Hello,
On Sun, Aug 16, 2015 at 1:19 PM, <[email protected]> wrote:
> Hello,
> I would like to parse a text file containing the following data, with
> MARPA:
>
> EUR=089980
> GBP=063886
> AUD=135358
> ...
>
> When I run my program (see below), it only displays the first exchange
> rate, namely "089980", although my DSL file says that Catx (i.e., the
> exchange rate file) should contain one or more Expressions ("Expression+").
>
action => ::first in Catx ::= Expression+ action => ::first means that the
rule value will be limited to only the first element of the Expression+
sequence, so when I removed it, it showed all three rates.
> Furthermore, why can't you specify tokens with specific lengths in MARPA
> DSLs, e.g.,
>
> Label ~ \w{3}
>
> In the Catx data file's case, [currency] labels are always 3 characters
> long.
>
You can write Label ~ [\w] [\w] [\w] to achieve the same effect.
>
> Many thanks.
>
Hope this helps.
>
> Best regards,
>
> Philippe
>
>
>
> PERL script:
>
> -------------------
> #!/usr/bin/perl
> use strict;
> use warnings;
> use Marpa::R2;
> use Data::Dumper;
>
> my $data_file = '/Users/philippe/Desktop/MARPA/data.txt';
> my $dsl_file = '/Users/philippe/Desktop/MARPA/catx.dsl';
> my $input = slurp_file($data_file);
> my $dsl = slurp_file($dsl_file);
>
> my $grammar = Marpa::R2::Scanless::G->new( { source => \$dsl } );
> my $recce = Marpa::R2::Scanless::R->new(
> { grammar => $grammar, semantics_package => 'My_Actions' } );
> my $length_read = $recce->read ( \$input );
> die "Read ended after $length_read of ", length $input, " characters"
> if $length_read != length $input;
>
> if ( my $ambiguous_status = $recce->ambiguous() ) {
> chomp $ambiguous_status;
> die "Parse is ambiguous\n", $ambiguous_status;
> }
> my $value_ref = $recce->value;
> print "$$value_ref\n";
>
> sub slurp_file {
> my $file = shift;
> local $/ = undef;
> open my $fh, '<', $file or die "$!";
> my $data = <$fh>;
> close $fh;
> return $data;
> }
> sub My_Actions::do_extract_rate {
> my ( undef, $t1, undef, $t2 ) = @_;
> return $t2;
> }
> --------------------
>
> DSL file:
>
> -------------------
>
> :default ::= action => [name,values]
> lexeme default = latm => 1
>
> Catx ::= Expression+ action => ::first
> Expression ::= Label '=' Rate action => do_extract_rate
> Label ~ [\w]+
> Rate ~ [\d]+
> :discard ~ whitespace
> :discard ~ cr
> whitespace ~ [\s]+
> cr ~ [\n]+
>
>
>
> --------------------
>
>
>
>
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