Re: display-completion-list should not strip text properties

[Markus Triska]

Chong Yidong <address@hidden> writes:

> 1997-11-02 emacs-lisp/byte-opt.el (byte-optimize-concat): New function.
> Revertable.  (It's an optional optimization.)

This had evolved into a more general and worthwhile optimisation for
several pure functions. Here's an independent implementation:

2007-04-11  Markus Triska  <address@hidden>

        * emacs-lisp/byte-opt.el (byte-optimize-form-code-walker):
        evaluate pure function calls if possible
        (byte-optimize-all-constp): new function

Index: byte-opt.el
===================================================================
RCS file: /sources/emacs/emacs/lisp/emacs-lisp/byte-opt.el,v
retrieving revision 1.93
diff -c -r1.93 byte-opt.el
*** byte-opt.el 11 Apr 2007 03:57:11 -0000      1.93
--- byte-opt.el 11 Apr 2007 15:43:41 -0000
***************
*** 557,564 ****
           ;; Otherwise, no args can be considered to be for-effect,
           ;; even if the called function is for-effect, because we
           ;; don't know anything about that function.
!          (cons fn (mapcar 'byte-optimize-form (cdr form)))))))
! 
  
  (defun byte-optimize-form (form &optional for-effect)
    "The source-level pass of the optimizer."
--- 557,576 ----
           ;; Otherwise, no args can be considered to be for-effect,
           ;; even if the called function is for-effect, because we
           ;; don't know anything about that function.
!          (let ((args (mapcar #'byte-optimize-form (cdr form))))
!            (if (and (get fn 'pure)
!                     (byte-optimize-all-constp args))
!                  (list 'quote (apply fn (mapcar #'eval args)))
!              (cons fn args)))))))
! 
! (defun byte-optimize-all-constp (list)
!   "Non-nil iff all elements of LIST satisfy `byte-compile-constp'."
!   (let ((constant t))
!     (while (and list constant)
!       (unless (byte-compile-constp (car list))
!       (setq constant nil))
!       (setq list (cdr list)))
!     constant))
  
  (defun byte-optimize-form (form &optional for-effect)
    "The source-level pass of the optimizer."
***************
*** 1241,1246 ****
--- 1253,1270 ----
      (setq side-effect-and-error-free-fns (cdr 
side-effect-and-error-free-fns)))
    nil)
  
+ 
+ ;; pure functions are side-effect free functions whose values depend
+ ;; only on their arguments. For these functions, calls with constant
+ ;; arguments can be evaluated at compile time. This may shift run time
+ ;; errors to compile time.
+ 
+ (let ((pure-fns
+        '(concat symbol-name regexp-opt regexp-quote string-to-syntax)))
+   (while pure-fns
+     (put (car pure-fns) 'pure t)
+     (setq pure-fns (cdr pure-fns)))
+   nil)
  
  (defun byte-compile-splice-in-already-compiled-code (form)
    ;; form is (byte-code "..." [...] n)