local-variable-p 'show-paren-mode)
+        (make-local-variable 'blink-matching-paren-on-screen)
+      (kill-local-variable 'blink-matching-paren-on-screen))
+    (setq blink-matching-paren-on-screen (not on-p))
+
+    ;; Now enable or disable the mechanism.
+    ;; First get rid of the old idle timer.
+    (if show-paren-idle-timer
         (cancel-timer show-paren-idle-timer))
-      (if on-p
-          (setq show-paren-idle-timer (run-with-idle-timer
-                                       show-paren-delay t
-                                       'show-paren-function))
-        (and show-paren-overlay (overlay-buffer show-paren-overlay)
-             (delete-overlay show-paren-overlay))
-        (and show-paren-overlay-1 (overlay-buffer show-paren-overlay-1)
-             (delete-overlay show-paren-overlay-1)))
-      (setq show-paren-mode on-p))))
+    (setq show-paren-idle-timer nil)
+    ;; If show-paren-mode is enabled in some buffer now,
+    ;; set up a new timer.
+    (when (memq t (mapcar (lambda (buffer)
+                            (with-current-buffer buffer
+                              show-paren-mode))
+                          (buffer-list)))
+      (setq show-paren-idle-timer (run-with-idle-timer
+                                   show-paren-delay t
+                                   'show-paren-function)))
+    (unless on-p
+      (and show-paren-overlay
+           (eq (overlay-buffer show-paren-overlay) (current-buffer))
+           (delete-overlay show-paren-overlay))
+      (and show-paren-overlay-1
+           (eq (overlay-buffer show-paren-overlay-1) (current-buffer))
+           (delete-overlay show-paren-overlay-1)))))
 
 ;; Find the place to show, if there is one,
 ;; and show it until input arrives.
 (defun show-paren-function ()
-  ;; Do nothing if no window system to display results with.
-  ;; Do nothing if executing keyboard macro.
-  ;; Do nothing if input is pending.
-  (when window-system
-    (let (pos dir mismatch face (oldpos (point)))
-      (cond ((eq (char-syntax (preceding-char)) ?\))
-             (setq dir -1))
-            ((eq (char-syntax (following-char)) ?\()
-             (setq dir 1)))
-      ;;
-      ;; Find the other end of the sexp.
-      (when dir
-        (save-excursion
-          (save-restriction
-            ;; Determine the range within which to look for a match.
-            (when blink-matching-paren-distance
-              (narrow-to-region
-               (max (point-min) (- (point) blink-matching-paren-distance))
-               (min (point-max) (+ (point) blink-matching-paren-distance))))
-            ;; Scan across one sexp within that range.
-            ;; Errors or nil mean there is a mismatch.
-            (condition-case ()
-                (setq pos (scan-sexps (point) dir))
-              (error (setq pos t mismatch t)))
-            ;; If found a "matching" paren, see if it is the right
-            ;; kind of paren to match the one we started at.
-            (when (integerp pos)
-              (let ((beg (min pos oldpos)) (end (max pos oldpos)))
-                (when (/= (char-syntax (char-after beg)) ?\$)
-                  (setq mismatch
-                        (not (eq (char-before end)
-                                 ;; This can give nil.
-                                 (matching-paren (char-after beg)))))))))))
-      ;;
-      ;; Highlight the other end of the sexp, or unhighlight if none.
-      (if (not pos)
-          (progn
-            ;; If not at a paren that has a match,
-            ;; turn off any previous paren highlighting.
-            (and show-paren-overlay (overlay-buffer show-paren-overlay)
-                 (delete-overlay show-paren-overlay))
-            (and show-paren-overlay-1 (overlay-buffer show-paren-overlay-1)
-                 (delete-overlay show-paren-overlay-1)))
-        ;;
-        ;; Use the correct face.
-        (if mismatch
-            (progn
-              (if show-paren-ring-bell-on-mismatch
-                  (beep))
-              (setq face 'show-paren-mismatch-face))
-          (setq face 'show-paren-match-face))
+  (if show-paren-mode
+      (let (pos dir mismatch face (oldpos (point)))
+        (cond ((eq (char-syntax (preceding-char)) ?\))
+               (setq dir -1))
+              ((eq (char-syntax (following-char)) ?\()
+               (setq dir 1)))
         ;;
-        ;; If matching backwards, highlight the closeparen
-        ;; before point as well as its matching open.
-        ;; If matching forward, and the openparen is unbalanced,
-        ;; highlight the paren at point to indicate misbalance.
-        ;; Otherwise, turn off any such highlighting.
-        (if (and (= dir 1) (integerp pos))
-            (when (and show-paren-overlay-1
-                       (overlay-buffer show-paren-overlay-1))
-              (delete-overlay show-paren-overlay-1))
-          (let ((from (if (= dir 1)
-                          (point)
-                        (forward-point -1)))
-                (to (if (= dir 1)
-                        (forward-point 1)
-                      (point))))
-            (if show-paren-overlay-1
-                (move-overlay show-paren-overlay-1 from to (current-buffer))
-              (setq show-paren-overlay-1 (make-overlay from to)))
-            ;; Always set the overlay face, since it varies.
