Add `byte-optimizer' to `buffer-string', `backward-char' and `char-before'.

;; Thanks for Shuhei KOBAYASHI's suggestion.

diff --git a/lisp/dgnushack.el b/lisp/dgnushack.el
index 051c2f5..1715518 100644 (file)
--- a/lisp/dgnushack.el
+++ b/lisp/dgnushack.el
@@ -49,6 +49,29 @@
     (fset 'x-defined-colors 'ignore)
     (fset 'read-color 'ignore)))
 
+(eval-and-compile
+  (put 'buffer-string 'byte-optimizer 'byte-optimize-buffer-string)
+  (defun byte-optimize-buffer-string (form)
+    (if (null (cdr form))
+       (list 'buffer-substring (list 'point-min)(list 'point-max))
+      form))
+
+  (put 'backward-char 'byte-optimizer 'byte-optimize-backward-char)
+  (defun byte-optimize-backward-char (form)
+    (if (null (cdr form))
+       (list 'forward-char -1)
+      (list 'forward-char (list '- (nth 1 form)))))
+
+  (when (or (featurep 'xemacs)
+           (and (= emacs-major-version 20)
+                (> emacs-minor-version 2)))
+    ;; this optimization is not safe under Emacs 20.2 and before.
+    (put 'char-before 'byte-optimizer 'byte-optimize-char-before)
+    (defun byte-optimize-char-before (form)
+      (if (null (cdr form))
+         (list 'char-after (list '1- (list 'point)))
+       (list 'char-after (list '1- (nth 1 form)))))))
+
 (defun dgnushack-compile (&optional warn)
   ;;(setq byte-compile-dynamic t)
   (unless warn