parser.py 文件源码

def parse_while_loop(self):
        expr = ast.WhileLoop(self.cur_tok, None, None)

        if not self.expect(token.LPAREN):
            return None

        self.next()
        expr.condition = self.parse_expr(LOWEST)

        if not self.expect(token.RPAREN):
            return None

        if not self.expect(token.LBRACE):
            return None

        expr.body = self.parse_block_statement()

        return expr