-            (overlay-put show-paren-overlay-1 'face face)))
+        ;; Find the other end of the sexp.
+        (when dir
+          (save-excursion
+            (save-restriction
+              ;; Determine the range within which to look for a match.
+              (when blink-matching-paren-distance
+                (narrow-to-region
+                 (max (point-min) (- (point) blink-matching-paren-distance))
+                 (min (point-max) (+ (point) blink-matching-paren-distance))))
+              ;; Scan across one sexp within that range.
+              ;; Errors or nil mean there is a mismatch.
+              (condition-case ()
+                  (setq pos (scan-sexps (point) dir))
+                (error (setq pos t mismatch t)))
+              ;; If found a "matching" paren, see if it is the right
+              ;; kind of paren to match the one we started at.
+              (when (integerp pos)
+                (let ((beg (min pos oldpos)) (end (max pos oldpos)))
+                  (when (/= (char-syntax (char-after beg)) ?\$)
+                    (setq mismatch
+                          (not (eq (char-before end)
+                                   ;; This can give nil.
+                                   (matching-paren (char-after beg)))))))))))
         ;;
-        ;; Turn on highlighting for the matching paren, if found.
-        ;; If it's an unmatched paren, turn off any such highlighting.
-        (unless (integerp pos)
-          (delete-overlay show-paren-overlay))
-        (let ((to (if (or (eq show-paren-style 'expression)
-                          (and (eq show-paren-style 'mixed)
-                               (not (pos-visible-in-window-p pos))))
-                      (point)
-                    pos))
-              (from (if (or (eq show-paren-style 'expression)
+        ;; Highlight the other end of the sexp, or unhighlight if none.
+        (if (not pos)
+            (progn
+              ;; If not at a paren that has a match,
+              ;; turn off any previous paren highlighting.
+              (and show-paren-overlay (overlay-buffer show-paren-overlay)
+                   (delete-overlay show-paren-overlay))
+              (and show-paren-overlay-1 (overlay-buffer show-paren-overlay-1)
+                   (delete-overlay show-paren-overlay-1)))
+          ;;
+          ;; Use the correct face.
+          (if mismatch
+              (progn
+                (if show-paren-ring-bell-on-mismatch
+                    (beep))
+                (setq face 'show-paren-mismatch-face))
+            (setq face 'show-paren-match-face))
+          ;;
+          ;; If matching backwards, highlight the closeparen
+          ;; before point as well as its matching open.
+          ;; If matching forward, and the openparen is unbalanced,
+          ;; highlight the paren at point to indicate misbalance.
+          ;; Otherwise, turn off any such highlighting.
+          (if (and (= dir 1) (integerp pos))
+              (when (and show-paren-overlay-1
+                         (overlay-buffer show-paren-overlay-1))
+                (delete-overlay show-paren-overlay-1))
+            (let ((from (if (= dir 1)
+                            (point)
+                          (forward-point -1)))
+                  (to (if (= dir 1)
+                          (forward-point 1)
+                        (point))))
+              (if show-paren-overlay-1
+                  (move-overlay show-paren-overlay-1 from to (current-buffer))
+                (setq show-paren-overlay-1 (make-overlay from to)))
+              ;; Always set the overlay face, since it varies.
+              (overlay-put show-paren-overlay-1 'face face)))
+          ;;
+          ;; Turn on highlighting for the matching paren, if found.
+          ;; If it's an unmatched paren, turn off any such highlighting.
+          (unless (integerp pos)
+            (delete-overlay show-paren-overlay))
+          (let ((to (if (or (eq show-paren-style 'expression)
                             (and (eq show-paren-style 'mixed)
                                  (not (pos-visible-in-window-p pos))))
-                        pos
-                      (save-excursion
-                        (goto-char pos)
-                        (forward-point (- dir))))))
-          (if show-paren-overlay
-              (move-overlay show-paren-overlay from to (current-buffer))
-            (setq show-paren-overlay (make-overlay from to))))
-        ;;
-        ;; Always set the overlay face, since it varies.
-        (overlay-put show-paren-overlay 'face face)))))
+                        (point)
+                      pos))
+                (from (if (or (eq show-paren-style 'expression)
+                              (and (eq show-paren-style 'mixed)
+                                   (not (pos-visible-in-window-p pos))))
+                          pos
+                        (save-excursion
+                          (goto-char pos)
+                          (forward-point (- dir))))))
+            (if show-paren-overlay
+                (move-overlay show-paren-overlay from to (current-buffer))
+              (setq show-paren-overlay (make-overlay from to))))
+          ;;
+          ;; Always set the overlay face, since it varies.
+          (overlay-put show-paren-overlay 'face face)))
+    ;; show-paren-mode is nil in this buffer.
+    (and show-paren-overlay
+         (delete-overlay show-paren-overlay))
+    (and show-paren-overlay-1
+         (delete-overlay show-paren-overlay-1))))
 
 (provide 'paren)