#!/usr/bin/env perl
#
# See https://www.nntp.perl.org/group/perl.perl5.porters/2018/07/msg251463.html
# and https://www.nntp.perl.org/group/perl.perl5.porters/2018/07/msg251492.html.
use strict;
use warnings;
use Regexp::Parsertron;
# ------------------------------------------------
my($parser)     = Regexp::Parsertron -> new;
my(@test)       =
(
{
        item            => 1,
        expected        => '', # This is a placeholder since I don't know the answer.
        re                      => qr/(A(*COMMIT)|B)(A|B)D/,
},
{
        item            => 2,
        expected        => '', # This is a placeholder since I don't know the answer.
        re                      => qr/(A|B)(A(*COMMIT)|B)D/,
},
{
        item            => 3,
        expected        => '', # This is a placeholder since I don't know the answer.
        re                      => qr/(a(*COMMIT)b){0}a(?1)|aac/,
},
{
        item            => 4,
        expected        => '', # This is a placeholder since I don't know the answer.
        re                      => qr/(??{""})(a(*COMMIT)b){0}a(?1)|aac/,
},
);
my($expected);
my($got);
my($message);
my($result);
for my $test (@test)
{
        $result = $parser -> parse(re => $$test{re}, verbose => 1);
        if (! defined $result)
        {
                print "Parse is ambiguous. \n";
        }
        elsif ($result == 0) # 0 is success.
        {
                $got            = $parser -> as_string;
                $expected       = $$test{expected};
                $message        = "$$test{item}: re: $$test{re}. got: $got";
                $message        .= ' (After calling append(...) )' if ($$test{item} == 12);
                print "got: $got. expected: $expected. message: $message. \n";
        }
        else
        {
                print "Case $$test{item} failed to return 0 (== success) from parse(). \n";
        }
        # Reset for next test.
        $parser -> reset;
}