csg_parser is a library for parsing an OpenSCAD .csg file and converting it to .xcsg format.
Normally, the xcsg application is called with an .xcsg input file, generated by the AngelCAD script compiler as_csg:
$ as_csg inputfile.as
$ xcsg --stl inputfile.xcsg
The csg_parser library is integrated into the xcsg application, so it is also possible to use an OpenSCAD .csg input file:
$ xcsg --stl inputfile.csg
Given an OpenSCAD inputfile.scad file, it must first be converted to .csg using OpenSCAD:
$ openscad inputfile.scad --o inputfile.csg
$ xcsg --stl inputfile.csg