How do I split a string on highly structured/nested data?

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

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Re: How do I split a string on highly structured/nested data? by lhoward (Vicar) on Jun 07, 2000 at 03:50 UTC
One approach is to use a parser like Parse::RecDescent. A real parser (as opposed to parsing a string with a regular expression alone) is much more powerful and can be more apropriate for parsing highly structured/nested data like your example. `use Parse::RecDescent; my $teststr="a,b,op2(c,d),op3(e,op4(f,g))"; my $grammar = q { content: /[^\)\(\,]+/ function: content '(' list ')' value: content item: function \| value list: item ',' list \| item startrule: list }; my $parser = new Parse::RecDescent ($grammar) or die "Bad grammar!\n"; defined $parser->startrule($teststr) or print "Bad text!\n";` [download] For other approaches see the discussion on Balancing Parens.	[reply] [d/l]
Re: How do I split a string on highly structured/nested data? by Anonymous Monk on Aug 17, 2000 at 03:10 UTC
This should work more reliably in case there are repeated strings: `$_ = "a,b,op2(c,d),(e),(f),(f,g),op3(e,op4(f,g))\n"; print; ($re=$_)=~s/(($)\|($)\|.)/$2\Q$1\E$3/gs; @$ = (eval{/$re/}); die $@ if $@=~/unmatched/; $re = join'\|',map{quotemeta}@$; print join"\n",/((?:$re\|[^,])+)/g;` [download]	[reply] [d/l]
Re: How do I split a string on highly structured/nested data? by merlyn (Sage) on Aug 17, 2000 at 10:09 UTC
lhoward's grammar seems unnecessarily complicated. Let's simplify it a bit, as well as grabbing what is needed for the answer (the split items): `use Parse::RecDescent; my $teststr="a,b,op2(c,d),op3(e,op4(f,g))"; my $grammar = q { startrule: list list: <leftop: item ',' item> item: word '(' list ')' <commit> { "$item[1](".join(",",@{$item[3]})." +)" } \| word word: /\w+/ }; my $parser = new Parse::RecDescent ($grammar) or die "Bad grammar!\n"; + defined (my $result = $parser->startrule($teststr)) or print "Bad text +!\n"; print map "<<< $_ >>>\n", @$result;` [download] Yes, there it is. `$result` is an array ref of the split-apart items.	[reply] [d/l]
Re: How do I split a string on highly structured/nested data? by Anonymous Monk on Aug 17, 2000 at 10:02 UTC
(I didn't mean more reliably than lhoward's answer, I meant more reliably than my previous answer, which seems to have been appropriately edited away) Originally posted as a Categorized Answer.	[reply]
Re: How do I split a string on highly structured/nested data? by Anonymous Monk on Aug 17, 2000 at 02:46 UTC
Re: How do I split a string on highly structured/nested data? Originally posted as a Categorized Answer.	[reply]