Add support nix 2.4 flakes in search

This lets you search flakes like so:

M-x nix-search<RET>
abc

Author: matthewbauer

nix-search.el

@@ -17,24 +17,29 @@
 (require 'json)
 
 ;;;###autoload
-(defun nix-search--search (search file &optional no-cache)
+(defun nix-search--search (search file &optional no-cache use-flakes)
   (with-temp-buffer
-    (call-process nix-executable nil (list t nil) nil
-      "search" "--json" (if no-cache "--no-cache" "") "--file" file search)
+    (if use-flakes
+	(call-process nix-executable nil (list t nil) nil
+		      "search" "--json" file (if (string= search "") "." search))
+      (call-process nix-executable nil (list t nil) nil
+		    "search" "--json" (if no-cache "--no-cache" "") "--file" file search))
     (goto-char (point-min))
     (json-read)))
 
 ;;;###autoload
-(defun nix-search--display (results &optional display-buffer)
+(defun nix-search--display (results &optional display-buffer use-flakes)
   (unless display-buffer (setq display-buffer (generate-new-buffer "*nix search*")))
   (with-current-buffer display-buffer
     (dolist (entry results)
       (widget-insert
-        (format "attr: %s\nname: %s\nversion: %s\ndescription: %s\n\n"
-          (car entry)
-          (alist-get 'pkgName (cdr entry))
-          (alist-get 'version (cdr entry))
-          (alist-get 'description (cdr entry))))))
+       (format "attr: %s\nname: %s\nversion: %s\ndescription: %s\n\n"
+               (car entry)
+               (if use-flakes
+		   (alist-get 'pname (cdr entry))
+		 (alist-get 'pkgName (cdr entry)))
+               (alist-get 'version (cdr entry))
+               (alist-get 'description (cdr entry))))))
   (display-buffer display-buffer))
 
 ;;;###autoload
@@ -43,10 +48,11 @@
 SEARCH a search term to use.
 FILE a Nix expression to search in."
   (interactive "snix-search> \n")
-  (setq file (or file (nix-read-file)))
-  (let ((results (nix-search--search search file)))
+  (setq use-flakes (nix-has-flakes))
+  (setq file (or file (if use-flakes (nix-read-flake) (nix-read-file))))
+  (let ((results (nix-search--search search file nil use-flakes)))
     (when (called-interactively-p 'any)
-      (nix-search--display results))
+      (nix-search--display results nil use-flakes))
     results))
 
 (defun nix-search-read-attr (file)

nix-shell.el

@@ -60,6 +60,12 @@ Should only be set in dir-locals.el file."
   :type 'stringp
   :group 'nix-shell)
 
+(defcustom nix-flake nil
+  "Nix flake to build expressions from.
+Should only be set in dir-locals.el file."
+  :type 'stringp
+  :group 'nix-shell)
+
 (defcustom nix-attr nil
   "Nix attribute path to use.
 Should only be set in dir-locals.el file."
@@ -80,6 +86,13 @@ ATTR is the attribute to unpack."
   "Get nix attribute from user."
   (read-string "Nix attr: "))
 
+(defun nix-read-flake ()
+  "Get nix flake from user."
+  (cond
+   (nix-flake nix-flake)
+   ((and (nix-has-flakes) (file-exists-p "flake.nix")) ".")
+   (t (read-string "Nix flake: " "nixpkgs"))))
+
 (defun nix-read-file ()
   "Get nix file from user."
   (cond

nix.el

@@ -78,6 +78,17 @@
       (kill-buffer stdout)
       result)))
 
+(defun nix-show-config ()
+  "Show nix config."
+  (let ((stdout (generate-new-buffer "nix config"))
+        result)
+    (call-process nix-executable nil (list stdout nil) nil "show-config" "--json")
+    (setq result (with-current-buffer stdout
+	           (goto-char (point-min))
+	           (json-read)))
+    (kill-buffer stdout)
+    result))
+
 (defvar nix-commands
   '("add-to-store"
     "build"
@@ -187,10 +198,23 @@ OPTIONS a list of options to accept."
        ((or (string= "-s" last-arg) (string= "--substituter" last-arg))
         (pcomplete-here))))))
 
+(defun nix-is-24 ()
+  "Whether Nix is a version with Flakes support."
+  ;; earlier versions reported as 3, now it’s just nix-2.4
+  (let ((version (nix-version)))
+    (or (string-prefix-p "nix (Nix) 3" version)
+        (string-prefix-p "nix (Nix) 2.4" version))))
+
+(defun nix-has-flakes ()
+  "Whether Nix is a version with Flakes support."
+  ;; earlier versions reported as 3, now it’s just nix-2.4
+  (and (nix-is-24)
+       (seq-contains-p (alist-get 'value (alist-get 'experimental-features (nix-show-config))) "flakes")))
+
 ;;;###autoload
 (defun pcomplete/nix ()
   "Completion for the nix command."
-  (if (string-prefix-p "nix (Nix) 3" (nix-version))
+  (if (nix-is-24)
       (let ((stdout (generate-new-buffer "nix-completions"))
             (process-environment
              (cons (format "NIX_GET_COMPLETIONS=%s" (1- (length pcomplete-args)))