os: osx
osx_image:
  - xcode11
  - xcode12
  - xcode12.5
language: cpp
compiler: clang
before_script: 
  - mkdir build
  - cd build
  - cmake ..
script: make mpw
before_install:
  - brew update
  - brew install lemon
  - brew install ragel
#  - brew install cmake # not needed.