Solution to task 2

1 files changed, 71 insertions, 0 deletions

diff --git a/challenge-110/jo-37/perl/ch-2.pl b/challenge-110/jo-37/perl/ch-2.pl
new file mode 100755
index 0000000000..a833da13f1
--- /dev/null
+++ b/challenge-110/jo-37/perl/ch-2.pl
@@ -0,0 +1,71 @@
+#!/usr/bin/perl -s
+
+use v5.16;
+use Test2::V0;
+use experimental qw(signatures postderef);
+
+our $examples;
+
+run_tests() if $examples;	# does not return
+
+die <<EOS unless @ARGV;
+usage: $0 [-examples] [file ...]
+
+-examples
+    run the examples from the challenge
+ 
+file ...
+    file(s) to be transposed.  Multiple files are concatenated first,
+    then transposed.
+
+EOS
+
+
+### Input and Output
+
+{
+    local $, = ',';
+    # perlvar states:
+    #   passing "\*ARGV" as a parameter to a function that expects a
+    #   filehandle may not cause your function to automatically read the
+    #   contents of all the files in @ARGV.
+    # It seems to work, though.
+    say @$_ for transpose_file(\*ARGV);
+}
+
+
+### Implementation
+
+# Read lines from the given filehandle, split them at commas (chopping
+# newlines) and push the parts onto a list of arrays.
+sub transpose_file ($fh) {
+    my @tr;
+    while (<$fh>) {
+        my @part = split /,|\n/;
+        while (my ($i, $v) = each @part) {
+            push $tr[$i]->@*, $v;
+        }
+    }
+
+    @tr;
+}
+
+
+### Examples and tests
+
+sub run_tests {
+    open my $fh, '<', \(<<EOS =~ s/^ +//gmr);
+        name,age,sex
+        Mohammad,45,m
+        Joe,20,m
+        Julie,35,f
+        Cristina,10,f
+EOS
+    is [transpose_file($fh)], [
+        [qw(name Mohammad Joe Julie Cristina)],
+        [qw(age 45 20 35 10)],
+        [qw(sex m m f f)]], 'example';
+
+    done_testing;
+    exit;
+}