environment.py 文件源码

def process_only_nodes(self, doctree, builder, fromdocname=None):
        # A comment on the comment() nodes being inserted: replacing by [] would
        # result in a "Losing ids" exception if there is a target node before
        # the only node, so we make sure docutils can transfer the id to
        # something, even if it's just a comment and will lose the id anyway...
        for node in doctree.traverse(addnodes.only):
            try:
                ret = builder.tags.eval_condition(node['expr'])
            except Exception as err:
                self.warn_node('exception while evaluating only '
                               'directive expression: %s' % err, node)
                node.replace_self(node.children or nodes.comment())
            else:
                if ret:
                    node.replace_self(node.children or nodes.comment())
                else:
                    node.replace_self(nodes.comment())