在LEX中，如何解析某些代码，直到出现特殊符号? [英] In LEX, how to parse some code until a special symbol?

问题描述

我想知道在LEX中是否要解析一些代码直到出现特殊符号.

I was wondering that in LEX, if i want to parse some code until a special symbol.

例如:$display("Hello World");

在这里，我想获取$display("Hello World")，但;除外.

Here, I want to get $display("Hello World") but except ;.

我已经尝试过:\$"display".*[^;]，它似乎没有用.

I've already tried this: \$"display".*[^;], it didn't seem to work.

任何帮助将不胜感激.谢谢.

Any help will be appreciated. Thanks.

推荐答案

.匹配任何字符，而Kleene star *将匹配其前面的许多字符.在这种情况下，您要匹配display，后跟任何其他字符的列表.碰巧会包含您要捕获的位以及分号.

. matches any character, and the Kleene star * will match many of whatever precedes it. In this case, you're matching display followed by a list of any other character. That'll happen to include the bit you want to capture and also the semicolon.

一个明显的解决方法是删除表达式的该部分，并将Kleene星移到[^;]表达式之后.它将说匹配不是;的任何字符的多个实例".这可能需要在子表达式周围加上括号(我不记得prices语法，因为它在词法分析器之间会有所不同).

Obvious fix is to remove that part of the expression, and move the Kleene star to after the [^;] expression. Which will say "match multiple instances of any character which is not ;". This might need parens around the sub-expression (I can't remember pricese syntax as it varies between lexers).

\$"display"([^;])*或\$"display"[^;]*

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