Re: Modifier ? in lua pattern matching

[Ico Doornekamp <lua@...>]

* On 2008-05-26 Bertrand Mansion <golgote@mamasam.com> wrote  :

> Hi,
>
> About pattern matching, the PiL book says:
>
> "Unlike some other systems, in Lua a modifier can only be applied to a  
> character class; there is no way to group patterns under a modifier. For 
> instance, there is no pattern that matches an optional word (unless the 
> word has only one letter). Usually you can circumvent this limitation 
> using some of the advanced techniques that we will see later."
>
> My problem is that I didn't find any examples for that "later" and I  
> didn't manage to figure out how to do it myself.
> Basically, I have a string that can take these three forms for example:
>
> DATETIME
> VARCHAR(10)
> FLOAT(10,2)
>
> With perl regex, I could use the ? modifier to have an all in one pattern 
> like this for example:
> '^([A-Z]+)(\(([0-9]+)(,([0-9]+))?\))?$'
>
> With Lua, do I have to write three different patterns or is there a  
> better solution?

Would this be of any help ?

as = {
   "DATETIME",
   "VARCHAR(10)",
   "FLOAT(10,2)",
}

for _, a in ipairs(as) do
   word, arg1, arg2 = a:match("(%w+)%(?(%d*),?(%d*)%)?")
   print(word, arg1, arg2)
end


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:wq
^X^Cy^K^X^C^C^C^C