module Concurrent::Utility::EngineDetector

def on_cruby?
  ruby_engine == 'ruby'
end

def on_jruby?
  ruby_engine == 'jruby'
end

def on_jruby_9000?
  on_jruby? && ruby_version(JRUBY_VERSION, :>=, 9, 0, 0)
end

def on_linux?
  !(RbConfig::CONFIG['host_os'] =~ /linux/).nil?
end

def on_osx?
  !(RbConfig::CONFIG['host_os'] =~ /darwin|mac os/).nil?
end

def on_rbx?
  ruby_engine == 'rbx'
end

def on_truffleruby?
  ruby_engine == 'truffleruby'
end

def on_windows?
  !(RbConfig::CONFIG['host_os'] =~ /mswin|mingw|cygwin/).nil?
end

def ruby_engine
  defined?(RUBY_ENGINE) ? RUBY_ENGINE : 'ruby'
end

def ruby_version(version = RUBY_VERSION, comparison, major, minor, patch)
  result      = (version.split('.').map(&:to_i) <=> [major, minor, patch])
  comparisons = { :== => [0],
                  :>= => [1, 0],
                  :<= => [-1, 0],
                  :>  => [1],
                  :<  => [-1] }
  comparisons.fetch(comparison).include? result
end