nixpkgs/pkgs/applications/editors/emacs/build-support/buffer.nix
Anderson Torres 368f163caa emacs: migrate build-support/emacs to applications/editors/emacs/build-support
As a consequence of restrictions imposed by RFC 140 - Simple Package Paths [1]
-, files related to a package should be confined on the package directory.

Certainly this restriction does not apply to packages outside by-name hierarchy.

Nonetheless, this is an interesting organization heuristics: things that affect
Emacs should be confined inside Emacs directory. Besides a future migration, the
"debuggability" of a framework is way more enhanced when we know how to find all
its files.

A similar task was done before, when RFC 140 was not a thging yet - namely, the
migration of emacs-modes to elisp-packages [2].

[1] https://github.com/NixOS/rfcs/pull/140
[2] https://github.com/NixOS/nixpkgs/pull/123859
2024-07-06 09:41:13 -03:00

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Nix

# Functions to build elisp files to locally configure emcas buffers.
# See https://github.com/shlevy/nix-buffer
{ lib, writeText, inherit-local }:
rec {
withPackages = pkgs': let
pkgs = builtins.filter (x: x != null) pkgs';
extras = map (x: x.emacsBufferSetup pkgs) (builtins.filter (builtins.hasAttr "emacsBufferSetup") pkgs);
in writeText "dir-locals.el" ''
(require 'inherit-local "${inherit-local}/share/emacs/site-lisp/elpa/inherit-local-${inherit-local.version}/inherit-local.elc")
; Only set up nixpkgs buffer handling when we have some buffers active
(defvar nixpkgs--buffer-count 0)
(when (eq nixpkgs--buffer-count 0)
(make-variable-buffer-local 'nixpkgs--is-nixpkgs-buffer)
; When generating a new temporary buffer (one whose name starts with a space), do inherit-local inheritance and make it a nixpkgs buffer
(defun nixpkgs--around-generate (orig name &optional ibh)
(if (and nixpkgs--is-nixpkgs-buffer (eq (aref name 0) ?\s))
(let ((buf (funcall orig name ibh)))
(progn
(inherit-local-inherit-child buf)
(with-current-buffer buf
(setq nixpkgs--buffer-count (1+ nixpkgs--buffer-count))
(add-hook 'kill-buffer-hook 'nixpkgs--decrement-buffer-count nil t)))
buf)
(funcall orig name ibh)))
(advice-add 'generate-new-buffer :around #'nixpkgs--around-generate)
; When we have no more nixpkgs buffers, tear down the buffer handling
(defun nixpkgs--decrement-buffer-count ()
(setq nixpkgs--buffer-count (1- nixpkgs--buffer-count))
(when (eq nixpkgs--buffer-count 0)
(advice-remove 'generate-new-buffer #'nixpkgs--around-generate)
(fmakunbound 'nixpkgs--around-generate)
(fmakunbound 'nixpkgs--decrement-buffer-count))))
(setq nixpkgs--buffer-count (1+ nixpkgs--buffer-count))
(add-hook 'kill-buffer-hook 'nixpkgs--decrement-buffer-count nil t)
; Add packages to PATH and exec-path
(make-local-variable 'process-environment)
(put 'process-environment 'permanent-local t)
(inherit-local 'process-environment)
; setenv modifies in place, so copy the environment first
(setq process-environment (copy-tree process-environment))
(setenv "PATH" (concat "${lib.makeSearchPath "bin" pkgs}:" (getenv "PATH")))
(inherit-local-permanent exec-path (append '(${builtins.concatStringsSep " " (map (p: "\"${p}/bin\"") pkgs)}) exec-path))
(inherit-local-permanent eshell-path-env (concat "${lib.makeSearchPath "bin" pkgs}:" (if (boundp 'eshell-path-env) eshell-path-env (getenv "PATH"))))
(setq nixpkgs--is-nixpkgs-buffer t)
(inherit-local 'nixpkgs--is-nixpkgs-buffer)
${lib.concatStringsSep "\n" extras}
'';
# nix-buffer function for a project with a bunch of haskell packages
# in one directory
haskellMonoRepo = { project-root # The monorepo root
, haskellPackages # The composed haskell packages set that contains all of the packages
}: { root }:
let # The haskell paths.
haskell-paths = lib.filesystem.haskellPathsInDir project-root;
# Find the haskell package that the 'root' is in, if any.
haskell-path-parent =
let filtered = builtins.filter (name:
lib.hasPrefix (toString (project-root + "/${name}")) (toString root)
) (builtins.attrNames haskell-paths);
in
if filtered == [] then null else builtins.head filtered;
# We're in the directory of a haskell package
is-haskell-package = haskell-path-parent != null;
haskell-package = haskellPackages.${haskell-path-parent};
# GHC environment with all needed deps for the haskell package
haskell-package-env =
builtins.head haskell-package.env.nativeBuildInputs;
in
lib.optionalAttrs is-haskell-package (withPackages [ haskell-package-env ]);
}