example3.py 文件源码

def visit(self, node):
        stack = [ Visit(node) ]
        last_result = None
        while stack:
            try:
                last = stack[-1]
                if isinstance(last, types.GeneratorType):
                    stack.append(last.send(last_result))
                    last_result = None
                elif isinstance(last, Visit):
                    stack.append(self._visit(stack.pop().node))
                else:
                    last_result = stack.pop()
            except StopIteration:
                stack.pop()
        return last_result