Like any software reading a file, the parser is built around a reading loop: a loop that progresses through the file.

和读取文件的任何软件一样，解析器也是围绕着读循环(读入文件的循环)创建的。

But even with the simplicity of this loop construct, you can build any complex loop.

然而仅仅使用简单的循环结构，您也能构建任意复杂的循环。

This means the program statements executed in the loop body must change the value of the expression — or else the loop will never end.

这意味着循环体中执行的程序语句必须要改变表达式的值，否则循环将无法结束。

In cases where a break combination is part of an alternative or a loop, then only the alternative or loop is exited.

在这种情况下，跳转组合是变体或者循环的一部分，然后只是变体或循环被退出。

The loop in this sequence diagram USES a Boolean test to verify if the loop sequence should be run.

如果循环序列应该运行，这个序列图的循环使用一个布尔测试确认。