Solution to task 2

1 files changed, 110 insertions, 0 deletions

diff --git a/challenge-328/jo-37/perl/ch-2.pl b/challenge-328/jo-37/perl/ch-2.pl
new file mode 100755
index 0000000000..213d08af72
--- /dev/null
+++ b/challenge-328/jo-37/perl/ch-2.pl
@@ -0,0 +1,110 @@
+#!/usr/bin/perl
+
+use v5.26;
+use Test2::V0 -no_srand;
+use Test2::Tools::Subtest 'subtest_streamed';
+use Getopt::Long;
+use experimental 'signatures';
+
+use String::Compile::Tr;
+
+
+### Options and Arguments
+
+my ($tests, $examples, $remove_pairs, $make_good, $verbose);
+GetOptions(
+    'examples!' => \$examples,
+    'tests!'    => \$tests,
+    'verbose!'  => \$verbose,
+    '1!'        => \$remove_pairs,
+    '2!'        => \$make_good,
+) or usage();
+$remove_pairs = 1 unless $make_good;
+
+run_tests($examples, $tests);	# tests do not return
+
+usage() unless @ARGV == 1;
+
+sub usage {
+    die <<~EOS;
+    $0 - good string
+
+    usage: $0 [-examples] [-tests] [STR]
+
+    -examples
+        run the examples from the challenge
+     
+    -tests
+        run some tests
+
+    STR
+        a string
+
+    EOS
+}
+
+
+### Input and Output
+
+say "remove pairs: '@{[remove_pairs(@ARGV)]}'" if $remove_pairs;
+say "make good:    '@{[make_good(@ARGV)]}'" if $make_good;
+
+
+### Implementation
+#
+# For details see:
+# https://github.sommrey.de/the-bears-den/2025/07/04/ch-328.html#task-2
+
+
+sub remove_pairs ($str) {
+    1 while $str =~ s/(\p{Lu})(??{lc $1})|(\p{Ll})(??{uc $2})//;
+    $str;
+}
+
+sub make_good {
+    shift =~ s/(\p{LC})\1+/
+    trgen(2 * trgen(lc($1))->($&) < length($&) ? lc($1) : uc($1),
+        '', 'dr')->($&);
+    /iegr;
+}
+
+
+### Examples and Tests
+
+sub run_tests ($examples, $tests) {
+    return unless $examples || $tests;
+
+    state sub run_example ($str, $removed, $good, $name) {
+        subtest(qq{$name: "$str"} => sub {
+            plan 2;
+            my $result1 = remove_pairs($str);
+            is $result1, $removed,
+                qq{remove pairs -> "$removed"};
+            my $result2 = make_good($str);
+            is $result2, $good,
+                qq{make good -> "$good"};
+        });
+    }
+
+    plan 2;
+
+    $examples ? subtest_streamed(examples => sub {
+        my @examples = (
+            ['WeEeekly', 'Weekly', 'Weeekly', 'example 1'],
+            ['abBAdD', '', 'abAd', 'example 2'],
+            ['abc', 'abc', 'abc', 'example 3'],
+        );
+        plan scalar @examples;
+        for (@examples) {
+            run_example @$_;
+        }
+    }) : pass 'skip examples';
+
+    $tests ? subtest_streamed(tests => sub {
+        plan 2;
+        run_example('WeEeEkly', 'Wkly', 'Weekly', 'even repetitions');
+        run_example('WeEeEekly', 'Wekly', 'Weeekly', 'odd repetitions');
+    }) : pass 'skip tests';
+
+    exit;
+}