yacc可以识别出记号的模式；例如，如上面例子中所示，它可以识别出一个表达式可能由一个值、一个加号或者减号以及另一个值构成。
Yacc can recognize patterns of tokens; for instance, as in the example above, it can recognize that an expression can consist of a value, either a plus or minus sign, and another value.
TOKEN语句包含类似 regex 的表达式，该表达式描述了整数记号看起来象什么。
The TOKEN statement contains a regex-like expression that describes what integer tokens look like.
计量符可以在Spark记号赋予器(tokenizer)的正则表达式中使用，并可以用解析表达式语法中的递归来进行模拟。
Quantifiers can be used within the regular expressions of the Spark tokenizer, and can be simulated by recursion in parse expression grammars.
如果解析器在其扫描期间发现了除这三个记号外的任何其它记号，则认为它正在扫描的表达式是无效的。
If the parser finds anything other than these three tokens during its scan, the expression it's scanning is considered invalid.
如果解析器在其扫描期间发现了除这三个记号外的任何其它记号，则认为它正在扫描的表达式是无效的。
If the parser finds anything other than these three tokens during its scan, the expression it's scanning is considered invalid.
应用推荐