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-rw-r--r--emacs/guix-utils.el44
1 files changed, 43 insertions, 1 deletions
diff --git a/emacs/guix-utils.el b/emacs/guix-utils.el
index 3748350b87..fbe0a613da 100644
--- a/emacs/guix-utils.el
+++ b/emacs/guix-utils.el
@@ -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