class Opal::Rewriters::PatternMatching

def single_case_match(from, *cases, els)
  cas = cases.shift
  pat, if_guard, body = *cas
  pat = convert_full_pattern(from, pat)
  if if_guard
    guard, = *if_guard
    case if_guard.type
    when :if_guard
      pat = s(:and, pat, guard)
    when :unless_guard
      pat = s(:and, pat, s(:send, guard, :!))
    end
  end
  s(:if,
    pat,
    process(body),
    if !cases.empty?
      single_case_match(from, *cases, els)
    elsif els != s(:empty_else)
      els
    end
  )
end