checker.py 文件源码

def TUPLE(self, node):
        if not PY2 and isinstance(node.ctx, ast.Store):
            # Python 3 advanced tuple unpacking: a, *b, c = d.
            # Only one starred expression is allowed, and no more than 1<<8
            # assignments are allowed before a stared expression. There is
            # also a limit of 1<<24 expressions after the starred expression,
            # which is impossible to test due to memory restrictions, but we
            # add it here anyway
            has_starred = False
            star_loc = -1
            for i, n in enumerate(node.elts):
                if isinstance(n, ast.Starred):
                    if has_starred:
                        self.report(messages.TwoStarredExpressions, node)
                        # The SyntaxError doesn't distinguish two from more
                        # than two.
                        break
                    has_starred = True
                    star_loc = i
            if star_loc >= 1 << 8 or len(node.elts) - star_loc - 1 >= 1 << 24:
                self.report(messages.TooManyExpressionsInStarredAssignment, node)
        self.handleChildren(node)