Re: Patch: Syntax and Hard Newlines

[Herbert Euler]

> I don't think that is a real test, because merely enabling Emacs Lisp
> mode does not parse anything.  You need to do some parsing
> across the buffer.

What about this?  The same file with 4185181 lines, totally 204MB.

(let (time-diff
     state)
 (save-window-excursion
   (let (old-time)
     (switch-to-buffer "large_file")
     (emacs-lisp-mode)
     (setq parse-sexp-lookup-properties nil
           old-time (current-time))
     (goto-char (point-max))
     (setq state (syntax-ppss (point))
           time-diff (time-subtract (current-time)
                                    old-time))))
 (pp state)
 time-diff)
    -| (0 nil 213444184 nil nil nil 0 nil nil nil)
    => (0 25 882543)

(let (time-diff
     state)
 (save-window-excursion
   (let (old-time)
     (switch-to-buffer "large_file")
     (emacs-lisp-mode)
     (setq parse-sexp-lookup-properties t
           old-time (current-time))
     (goto-char (point-max))
     (setq state (syntax-ppss (point))
           time-diff (time-subtract (current-time)
                                    old-time))))
 (pp state)
 time-diff)
    -| (0 nil nil nil t nil 0 nil 1 nil)
    => (0 20 81466)

(let (time-diff
     state)
 (save-window-excursion
   (let (old-time)
     (switch-to-buffer "large_file")
     (emacs-lisp-mode)
     (setq parse-sexp-lookup-properties nil
           old-time (current-time))
     (goto-char (point-max))
     (setq state (syntax-ppss (point))
           time-diff (time-subtract (current-time)
                                    old-time))))
 (pp state)
 time-diff)
    -| (0 nil 213444184 nil nil nil 0 nil nil nil)
    => (0 26 100278)

(let (time-diff
     state)
 (save-window-excursion
   (let (old-time)
     (switch-to-buffer "large_file")
     (emacs-lisp-mode)
     (setq parse-sexp-lookup-properties t
           old-time (current-time))
     (goto-char (point-max))
     (setq state (syntax-ppss (point))
           time-diff (time-subtract (current-time)
                                    old-time))))
 (pp state)
 time-diff)
    -| (0 nil nil nil t nil 0 nil 1 nil)
    => (0 20 88486)

(let (time-diff
     state)
 (save-window-excursion
   (let (old-time)
     (switch-to-buffer "large_file")
     (emacs-lisp-mode)
     (setq parse-sexp-lookup-properties nil
           old-time (current-time))
     (goto-char (point-max))
     (setq state (syntax-ppss (point))
           time-diff (time-subtract (current-time)
                                    old-time))))
 (pp state)
 time-diff)
    -| (0 nil 213444184 nil nil nil 0 nil nil nil)
    => (0 25 897448)

(let (time-diff
     state)
 (save-window-excursion
   (let (old-time)
     (switch-to-buffer "large_file")
     (emacs-lisp-mode)
     (setq parse-sexp-lookup-properties t
           old-time (current-time))
     (goto-char (point-max))
     (setq state (syntax-ppss (point))
           time-diff (time-subtract (current-time)
                                    old-time))))
 (pp state)
 time-diff)
    -| (0 nil nil nil t nil 0 nil 1 nil)
    => (0 20 48766)

I surprisedly found that it is faster of setting
`parse-sexp-lookup-properties' to t than setting it to nil.

Regards,
Guanpeng Xu

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