walker.py 文件源码

def _walk_fields(self, state, node, ctx):
        """
        Traverses all fields of an AST node.
        """
        if self._transform:
            transformed = False
            new_fields = {}

        new_state = state
        for field, value in ast.iter_fields(node):

            block_context = field in _BLOCK_FIELDS and type(value) == list
            new_state, new_value = self._walk_field(
                new_state, value, ctx, block_context=block_context)

            if self._transform:
                new_fields[field] = new_value
                if new_value is not value:
                    transformed = True

        if self._transform and transformed:
            return new_state, type(node)(**new_fields)
        else:
            return new_state, node