I'm writing Flex lexer patterns to match a series of commands. Not unlike subversion's command line client, the commands can be shortened to a small but still unambiguous length.
我正在编写与一系列命令匹配的Flex lexer模式。与subversion的命令行客户端相似，命令可以缩短为一个很小但仍然明确的长度。
So a command such as:
因此，命令如下:
MYCOMMAND
Could be entered as either:
也可以输入:
MYCOMMAND
MCOMMAND
MYCOM
MC
The pattern I have been ignorantly writing for these cases looks like:
我一直在不知不觉地为这些案例编写的模式如下:
M(Y)?C(O|OM|OMM|OMMA|OMMAN|OMMAND)?
And it works fine, but it smells pretty bad especially on very long definitions, is there a shorter way of defining such a match?
它运行得很好，但是闻起来很糟糕尤其是在很长的定义上，有更短的方法来定义这样的匹配吗?
2 个解决方案
#1
2
If you can use an end-of-token symbol like $ or \b then you could do:
如果你可以使用象$或\b这样的令牌结尾符号，你可以:
MY?C(O|$)(M|$)(M|$)(A|$)(N|$)(D|$)
#2
1
What about MY?C(O(M(M(A(ND?)?)?)?)?)? ;-)
IMHO, this is the only other way to write it.
关于我的什么? C(O(M(M((ND)?)?)?)吗?)?这是唯一的另一种写法。
#1
2
If you can use an end-of-token symbol like $ or \b then you could do:
如果你可以使用象$或\b这样的令牌结尾符号，你可以:
MY?C(O|$)(M|$)(M|$)(A|$)(N|$)(D|$)
#2
1
What about MY?C(O(M(M(A(ND?)?)?)?)?)? ;-)
IMHO, this is the only other way to write it.
关于我的什么? C(O(M(M((ND)?)?)?)吗?)?这是唯一的另一种写法。