fork cheap gen

Headers = []

at_exit {
    code = []
    Headers.each{|x| code << "#include <#{x}.h>" }
    code << "int main() {"
    Stack.each{|x|
        code << "#{make_indent}#{x};"
    }
    code << "  return 0;"
    code << "}"
    puts code
    open('a.c', 'w') {|f| f.puts code }
    puts "---------------------------"
    system 'gcc -w -lm a.c && ./a.out'
}

Pos = :__pos__

@indent = 2
def make_indent
   " " * @indent
end

Stack = []

def double(name = fresh, value = 0)
    Stack.push "double #{name} = #{value}"
    name.to_sym
end

class T
    def self.fresh
       @id ||= 0
       @id += 1
       "v_#{@id}"
    end
    def method_missing(type, name = T.fresh, value = 0)
        if Numeric === name
            name, value = T.fresh, name
        end
        Stack.push "#{type} #{name} = #{value}"
        name.to_sym
    end
end

t = T.new

def getargs(*args)
    args.reverse.map{|x|
        case x
        when Pos
            Stack.pop
        when String
            x.inspect
        else
            x
        end
    }.reverse
end

def ref(a)
   r = getargs(a)
   Stack.push "&#{r[0]}"
   Pos
end

class O
  def method_missing(sym, *args)
     a = getargs(*args)
     Stack.push("((#{a.join(") #{sym} (")}))")    
     Pos
  end
end

o = O.new

class D
  def method_missing(sym, *args)
     a = getargs(*args)
     Stack.push("#{sym}(#{a.join(", ")})")    
     Pos
  end
end

class C
  def method_missing(sym, *)
      Headers.push(sym) unless Headers.include?(sym)
      ::D.new
  end
end

c = C.new

c.stdio.printf("%lf", o.+(c.math.sqrt((a = t.double 2)), a))