asciidoc.py 文件源码

def literal_eval(node_or_string):
        """
        Safely evaluate an expression node or a string containing a Python
        expression.  The string or node provided may only consist of the
        following Python literal structures: strings, numbers, tuples,
        lists, dicts, booleans, and None.
        """
        _safe_names = {'None': None, 'True': True, 'False': False}
        if isinstance(node_or_string, basestring):
            node_or_string = compiler.parse(node_or_string, mode='eval')
        if isinstance(node_or_string, Expression):
            node_or_string = node_or_string.node
        def _convert(node):
            if isinstance(node, Const) and isinstance(node.value,
                    (basestring, int, float, long, complex)):
                 return node.value
            elif isinstance(node, Tuple):
                return tuple(map(_convert, node.nodes))
            elif isinstance(node, compiler.ast.List):
                return list(map(_convert, node.nodes))
            elif isinstance(node, Dict):
                return dict((_convert(k), _convert(v)) for k, v
                            in node.items)
            elif isinstance(node, Name):
                if node.name in _safe_names:
                    return _safe_names[node.name]
            elif isinstance(node, UnarySub):
                return -_convert(node.expr)
            raise ValueError('malformed string')
        return _convert(node_or_string)