On Sun, 15 Sep 2002, Steve Fink wrote:
: What should this do:
:
: my $x = "the letter x";
: print "yes" if $x =~ /the { $x .= "!" } .* !/;
Depends. I think it may be necessary for speed and safety reasons
to set COW on the string we're matching, so that you're always matching
against the original string. Perhaps we can make it work in the specific
case of concatenation, since we want to it to work for extensible
strings coming from a filehandle. But if a fast implementation needs to
keep pointers into a string rather than offsets from the beginning,
we're asking for core dumps if the string is modified out from under the
pointers, or we have to adjust all known pointers any time the string
may be modified.
: Does this print "yes"?
:
: print "yes" if "helo" =~ /hel { .pos-- } lo/;
Yes, that isn't modifying the string.
: Would it be correct for this to print 0? Would it be correct for this
: to print 2?
:
: my $n = 0;
: "aargh" =~ /a* { $n++ } aargh/;
: print $n;
:
: It might want to print zero because if regexes are not required to pay
: attention to modifications in the input string, then it can optimize
: away the a*.
Implementation dependent, but there will probably be a :modifier to
specifically turn off optimizations.
: What possible outputs are legal for this:
:
: "aaa" =~ /( a { print 1 } | a { print 2 })* { print "\n" } x/
Lots. :-)
Larry
