in reply to Evaluate arbitrary boolean expressions
#!/usr/bin/perl use warnings; use strict; use feature qw{ say }; use Marpa::R2; my $dsl = << '__DSL__'; :default ::= action => ::first lexeme default = latm => 1 Exp ::= Term | Exp (disj) Term action => disj Term ::= Factor | Term (conj) Factor action => conj Factor ::= Atom | Negation | Bracketed Bracketed ::= (lbra) Exp (rbra) Negation ::= (excl) Factor action => neg Atom ::= true action => true | false action => false true ~ 'T' false ~ 'F' excl ~ '!' conj ~ '&&' disj ~ '||' lbra ~ '(' rbra ~ ')' ws ~ [\s]+ :discard ~ ws __DSL__ sub true { 1 } sub false { 0 } sub neg { ! $_[1] } sub conj { $_[1] && $_[2] } sub disj { $_[1] || $_[2] } my $grammar = 'Marpa::R2::Scanless::G'->new({source => \$dsl}); my $input = '((T) || (!(T))) && !(F && F && F && F && ! (T))'; my $value = ${ $grammar->parse(\$input, 'main') }; say $value ? 'TRUE' : 'FALSE';
($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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