Nix some useless uses of looking-at, looking-back

* lisp/allout.el (allout-kill-topic):
(allout-next-topic-pending-encryption):
* lisp/bookmark.el (bookmark-kill-line):
* lisp/cus-edit.el (custom-save-variables, custom-save-faces):
* lisp/cus-theme.el (custom-theme-write-variables):
(custom-theme-write-faces):
* lisp/emacs-lisp/autoload.el (autoload-generate-file-autoloads):
* lisp/emacs-lisp/bytecomp.el (byte-compile-from-buffer):
* lisp/emacs-lisp/checkdoc.el (checkdoc-interactive-loop):
(checkdoc-interactive-ispell-loop):
(checkdoc-message-interactive-ispell-loop, checkdoc-this-string-valid):
(checkdoc-this-string-valid-engine):
* lisp/emacs-lisp/elint.el (elint-get-top-forms):
* lisp/emulation/viper-cmd.el (viper-backward-indent):
* lisp/image-dired.el (image-dired-delete-char):
* lisp/simple.el (kill-visual-line): Replace instances of looking-at,
looking-back with char comparisons using following-char, preceding-char.

lisp/allout.el

@@ -4462,7 +4462,7 @@ Topic exposure is marked with text-properties, to be used by
     (if (and (/= (current-column) 0) (not (eobp)))
         (forward-char 1))
     (if (not (eobp))
-	(if (and (save-match-data (looking-at "\n"))
+	(if (and (= (following-char) ?\n)
                  (or (save-excursion
                        (or (not (allout-next-heading))
                            (= depth allout-recent-depth)))
@@ -6278,8 +6278,7 @@ It must also have content."
             (setq got nil
                   done t)
           (goto-char (setq got (match-beginning 0)))
-          (if (save-match-data (looking-at "\n"))
+          (when (= (following-char) ?\n) (forward-char 1))
-              (forward-char 1))
           (setq got (point)))
 
         (cond ((not got)

lisp/bookmark.el

@@ -896,8 +896,8 @@ If optional arg NEWLINE-TOO is non-nil, delete the newline too.
 Does not affect the kill ring."
   (let ((eol (line-end-position)))
     (delete-region (point) eol)
-    (if (and newline-too (looking-at "\n"))
+    (when (and newline-too (= (following-char) ?\n))
-        (delete-char 1))))
+      (delete-char 1))))
 
 
 ;; Defvars to avoid compilation warnings:

lisp/cus-edit.el

@@ -4581,7 +4581,7 @@ This function does not save the buffer."
       (if (bolp)
 	  (princ " "))
       (princ ")")
-      (unless (looking-at-p "\n")
+      (when (/= (following-char) ?\n)
 	(princ "\n")))))
 
 (defun custom-save-faces ()
@@ -4636,7 +4636,7 @@ This function does not save the buffer."
       (if (bolp)
 	  (princ " "))
       (princ ")")
-      (unless (looking-at-p "\n")
+      (when (/= (following-char) ?\n)
 	(princ "\n")))))
 
 ;;; The Customize Menu.

lisp/cus-theme.el

@@ -431,7 +431,7 @@ It includes all variables in list VARS."
       (if (bolp)
 	  (princ " "))
       (princ ")")
-      (unless (looking-at "\n")
+      (when (/= (following-char) ?\n)
 	(princ "\n")))))
 
 (defun custom-theme-write-faces (theme faces)
@@ -463,7 +463,7 @@ It includes all faces in list FACES."
 	      (princ ")")))))
       (if (bolp) (princ " "))
       (princ ")")
-      (unless (looking-at "\n")
+      (when (/= (following-char) ?\n)
 	(princ "\n")))))
 
 

lisp/emacs-lisp/autoload.el

@@ -748,7 +748,7 @@ FILE's modification time."
                               (setq output-start (autoload--setup-output
                                                   otherbuf outbuf absfile load-name)))
                             (autoload--print-cookie-text output-start load-name file))
-                           ((looking-at ";")
+                           ((= (following-char) ?\;)
                             ;; Don't read the comment.
                             (forward-line 1))
                            (t

lisp/emacs-lisp/bytecomp.el

@@ -1995,7 +1995,7 @@ With argument ARG, insert value in current buffer after the form."
 	;; Compile the forms from the input buffer.
 	(while (progn
 		 (while (progn (skip-chars-forward " \t\n\^l")
-			       (looking-at ";"))
+			       (= (following-char) ?\;))
 		   (forward-line 1))
 		 (not (eobp)))
 	  (setq byte-compile-read-position (point)

