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Re: Regex result being defined when it shouldn't be(?)

by choroba (Cardinal)
on Nov 14, 2017 at 16:42 UTC ( [id://1203399]=note: print w/replies, xml ) Need Help??


in reply to Regex result being defined when it shouldn't be(?)

There are modules on CPAN that can help you building a parser. For example, you can use Marpa::R2 in the following way:
#!/usr/bin/perl use warnings; use strict; use Marpa::R2; my $dsl = << '__DSL__'; lexeme default = latm => 1 :default ::= action => ::first Config ::= Assignment Config action => merge | Assignment action => creat +e_config Assignment ::= Var (space equals space) Value (space) action => assig +n Value ::= number | String String ::= (quote) Quoteds (quote) Quoteds ::= Quoted Quoteds action => conca +t | Quoted Quoted ::= nonquote | quotedquote action => quote Var ::= Name || Array Array ::= atsign Name Index action => name_ +index Name ::= alpha alnum action => conca +t Index ::= (leftsquare) number (rightsquare) space ~ [\s]* alnum ~ [\w]+ alpha ~ [[:alpha:]] atsign ~ '@' equals ~ '=' leftsquare ~ '[' nonquote ~ [^'] number ~ [\d]+ quotedquote ~ '\'['] quote ~ ['] rightsquare ~ ']' __DSL__ sub concat { $_[1] . $_[2] } sub name_index { [ $_[2], $_[3] ] } sub quote { "'" } sub assign { [ ref $_[1] ? @{ $_[1] } : $_[1], $_[2] ] } sub merge { my %config = %{ $_[-1] }; (2 == @{ $_[1] } ? $config{ $_[1][0] } : $config{ $_[1][0] }[ $_[1 +][1] ]) //= $_[1][-1]; return \%config } sub create_config { my %config; $config{ $_[1][0] } = @{ $_[1] } == 2 ? $_[1][1] : do { my $ar = []; $ar->[ $_[1][1] ] = $_[1][2]; $ar }; \%config } my $grammar = 'Marpa::R2::Scanless::G'->new({source => \$dsl}); my $input = do { local $/; <DATA> }; my %config = %${ $grammar->parse(\$input, 'main') }; use Data::Dumper; print Dumper \%config __DATA__ @arr[2] = 3 str = 'xyz' @arr[2] = 5 str = 'abc\'d' @arr[1] = '#+#:'

Output:

$VAR1 = { 'str' => 'abc\'d', 'arr' => [ undef, '#+#:', '5' ] };
($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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