ruby-bindgen

https://github.com/ruby-rice/ruby-bindgen

ruby-bindgen reads C and C++ headers with libclang and emits Ruby bindings. It supports three output formats: Rice C++ source for high-fidelity C++ wrappers, raw FFI for plain C libraries, and CMake build files to compile the generated extensions. Bindings are driven from a YAML configuration that controls header matching, symbol filtering, name mapping, and version guards. Battle-tested against OpenCV (thousands of classes) and PROJ.