lisp/emacs-lisp/checkdoc.el

@@ -603,7 +603,7 @@ style."
 	      (checkdoc-overlay-put cdo 'face 'highlight)
 	      ;; Make sure the whole doc string is visible if possible.
 	      (sit-for 0)
-	      (if (and (looking-at "\"")
+	      (if (and (= (following-char) ?\")
 		       (not (pos-visible-in-window-p
 			     (save-excursion (forward-sexp 1) (point))
 			     (selected-window))))
@@ -743,9 +743,9 @@ buffer, otherwise searching starts at START-HERE."
       (while (checkdoc-next-docstring)
         (message "Searching for doc string spell error...%d%%"
                  (floor (* 100.0 (point)) (point-max)))
-        (if (looking-at "\"")
+        (when (= (following-char) ?\")
-            (checkdoc-ispell-docstring-engine
+          (checkdoc-ispell-docstring-engine
-             (save-excursion (forward-sexp 1) (point-marker)))))
+           (save-excursion (forward-sexp 1) (point-marker)))))
       (message "Checkdoc: Done."))))
 
 (defun checkdoc-message-interactive-ispell-loop (start-here)
@@ -763,7 +763,7 @@ buffer, otherwise searching starts at START-HERE."
       (while (checkdoc-message-text-next-string (point-max))
         (message "Searching for message string spell error...%d%%"
                  (floor (* 100.0 (point)) (point-max)))
-        (if (looking-at "\"")
+        (if (= (following-char) ?\")
             (checkdoc-ispell-docstring-engine
              (save-excursion (forward-sexp 1) (point-marker)))))
       (message "Checkdoc: Done."))))
@@ -1381,7 +1381,7 @@ See the style guide in the Emacs Lisp manual for more details."
 		"All variables and subroutines might as well have a \
 documentation string")
 	      (point) (+ (point) 1) t)))))
-    (if (and (not err) (looking-at "\""))
+    (if (and (not err) (= (following-char) ?\"))
         (with-syntax-table checkdoc-syntax-table
           (checkdoc-this-string-valid-engine fp))
       err)))
@@ -1395,7 +1395,7 @@ regexp short cuts work.  FP is the function defun information."
 	;; we won't accidentally lose our place.  This could cause
 	;; end-of doc string whitespace to also delete the " char.
 	(s (point))
-	(e (if (looking-at "\"")
+	(e (if (= (following-char) ?\")
 	       (save-excursion (forward-sexp 1) (point-marker))
 	     (point))))
     (or
@@ -1475,7 +1475,7 @@ regexp short cuts work.  FP is the function defun information."
 	((looking-at "[\\!?;:.)]")
 	 ;; These are ok
 	 nil)
-        ((and checkdoc-permit-comma-termination-flag (looking-at ","))
+        ((and checkdoc-permit-comma-termination-flag (= (following-char) ?,))
 	 nil)
 	(t
 	 ;; If it is not a complete sentence, let's see if we can

lisp/emacs-lisp/elint.el

@@ -372,7 +372,7 @@ Returns the forms."
 	(let ((elint-current-pos (point)))
 	  ;; non-list check could be here too. errors may be out of seq.
 	  ;; quoted check cannot be elsewhere, since quotes skipped.
-	  (if (looking-back "'" (1- (point)))
+	  (if (= (preceding-char) ?\')
 	      ;; Eg cust-print.el uses ' as a comment syntax.
 	      (elint-warning "Skipping quoted form `%c%.20s...'" ?\'
 			   (read (current-buffer)))

lisp/emulation/viper-cmd.el

@@ -4520,7 +4520,7 @@ One can use \\=`\\=` and \\='\\=' to temporarily jump 1 step back."
   (interactive)
   (if viper-cted
       (let ((p (point)) (c (current-column)) bol (indent t))
-	(if (looking-back "[0^]" (1- (point)))
+	(if (memq (preceding-char) '(?0 ?^))
 	    (progn
 	      (if (eq ?^ (preceding-char))
 		  (setq viper-preserve-indent t))

lisp/image-dired.el

@@ -1751,8 +1751,8 @@ Ask user for number of images to show and the delay in between."
   (interactive)
   (let ((inhibit-read-only t))
     (delete-char 1)
-    (if (looking-at " ")
+    (when (= (following-char) ?\s)
-        (delete-char 1))))
+      (delete-char 1))))
 
 ;;;###autoload
 (defun image-dired-display-thumbs-append ()

lisp/simple.el

@@ -6665,7 +6665,7 @@ even beep.)"
 	;; whether the trailing whitespace is highlighted.  But, it's
 	;; OK to just do this unconditionally.
 	(skip-chars-forward " \t")))
-    (kill-region opoint (if (and kill-whole-line (looking-at "\n"))
+    (kill-region opoint (if (and kill-whole-line (= (following-char) ?\n))
 			    (1+ (point))
 			  (point)))))