[FBT]: Add fbt tool (Fg42 Build Tool) to build FG42

Signed-off-by: Sameer Rahmani <lxsameer@gnu.org>

CONTRIBUTE

@@ -39,6 +39,7 @@ accept code without a proper header file.
 We follow these simple rules:
 
 * Make elisp linter happy
+* Make byte compiler happy `make compile`
 * Follow functional patterns and avoid huge functions
 * Seperate each root level expression by two new lines (e.g function definitions)
 * Put `(comment ...)` expression after each macro/function to demonstrate the usage.
@@ -55,7 +56,9 @@ Submit your contribution against the `master` branch. The `stable` branch
 is going to be our last stable version only.
 
 Please make one PR per feature. Keep your PRs as small as possible so we can review them
-easily.
+easily. Don't forget to make the byte compiler and the linter happy. There should not
+be any build error or warning on `make compile`. We like how [Linus Torvalds thinks
+about build warnings](https://linuxreviews.org/Linus_Torvalds#On_Build-Testing).
 
 Write commit messages according to adapted [this article](https://chris.beams.io/posts/git-commit/):
 

core/fg42/utils.el

@@ -104,8 +104,9 @@ with is the buffer."
 For example for a list like (list :x 4 :y 5) we can find the value of
 `:x' by doing `(get-value-for lst :x)'."
   (let ((pairs (seq-partition lst 2)))
-    (when-let (pair (assq key pairs))
-      (cadr pair))))
+    (let ((pair (assq key pairs)))
+      (when pair
+        (cadr pair)))))
 
 
 (defun comp (&rest fns)

fbt

@@ -0,0 +1,53 @@
+:;exec emacs --no-site-file --no-site-lisp -batch -l "$0" -f main "$@"
+;;; FGBuildTool --- The build tool for FG42
+;;
+;; Copyright (c) 2010-2020  Sameer Rahmani <lxsameer@gnu.org>
+;;
+;; Author: Sameer Rahmani <lxsameer@gnu.org>
+;; URL: https://gitlab.com/FG42/FG42
+;; Version: 3.0.0
+;;
+;; This program is free software; you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+;;
+;; This program is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+;;
+;; You should have received a copy of the GNU General Public License
+;; along with this program.  If not, see <http://www.gnu.org/licenses/>.
+;;
+;;
+;;; Commentary:
+;;; Code:
+
+(defun compile (dir)
+  "Compile all the elisp files in the given DIR regardless of timestamp.
+The DIR should be relative to FG42_HOME."
+  (let ((target (concat (getenv "FG42_HOME") (format "/%s" dir))))
+    (message "Compiling '%s'..." target)
+    (add-to-list 'load-path target)
+    (byte-recompile-directory target 0 t)))
+
+
+(defun build (&rest params)
+  "Compile the core and install the dependencies with the given PARAMS."
+  (compile "core"))
+
+
+(defun main ()
+  "Execute a subcommand by looking into input arguments of the script."
+  (print (version))
+  (let ((command (car command-line-args-left))
+        (args (cdr command-line-args-left)))
+    (cond
+     ((string= command "compile") (funcall #'compile (or (car args) "core")))
+     ((string= command "build") (funcall #'build args)))))
+
+;; Local Variables:
+;; mode: emacs-lisp
+;; End:
+;;; fbt ends here

fg42-new

@@ -1,7 +1,8 @@
 #! /bin/sh
 
-export FG42_HOME=/home/lxsameer/.fg42
-FG42_WM=false /home/lxsameer/src/emacs/build/bin/emacs --name FG42 \
+export FG42_HOME="$( cd "$(dirname "$0")" >/dev/null 2>&1 ; pwd -P )"
+
+FG42_WM=false emacs --name FG42 \
               --no-site-file --no-site-lisp --no-splash --title FG42 \
               -L $FG42_HOME/core \
               -L $FG42_HOME/extensions \