Re: Possible pattern bug

["Liam Devine" <liamdevine@...>]

On 16/11/13 21:22, Liam Devine wrote:
> On 16/11/13 20:59, Michael Savage wrote:
> > Hi lua-l,
> >
> > ( "[a] [b] c" ):match( "%[(.-)%] c" )
> > -> "a] [b"
> >
> > > From http://www.lua.org/manual/5.1/manual.html#5.4.1 or
> > http://www.lua.org/manual/5.2/manual.html#6.4.1:
> >
> > > a single character class followed by '-', which also matches 0 or more
> > > repetitions of characters in the class. Unlike '*', these repetition
> > > items will always match the shortest possible sequence;
> >
> > The shortest possible sequence for the above is "b". Is this a bug?
> >
> > Mike
>
> It is not, as it returns the first match [1]. If you wanted to capture
> the last sequence in square brackets you could prefix it with a greedy
> match:
> ( "[a] [b] c" ):match( ".*%[(.-)%] c" )
>
> [1] http://www.lua.org/manual/5.2/manual.html#pdf-string.match

I say could because it all depends on if you know your data format, the 
more you know the more specific you can be.
- Single lower case character
- Multiple lower case characters
- Numbers and lower case characters
- Upper and lower case characters
...

> print( ( "[a] [b] c" ):match( "(%l)%] c$" ) )
b
> print( ( "[a] [bddd] c" ):match( "(%l-)%] c$" ) )
bddd
> print( ( "[a] [b1d2c] c" ):match( "([%l%d]-)%] c$" ) )
b1d2c
> print( ( "[a] [KJhhgGGj] c" ):match( "(%a-)%] c$" ) )
KJhhgGGj

As you can see I also like to anchor the match when possible.

--
Liam