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* lisp/emacs-lisp/pcase.el: Undo last change's spurious changes

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This commit is contained in:
Stefan Monnier 2016-05-30 16:35:00 -04:00
parent 89cc852af3
commit 13411853b2
1 changed files with 4 additions and 46 deletions
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50
lisp/emacs-lisp/pcase.el
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@ -105,8 +105,6 @@
specs)))))
(edebug-match cursor (cons '&or specs))))
(fset 'pcase--canon #'identity)
;;;###autoload
(defmacro pcase (exp &rest cases)
"Evaluate EXP and attempt to match it against structural patterns.
@ -334,8 +332,7 @@ any kind of error."
;; to a separate function if that number is too high.
;;
;; We've already used this branch. So it is shared.
(let* (;; (code (car prev))
(cdrprev (cdr prev))
(let* ((code (car prev)) (cdrprev (cdr prev))
(prevvars (car cdrprev)) (cddrprev (cdr cdrprev))
(res (car cddrprev)))
(unless (symbolp res)
@ -437,10 +434,8 @@ to this macro."
;; Don't use let*, otherwise macroexp-let* may merge it with some surrounding
;; let* which might prevent the setcar/setcdr in pcase--expand's fancy
;; codegen from later metamorphosing this let into a funcall.
(if vars
`(let ,(mapcar (lambda (b) (list (car b) (cdr b))) vars)
,@code)
`(progn ,@code)))
`(let ,(mapcar (lambda (b) (list (car b) (cdr b))) vars)
,@code))
(defun pcase--small-branch-p (code)
(and (= 1 (length code))
@ -456,36 +451,7 @@ to this macro."
(cond
((eq else :pcase--dontcare) then)
((eq then :pcase--dontcare) (debug) else) ;Can/should this ever happen?
;; FIXME: The code below shows that there are some opportunities for sharing,
;; but it's rarely useful to do it here, since almost all sharing found
;; shares a trivial expression.
;; But among the common trivial expressions are those of the form
;; (funcall pcase-0). For this case, there could be a significant payoff
;; if we could find the sharing-opportunity earlier so as to avoid
;; the creation of pcase-0.
;; ((and (eq 'if (car-safe then))
;; (equal (macroexp-unprogn (macroexp-progn (nthcdr 3 then)))
;; (macroexp-unprogn else)))
;; (let ((res (macroexp-if `(and ,test ,(nth 1 then))
;; (nth 2 then) else)))
;; (message "if+if => if-and: sharing %S" else)
;; res))
;; ((and (eq 'if (car-safe else))
;; (equal (nth 2 else) then))
;; (let ((res (macroexp-if `(or ,test ,(nth 1 else))
;; then (macroexp-progn (nthcdr 3 else)))))
;; (message "if+if => if-or: sharing %S" then)
;; res))
(t
;; (cond
;; ((and (eq 'cond (car-safe then))
;; (equal `(cond ,@(nthcdr 2 then)) else))
;; (message "if+cond => cond-and: sharing %S" else))
;; ((and (eq 'cond (car-safe else))
;; (equal (macroexp-unprogn (macroexp-progn (cdr (nth 1 else))))
;; (macroexp-unprogn then)))
;; (message "if+cond => cond-or: sharing %S" then)))
(macroexp-if test then else))))
(t (macroexp-if test then else))))
;; Note about MATCH:
;; When we have patterns like `(PAT1 . PAT2), after performing the `consp'
@ -953,14 +919,6 @@ QPAT can take the following forms:
((or (stringp qpat) (integerp qpat) (symbolp qpat)) `',qpat)
(t (error "Unknown QPAT: %S" qpat))))
;;; Extra definitions that use pcase.
(defun pcase--canon (e)
(pcase e
(`(progn ,e) (pcase--canon e))
(`(cond (,test . ,then) (t . ,else))
`(if ,test ,(macroexp-progn then) ,(macroexp-progn else)))))
(provide 'pcase)
;;; pcase.el ends here