[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: Using gv in map and seq?
From: |
Stefan Monnier |
Subject: |
Re: Using gv in map and seq? |
Date: |
Mon, 15 Jun 2015 12:30:03 -0400 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/25.0.50 (gnu/linux) |
>>> I was wondering if it would make sense to use gv in map or seq?
>> Not sure what you mean. Do you mean to add a setter for seq-elt?
> Yes
I see. Yes, defining a "gv-setter" or "gv-expander" would be good.
Oh, wait, no, it's not needed, since seq-elt is an alias for `elt' and
that one already has a setter. IOW it already works!
> (and a getter too?).
When defining a setter, you need to define the getter as well, indeed, but
that's generally the trivial part.
> The same goes for `map-elt'.
This one is not pre-defined, so yes, we should define it.
Actually, this just means to turn map-put into a gv-setter.
Something like the patch below seems to work (and it generalizes
map-put to accept for MAP not only symbols but any "lvalue"). It also
tightens the code generated by map--dispatch.
Stefan
diff --git a/lisp/emacs-lisp/map.el b/lisp/emacs-lisp/map.el
index dd7fb91..26ad6ce 100644
--- a/lisp/emacs-lisp/map.el
+++ b/lisp/emacs-lisp/map.el
@@ -82,25 +82,19 @@ The following keyword types are meaningful: `:list',
An error is thrown if MAP is neither a list, hash-table nor array.
-Return RESULT if non-nil or the result of evaluation of the
-form.
+Return RESULT if non-nil or the result of evaluation of the form.
\(fn (VAR MAP [RESULT]) &rest ARGS)"
(declare (debug t) (indent 1))
(unless (listp spec)
(setq spec `(,spec ,spec)))
- (let ((map-var (car spec))
- (result-var (make-symbol "result")))
- `(let ((,map-var ,(cadr spec))
- ,result-var)
- (setq ,result-var
- (cond ((listp ,map-var) ,(plist-get args :list))
- ((hash-table-p ,map-var) ,(plist-get args :hash-table))
- ((arrayp ,map-var) ,(plist-get args :array))
- (t (error "Unsupported map: %s" ,map-var))))
- ,@(when (cddr spec)
- `((setq ,result-var ,@(cddr spec))))
- ,result-var)))
+ (let ((map-var (car spec)))
+ `(let* ,(unless (eq map-var (cadr spec)) `((,map-var ,(cadr spec))))
+ (cond ((listp ,map-var) ,(plist-get args :list))
+ ((hash-table-p ,map-var) ,(plist-get args :hash-table))
+ ((arrayp ,map-var) ,(plist-get args :array))
+ (t (error "Unsupported map: %s" ,map-var)))
+ ,@(cddr spec))))
(defun map-elt (map key &optional default)
"Perform a lookup in MAP of KEY and return its associated value.
@@ -109,27 +103,23 @@ If KEY is not found, return DEFAULT which defaults to nil.
If MAP is a list, `equal' is used to lookup KEY.
MAP can be a list, hash-table or array."
+ (declare
+ (gv-expander
+ (lambda (do)
+ (macroexp-let2* nil
+ ;; Eval them once and for all in the right order.
+ ((map map) (key key) (default default))
+ `(map--dispatch map
+ :list ,(gv-get `(alist-get ,key ,map ,default) do)
+ :hash-table ,(funcall do `(gethash ,key ,map ,default)
+ (lambda (v) `(puthash ,key ,v ,map)))
+ :array ,(funcall do `(aref ,map ,key)
+ (lambda (v) `(aset ,map ,key ,v))))))))
(map--dispatch map
:list (map--elt-list map key default)
:hash-table (gethash key map default)
:array (map--elt-array map key default)))
-(defmacro map-put (map key value)
- "In MAP, associate KEY with VALUE and return MAP.
-If KEY is already present in MAP, replace the associated value
-with VALUE.
-
-MAP can be a list, hash-table or array."
- (declare (debug t))
- (let ((symbol (symbolp map)))
- `(progn
- (map--dispatch (m ,map m)
- :list (if ,symbol
- (setq ,map (cons (cons ,key ,value) m))
- (error "Literal lists are not allowed, %s must be a symbol"
',map))
- :hash-table (puthash ,key ,value m)
- :array (aset m ,key ,value)))))
-
(defmacro map-delete (map key)
"In MAP, delete the key KEY if present and return MAP.
If MAP is an array, store nil at the index KEY.
- Using gv in map and seq?, Nicolas Petton, 2015/06/15
- Re: Using gv in map and seq?, Stefan Monnier, 2015/06/15
- Re: Using gv in map and seq?, Nicolas Petton, 2015/06/15
- Re: Using gv in map and seq?,
Stefan Monnier <=
- Re: Using gv in map and seq?, Stefan Monnier, 2015/06/15
- Re: Using gv in map and seq?, Nicolas Petton, 2015/06/16
- Re: Using gv in map and seq?, Nicolas Petton, 2015/06/16
- Re: Using gv in map and seq?, Stefan Monnier, 2015/06/16
- Re: Using gv in map and seq?, Stefan Monnier, 2015/06/17
- Re: Using gv in map and seq?, Nicolas Petton, 2015/06/17
- Re: Using gv in map and seq?, Stefan Monnier, 2015/06/17
- Re: Using gv in map and seq?, Nicolas Petton, 2015/06/18
- Re: Using gv in map and seq?, Stefan Monnier, 2015/06/18
- Re: Using gv in map and seq?, Nicolas Petton, 2015/06/16