i3-config-parser is a direct port of the i3wm configuration file parser, which utilizes the spec file from the i3wm source tree (duplicated in the i3-config-parser) source tree.
It is not a particularly elegant implementation at time of initial release; I needed to parse the config file for a bigger project, and this was the most straightforward way to get it done. At the moment it handles most of the major parts of the i3wm config, but I'm 100% certain there are remaining issues. Use at your own risk.