[nongnu] elpa/nix-mode a4e6560902 223/500: Add nix-instantiate.el

[ELPA Syncer]

branch: elpa/nix-mode
commit a4e65609023f1d06a76f7a75716d860bd27cfb68
Author: Matthew Bauer <matthew.bauer@obsidian.systems>
Commit: Matthew Bauer <matthew.bauer@obsidian.systems>

    Add nix-instantiate.el
---
 nix-instantiate.el | 100 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 100 insertions(+)

diff --git a/nix-instantiate.el b/nix-instantiate.el
new file mode 100644
index 0000000000..25dbcca8da
--- /dev/null
+++ b/nix-instantiate.el
@@ -0,0 +1,100 @@
+;;; nix-instantiate.el -- run nix commands in Emacs -*- lexical-binding: t -*-
+
+;; Author: Matthew Bauer <mjbauer95@gmail.com>
+;; Homepage: https://github.com/NixOS/nix-mode
+;; Keywords: nix
+
+;; This file is NOT part of GNU Emacs.
+
+;;; Commentary:
+
+;;; Code:
+
+(require 'nix)
+(require 'json)
+
+(defun nix-instantiate--parsed (drv)
+  "Get the parsed version of the .drv file.
+DRV file to load from."
+  (let ((stdout (generate-new-buffer "nix show-derivation")))
+    (call-process nix-executable nil (list stdout nil) nil
+                 "show-derivation" drv)
+    (cdar (with-current-buffer stdout
+           (when (eq (buffer-size) 0)
+             (error
+              "Error: nix show-derivation %s failed to produce any output"
+              drv))
+           (goto-char (point-min))
+           (json-read)))))
+
+;;;###autoload
+(defun nix-instantiate (nix-file &optional attribute)
+  "Run nix-instantiate on a Nix expression.
+NIX-FILE the file to instantiate.
+ATTRIBUTE an attribute of the Nix file to use."
+  (interactive "fNix file: ")
+  (setq nix-file (expand-file-name nix-file))
+  (let ((stdout (generate-new-buffer "nix-instantiate"))
+       result)
+    (if attribute
+       (call-process nix-instantiate-executable nil (list stdout nil) nil
+                     nix-file "-A" attribute)
+      (call-process nix-instantiate-executable nil (list stdout nil) nil
+                   nix-file))
+    (with-current-buffer stdout
+      (when (eq (buffer-size) 0)
+       (error
+        "Error: nix-instantiate %s failed to produce any output"
+        nix-file))
+      (setq result (nix-instantiate--parsed
+                   (substring (buffer-string) 0 (- (buffer-size) 1)))))
+    (kill-buffer stdout)
+    result))
+
+(defvar nix-instantiate--running-processes nil)
+
+(defun nix-instantiate--sentinel (prop err proc event)
+  "Make a nix-instantiate process.
+PROP the prop name of nix-instantiate--running-processes.
+ERR the error buffer.
+PROC the process that has been run.
+EVENT the event that was fired."
+  (when (string= event "finished\n")
+    (with-current-buffer (process-buffer proc)
+      (unless (eq (buffer-size) 0)
+       (let ((drv (nix-instantiate--parsed
+                   (substring (buffer-string) 0 (- (buffer-size) 1)))))
+         (dolist
+             (callback (lax-plist-get nix-instantiate--running-processes prop))
+           (funcall callback drv)))))
+    (setq nix-instantiate--running-processes
+         (lax-plist-put nix-instantiate--running-processes prop nil))
+    (kill-buffer (process-buffer proc))
+    (kill-buffer err)))
+
+;;;###autoload
+(defun nix-instantiate-async (callback nix-file &optional attribute)
+  "Run nix-instantiate on a Nix expression, asynchronously.
+CALLBACK the function to call when instantiate completes.
+NIX-FILE the file to instantiate
+ATTRIBUTE an attribute of the Nix file to use."
+  (setq nix-file (expand-file-name nix-file))
+  (let* ((prop (if attribute
+                  (expand-file-name attribute nix-file) nix-file))
+        (data (lax-plist-get nix-instantiate--running-processes prop))
+        (stdout (generate-new-buffer "nix-instantiate"))
+        (stderr (generate-new-buffer "nix-instantiate error")))
+    (setq nix-instantiate--running-processes
+         (lax-plist-put nix-instantiate--running-processes
+                        prop (cons callback data)))
+    (make-process
+     :name "nix-instantiate"
+     :buffer stdout
+     :command (append (list nix-instantiate-executable nix-file)
+                     (when attribute ("-A" attribute)))
+     :noquery t
+     :sentinel (apply-partially 'nix-instantiate--sentinel prop stderr)
+     :stderr stderr)))
+
+(provide 'nix-instantiate)
+;;; nix-instantiate.el ends here