Yes and no. Technically I suppose you can, maybe doing something like this:
use 5.010;
use Data::Dumper;
$_ = "KEYWORD = VALUE MIN=2 MAX, = 12 WEIGHTED TOTAL= 20 WHAT =, 12 TEST =
1000";
our %results;
m!
(?&RECURSE)
(?(DEFINE)
(?<BAD_ASSIGNMENT> (?&BAD_LVSIDE)|(?&BAD_RVSIDE) )
(?<BAD_LVSIDE> (?&P_PLUS) = (?&P_STAR) )
(?<BAD_RVSIDE> (?&P_STAR) = (?&P_PLUS) )
(?<P_PLUS> \s*\p{P}+\s* )
(?<P_STAR> \s*\p{P}*\s* )
(?<SKIP_AND_RECURSE> (?&BAD_ASSIGNMENT) \w++ \s*+ (?&END) )
(?<END> (?&RECURSE) | \Z )
(?<KEYWORD_SEP> [\s\p{P}]*+ )
(?<RECURSE>
(?<keyword> \w++ ) #Grab a keyword
(?(?=(?&BAD_ASSIGNMENT)) #If it's followed by a malformed assignment,
(?&SKIP_AND_RECURSE) #Grab the right side and skip forward.
| #Otherwise,
(?: \s* = \s* (?<value> \w+ ) )? #If there's an assignment, grab the value.
(?{
$results{ $+{keyword} } = $+{value} // 1 #Get the results,
})
) (?&KEYWORD_SEP) #Eat up any whitespace/punctuation until the next keyword,
(?&END) #And recurse. If we are at the end of the string, we are done.
)
)
!x;
say Dumper \%results;
(Wow, gmail screwed up my indentation there. Here: http://ideone.com/vFSLc)
But really you shouldn't; There is no need to do it in a single expression,
other than causing your maintenance programmer some headache. And if doing
it in one go is a requirement for whatever reason, using Regexp::Grammars[1]
instead is probably a much better solution.
Brian.
[0]
http://search.cpan.org/~dconway/Regexp-Grammars-1.012/lib/Regexp/Grammars.pm
On Fri, Mar 18, 2011 at 7:24 PM, Chap Harrison <c...@pobox.com> wrote:
>
> This raises the question: is it possible, using a recursive regex and s///
> or m//, to - in one fell swoop - identify a correctly-formed string AND save
> the key=value pairs into a hash?
>
> Eons ago, when writing a SNOBOL4 program to match an arbitrary algebraic
> expression, I tried to make it evaluate the expression as it "unwound." I
> never succeeded -- so it's become something of a holy grail for me. Not a
> highly important one, though ;-)
>
>
>
> --
> To unsubscribe, e-mail: beginners-unsubscr...@perl.org
> For additional commands, e-mail: beginners-h...@perl.org
> http://learn.perl.org/
>
>
>
