Solution to task 2

1 files changed, 68 insertions, 0 deletions

diff --git a/challenge-166/jo-37/perl/ch-2.pl b/challenge-166/jo-37/perl/ch-2.pl
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+++ b/challenge-166/jo-37/perl/ch-2.pl
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+#!/usr/bin/perl
+
+use v5.16;
+use warnings;
+use autodie;
+use List::Util qw(max pairgrep);
+use experimental 'signatures';
+
+
+die <<EOS unless @ARGV;
+usage: $0 dir...
+
+dir...
+    Compare content of given directories
+
+EOS
+
+
+### Input and Output
+
+print_diff(\@ARGV, dir_diff(@ARGV));
+
+
+### Implementation
+
+# Build a hash with the file names found in any directory as keys and an
+# array indicating the files' presence within the directories.  Files
+# contained in all directories are filtered out.  Equally named files
+# and directories are regarded as different objects.  File contents are
+# not compared.
+sub dir_diff (@dirs) {
+    my %files;
+    # Loop over the directories.
+    while (my ($i, $dir) = each @dirs) {
+        opendir(my $dh, $dir);
+        # Loop over the directory's files.
+        while (readdir $dh) {
+            # Append "/" to directories.
+            $_ .= '/' if -d "$dir/$_";
+            # Set an indicator for the current directory.
+            $files{$_}[$i] = 1;
+        }
+        closedir $dh;
+    }
+
+    # Exclude files that exist in all directories.
+    +{pairgrep {@dirs > grep $_, @$b} %files};
+}
+
+# Print the directory diff in a terse matrix format: "X" indicates the
+# presence of a file in a directory.
+sub print_diff ($dir, $diff) {
+    my $dlen = max map length, @$dir;
+    my $flen = max 0, map length, keys %$diff;
+
+    # Table header
+    printf "%${flen}s" . (" | %${dlen}s" x @$dir) . "\n",
+        '', @$dir;
+    printf "%${flen}s" . ("-+-%${dlen}s" x @$dir) . "\n",
+        '-' x $flen, ('-' x $dlen) x @$dir;
+
+    # Table rows
+    for my $file (sort keys %$diff) {
+        printf "%-${flen}s", $file;
+        printf " | %${dlen}s", 'X' x !!$diff->{$file}[$_] for 0 .. $#$dir;
+        print "\n";
+    }
+}