[X11] Preprocess ./.Xresources when installing

.install.conf.yaml

@@ -27,7 +27,7 @@
     ~/.vimrc: vim/vimrc
     ~/.xinitrc: X11/xinitrc
     ~/.xprofile: X11/xprofile
-    ~/.Xresources: X11/Xresources
+    ~/.Xresources.src: X11/Xresources.src
     ~/.Xresources.d/urxvt: urxvt/Xresources
     ~/.config/user-dirs.dirs: X11/user-dirs.dirs
     ~/.config/awesome: awesome
@@ -37,5 +37,9 @@
     ~/.ssh/keys/:
         mode: 0700
 
-#- shell:
+- shell:
+    -
+      command: ./bin/Xresources-preprocess
+      description: Preprocess Xresources.src so that xrdb doesn't have to.
+      stderr: true
 #   - git submodules update # after linking ~/.gitconfig

bin/Xresources-preprocess

@@ -0,0 +1,45 @@
+#!/bin/sh
+
+# Use the precompiler to allow for `xrdb -nocpp -merge ~/.Xresources`.
+# Inspiration from https://github.com/dolmen/Xresources.edit/blob/1be4f5601b3d4e8befa043386288c64e724ed746/Xresources.edit
+
+fname=.Xresources
+ext=src
+force=
+
+# Initial setup: move $fname to $fname.$ext
+if [ ! -f "$HOME/$fname.$ext" ]; then
+	cat "$HOME/$fname" > "$HOME/$fname.$ext"
+
+	# Make $fname non-writable to discourage direct editing
+	chmod a-wx "$HOME/$fname"
+fi
+
+# Check mtime
+if [ -f "$HOME/$fname" -a "$HOME/$fname" -nt "$HOME/$fname.$ext" ]; then
+	{
+		echo "~/$fname is more recent than ~/$fname.$ext"
+		echo "You have to fix this manually."
+		echo "e.g. touch ~/$fname.$ext"
+	} >&2
+	exit 1
+fi
+
+
+# Run cpp and save the result as ~/$fname
+[ -e "$HOME/$fname" ] && chmod u+w "$HOME/$fname"
+
+{
+	echo '! *************************************************'
+	echo "! Do not edit ~/$fname, but ~/$fname.$ext"
+	echo '! *************************************************'
+	echo '! vim:set ft=xdefaults:'
+	echo '!'
+} > "$HOME/$fname"
+
+cpp "$HOME/$fname.$ext" | tee -a "$HOME/$fname"
+res=$?
+
+# Make $fname non-writable to discourage direct editing
+chmod a-wx "$HOME/$fname"
+exit $res