kicad-developers team mailing list archive

[Tiger12506 <tiger12506@xxxxxxxxx>]

No, '?' also means zero-or-one in RegEx syntax, it's just that it *also* 
happens to mean "make the previous quantity modifier non-greedy" if 
there is a previous quantity modifier. Notice the double-question mark 
regex in the documentation quote previously pasted. That one means make 
the zero-or-one quantifier non-greedy.

On 5/5/2018 5:58 PM, Jeff Young wrote:
> Ahhh… I’m mixing up XPath and RegEx syntax.  ‘?’ is zero-or-one in 
> XPath, not RegEx.
>
> Thanks Shiv & Thomas.
>
> Cheers,
> Jeff
>
>
> > On 5 May 2018, at 15:37, Shivpratap Chauhan <shivmsit@xxxxxxxxx 
> > <mailto:shivmsit@xxxxxxxxx>> wrote:
> >
> > According to documentation at 
> > http://docs.wxwidgets.org/3.0/overview_resyntax.html
> >
> > |*? +? ?? {m}? {m,}? {m,n}?| 	/Non-greedy/ quantifiers, which match 
> > the same possibilities, but prefer the smallest number rather than 
> > the largest number of matches (see Matching 
> > <http://docs.wxwidgets.org/3.0/overview_resyntax.html#overview_resyntax_matching>). 
> >
> >
> >
> > There seems to be difference greedy vs non-greedy quantifiers!
> >
> >
> > Thanks,
> > Shiv
> >
> >
> >
> > On Sat, May 5, 2018 at 6:49 PM, Jeff Young <jeff@xxxxxxxxx 
> > <mailto:jeff@xxxxxxxxx>> wrote:
> >
> >     We have a couple of regular expressions of the form:
> >
> >     wxRegEx re( ".*?\\$\\{(.+?)\\}.*?", wxRE_ADVANCED );
> >
> >
> >     Now perhaps I’m too old to remember this stuff correctly, but .*?
> >     is redundant, isn’t it?
> >
> >     And shouldn’t .+? just be .*?  (And for that matter, shouldn’t it
> >     really be [^}]*?)
> >
> >     Thanks,
> >     Jeff.
> >
> >
> >     Note that I’m looking at this because it needs to check for both
> >     ${…} and $(…) formatted envvars, which I think boils down to:
> >
> >     .*(\\$\\{([^}]*)\\})|(\\$\\(([^)]*)\\)).*
> >
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