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Re: Iterating elements at different level

by choroba (Bishop)
on Jan 13, 2016 at 11:48 UTC ( #1152660=note: print w/replies, xml ) Need Help??


in reply to Iterating elements at different level

Discipulus teased me to try solving the problem using the Marpa parser. It took me a lot more time than I had thought: I didn't find a way how to retrieve the "depth" in a parse tree in order to multiply by it. You can attach 0 as the depth to each number, though, and increment it on each its inclusion into a list:
#!/usr/bin/perl use warnings; use strict; use feature qw{ say }; use Marpa::R2; use List::Util qw{ sum }; my $dsl = << '__DSL__'; lexeme default = latm => 1 :default ::= action => ::first Top ::= List action => resolve List ::= ('{') Terms ('}') Terms ::= Term+ separator => comma action => include Term ::= num action => create | List num ~ [0-9]+ comma ~ ',' __DSL__ sub create { [ [ $_[1], 0 ] ] } sub include { shift; [ map { map [$_->[0], 1 + $_->[1]], @$_ } @_ ] } + # do you still love me? sub resolve { shift; sum map $_->[0] * $_->[1], @{ $_[0] } } my $grammar = 'Marpa::R2::Scanless::G'->new({ source => \$dsl }); my @strings = ( '{{1,1},2,{1,1}}', # the functio +n should return 10 '{1,{4,{6}}}', # the functio +n should return 27 '{{1,1,1,1},{1,1,{2,2}},{1,{2,{3,3}}}}' # Buk 56 ); for my $s (@strings) { my $v = $grammar->parse(\$s, 'main'); say $$v; }
($q=q:Sq=~/;[c](.)(.)/;chr(-||-|5+lengthSq)`"S|oS2"`map{chr |+ord }map{substrSq`S_+|`|}3E|-|`7**2-3:)=~y+S|`+$1,++print+eval$q,q,a,

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