“LBUFFER%%(#m)[_a-zA-Z0-9]#”在zsh中做什么?

I need help understanding what the following code in this documentation means.

我需要帮助理解本文档中下列代码的含义。

LBUFFER=${LBUFFER%%(#m)[_a-zA-Z0-9]#}
LBUFFER+=${abbreviations[$MATCH]:-$MATCH}

I learned that LBUFFER contains the left from the cursor. However, there are 3 things that confuse me.

我了解到LBUFFER包含游标中的左边。然而，有三件事让我困惑。

1. What is the %% doing? Is it escaping %?
2. %在做什么?逃离%吗?
3. What does (#m)[_a-zA-Z0-9]# do? Is it something like m/[_a-zA-Z0-9]/ in Perl? If so, what is done to the matched string?
4. 什么(#)[_a-zA-Z0-9]#做什么?它在Perl中类似于m/[_a-zA-Z0-9]/吗?如果是，那么对匹配的字符串做了什么?
5. What is the :- part doing in the second line?
6. -在第二行做什么?

Thanks.

谢谢。

1 个解决方案

#1

1. ${a%%b} removes the longest occurrence of b (which can be a regular expression), from a.

   ${a% b}从a中删除最长的b(可以是正则表达式)。

2. [_a-zA-Z0-9]# is a regular expression matching an alphanumeric character (as indicated by the stuff between []) zero or more times (specified by the # glob operator)

   [_a-zA-Z0-9]#是一个正则表达式，匹配一个字母数字字符(如[]之间的内容所示)零次或多次(由# glob操作符指定)

3. (#m) populates the $MATCH variable after evaluating the previous regular expression.

   (#m)在计算之前的正则表达式之后填充$MATCH变量。

4. The combination of 1, 2, and 3 means that the stretch of alphanumeric characters at the end of the $LBUFFER is deleted and stored in $MATCH.

   1、2和3的组合意味着$LBUFFER末尾的字母数字字符的扩展被删除并存储在$MATCH中。

5. ${a:-b} makes a equal to b only if a is not defined.

   ${a:-b}只在未定义a时才使a等于b。

If you want to learn more, take a look at the expansion chapter of the zsh manual.

如果您想了解更多，请查看zsh手册的扩展章节。