SSCCPP, the Simple Switch Cases Configuration PreProcessor

This small utility makes it easy to have a single file that can be adapted to different cases. Typical use is to manage dotfiles, by allowing to have only one git branch which is then preprocessed before being used as an actual configuration file.

It is written in Rust and provides a library as well as two binaries: ssccpp and ssccpp-batch. ssccpp processes a single file while ssccpp-batch process all files in a directory, copying its structure to an other one.

Concept

ssccpp works on a file where some lines have been turned into switch statements. These switch statements are recognized by looking for a delimiter (by default >>>>>>>> ie. 8 times the '>' character).

A switch block is composed of, in order:

1. One or more "specfic" case(s): >>>>>>>> ident1, ident2, ...
2. One "otherwise" case: >>>>>>>> *
3. And ending delimiter: >>>>>>>>

When reaching such a block, ssccpp will check, for each specific case if one of the ident matches the searched ident (by default the hostname), and if yes, will emit the text that follows. When reaching the otherwise block, it will emit the text that follows if none of the specific statements before were entered. Finally, when reaching the ending delimiter, it will print all following text, until a new block is encountered.

Examples

First example

This line will be displayed everywhere.
>>>>>>>> foo, bar
This line will be displayed on foo and bar only.
>>>>>>>> ga, bu, zo
This line will be displayed on ga, bu and zo, but not foo or bar.
>>>>>>>> foo, zo
This line will be displayed on foo and zo.
>>>>>>>> *
This line will be displayed on anything that is not foo, bar, ga, bu or zo.
>>>>>>>>
This line will be displayed everywhere.

Configuration files example

In this example, the user has a dotfiles directory that mimics the structure of their /home/user directory:

dotfiles/
├── scripts/
│   └── wallpaper.sh
└── .xinitrc

The file content is as follow:

wallpaper.sh

>>>>>>>> laptop
feh --bg-scale 'Images/WallpaperLaptop.png'
>>>>>>>> *
feh --bg-scale 'Images/DefaultWallpaper.png'

.xinitrc

>>>>>>>> desktop
xrandr --dpi 166
>>>>>>>> laptop
xrandr --dpi 96
>>>>>>>>

exec i3

Upon executing ssccpp-batch dotfiles/ /home/user --ident laptop the files will be placed with the same structure in their home directory and become:

wallpaper.sh

feh --bg-scale 'Images/WallpaperLaptop.png'

.xinitrc

xrandr --dpi 96

exec i3

and upon executing ssccpp-batch dotfiles/ /home/user --ident desktop the files will become:

wallpaper.sh

feh --bg-scale 'Images/DefaultWallpaper.png'

.xinitrc

xrandr --dpi 166

exec i3