[luatex] [OT] The consumption of an input string.

[luigi scarso]

On Mon, Jun 17, 2013 at 4:54 PM, Paul Isambert <zappathustra at free.fr> wrote:

> luigi scarso <luigi.scarso at gmail.com> a écrit:
> > On Mon, Jun 17, 2013 at 2:43 PM, Paul Isambert <zappathustra at free.fr>
> wrote:
> >
> > > Hello all,
> > >
> > > This is not really a LuaTeX question, but I ask it here anyway since a
> > > lot of knowledgeable people read this list.
> > >
> > > I’ve been surprised to discover that
> > >
> > >     print(string.gsub('abc', '.*', '(%0)'))
> > >
> > > returns
> > >
> > >     (abc)()
> > >
> > > (similarly, “string.gmatch('abc', '.*')” returns two matches). I’d
> > > expect
> > >
> > >     (abc)
> > >
> > >
> >
> > myabe this can help
> >
> > > print(string.gsub("abc","%s*","(%0)"))
> > ()a()b()c()    4
> >
> > > print(string.gsub("abc","%S*","(%0)"))
> > (abc)()    2
> >
> > """
> > A pattern item can be
> >
> > a single character class followed by '*', which matches 0 or more
> > repetitions of characters in the class. These repetition items will
> always
> > match the longest possible sequence;
> > """
>
> Thank you Luigi, but “*” has the same definition in other languages,
> including those where there is no match on a final empty string.
>
> As for your first example, all languages behave the same as far as I
> can tell, as expected.
>
> Best,
> Paul
>
>
$ perl -e '$x="abc"; @w=($x=~ /(.*)/g);  print "tot. matches:", scalar(@w),
"  matches:($w[0])($w[1])\n"'
tot. matches:2  matches:(abc)()

$ perl -e '$x="abc"; @w=($x=~ /(.*)/);  print "tot. matches:", scalar(@w),
"  matches:($w[0])($w[1])\n"'
tot. matches:1  matches:(abc)()

in perl
"the modifier //g stands for global matching and allows the matching
operator to match within a string as many times as possible"
and I think it corresponds to
"These repetition items will always match the longest possible sequence;"
of pattern.

-- 
luigi
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://tug.org/pipermail/luatex/attachments/20130617/f1893b54/attachment.html>