emacs: Add 'guix-alist-put'.

* emacs/guix-utils.el (guix-alist-put, guix-alist-put-1)
  (guix-alist-put!): New procedures.
This commit is contained in:
Alex Kost 2015-11-19 01:17:32 +03:00
parent 4ba476f949
commit d9c9f9a515

View file

@ -307,7 +307,7 @@ Example:
,@body)))
;;; Alist accessors
;;; Alist procedures
(defmacro guix-define-alist-accessor (name assoc-fun)
"Define NAME function to access alist values using ASSOC-FUN."
@ -325,6 +325,48 @@ accessed with KEYS."
(guix-define-alist-accessor guix-assq-value assq)
(guix-define-alist-accessor guix-assoc-value assoc)
(defun guix-alist-put (value alist &rest keys)
"Put (add or replace if exists) VALUE to ALIST using KEYS.
Return the new alist.
ALIST is alist of alists of alists ... which can be consecutively
accessed with KEYS.
Example:
(guix-alist-put
'foo
'((one (a . 1) (b . 2))
(two (m . 7) (n . 8)))
'one 'b)
=> ((one (a . 1) (b . foo))
(two (m . 7) (n . 8)))"
(or keys (error "Keys should be specified"))
(guix-alist-put-1 value alist keys))
(defun guix-alist-put-1 (value alist keys)
"Subroutine of `guix-alist-put'."
(cond
((null keys)
value)
((null alist)
(list (cons (car keys)
(guix-alist-put-1 value nil (cdr keys)))))
((eq (car keys) (caar alist))
(cons (cons (car keys)
(guix-alist-put-1 value (cdar alist) (cdr keys)))
(cdr alist)))
(t
(cons (car alist)
(guix-alist-put-1 value (cdr alist) keys)))))
(defun guix-alist-put! (value variable &rest keys)
"Modify alist VARIABLE (symbol) by putting VALUE using KEYS.
See `guix-alist-put' for details."
(set variable
(apply #'guix-alist-put value (symbol-value variable) keys)))
;;; Diff